GTA
Airguns by Make and Model => Crosman Airguns => Topic started by: Spooner on March 27, 2021, 08:15:21 PM
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as many of you know, i have a 1322 modified carbine with 14.5" LW barrel, Mellon flat top piston/valve and max flow transfer port. i did a few chrony shots today at a tin can just to see what all of this got me. i am shooting Crosman 14.3 grain super points. so, at five pumps i got an average of about 405 FPS. it seems to be pretty consistent around that range at 5 pumps.
at 10 pumps, i got 478, 450, 481. except for the middle reading, the other two were consistent. i only did the three shots as the neighbors were coming out and about enjoying the nice day. this seems a little low to me for what is in this gun, but since this .22 cal is my first... i really have nothing to compare it to. i know that Crosman says "up to 500 FPS" for the 1322 in stock form, but i guess i expected a little better for the mods i put in. there is no air retention, so i know i have the PA adjusted correctly.
i dont know? what are you folks with similar set ups getting? just curious if what i am seeing is a normal range for this heavier pellet.
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Crsoman says "Up to 460 FPS" for the 1322 pistol (pellet weight not specified).
The 14.3 grain pellet is not heavy - pretty much the standard lead pellet weight for .22 caliber air guns.
Check for correct head space adjustment of the FTP.
Altitude makes a difference for MSP.s and springers, but Ohio is probably mostly not very high.
My 1322 with FTP, 18" barrel, and increased valve volume runs are 484 fps for ten pump and 533 for 15 pumps. However I have the disadvantage of being at 5835 foot elevation. I expect those numbers might be 500 fps and 565 at low elevation.
I do not think the larger valve volume is an advantage at low pump counts. In retrospect, I would not have done that.
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Crsoman says "Up to 460 FPS" for the 1322 pistol (pellet weight not specified).
The 14.3 grain pellet is not heavy - pretty much the standard lead pellet weight for .22 caliber air guns.
Check for correct head space adjustment of the FTP.
Altitude makes a difference for MSP.s and springers, but Ohio is probably mostly not very high.
My 1322 with FTP, 18" barrel, and increased valve volume runs are 484 fps for ten pump and 533 for 15 pumps. However I have the disadvantage of being at 5835 foot elevation. I expect those numbers might be 500 fps and 565 at low elevation.
I do not think the larger valve volume is an advantage at low pump counts. In retrospect, I would not have done that.
Thanks Craig,
I have the FTP adjusted based on help from folks here and i am fairly confident it is correct? it locks over at about 1/2" from closed and i made sure that it was in full contact with the piston when setting it up before i put the o-ring back on the piston and finished it up. we are at about 1200 ft in altitude and with the shorter barrel than yours... it sounds like what i am getting is probably consistent with yours at higher elevation. i did a tissue test as well, just to make sure there were no leaks there and there wasnt. maybe i am just expecting too much from this one?
My 1377 is about the same... at 10 pumps, 589-592 FPS consistently at 10 pumps with the exact same valve/TP setup. at 6 pumps... 500-506 FPS. these were with Crosman 7.4 grain super points. i had hoped for a little better at 10 pumps with this one too, but its still pretty decent. 6 pumps is where i stay at this one anyway.
i have my FX pocket Chrono set up for the correct gun/pellet information, but its the actual range setting i am not completely certain about? right now, it is set up for the "Airgun Pistol 295-720 FPS" setting at 20% return and 0.0% calibration. these seem correct for the gun but i may try the 10% return and see what i get.
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Just wondered if you deburred the tube slots and holes before installing the valve. Sometimes the outer O ring gets nicked as it slides past the sharp edges and causes a loss of compression on each pump resulting in less air in the valve. I don't have a carbine barrel on my 1322 but with Mellon set up and a 12" barrel it gets 495fps on 8 pumps and 525fps on 10 pumps with 14.3g pellets. I have had a number of 1322s over the years that responded differently to mods but your numbers do seem lower than they should be. I got around 600fps on one with a rifle barrel, ice maker tube transfer port & Mountain Air Flat Top set up at 12 pumps a while back. I wonder is the LW barrel choked? Would that make a difference as I only have Crosmans?
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Just wondered if you deburred the tube slots and holes before installing the valve. Sometimes the outer O ring gets nicked as it slides past the sharp edges and causes a loss of compression on each pump resulting in less air in the valve. I don't have a carbine barrel on my 1322 but with Mellon set up and a 12" barrel it gets 495fps on 8 pumps and 525fps on 10 pumps with 14.3g pellets. I have had a number of 1322s over the years that responded differently to mods but your numbers do seem lower than they should be. I got around 600fps on one with a rifle barrel, ice maker tube transfer port & Mountain Air Flat Top set up at 12 pumps a while back. I wonder is the LW barrel choked? Would that make a difference as I only have Crosmans?
i checked the tube for bur but didnt feel any so didnt debur them before assembly. i probably should have anyway as i have a diamond file perfect for that :-\. the LW barrels are choked and i never gave that any thought. i am sure that being choked has an impact, but these numbers i am getting just seem low for what the FTP mods are supposed to do? it is interesting though... i took a single chrony reading from my non modified 1377 which also has the 14.5" LW barrel but all stock internals. at 10 pumps using destroyer 7.4gr Crosman pellets... 588 FPS which is the same as my 1377 with the Mellon FTP set up and max flow TP? somewhere, i have not done something right in both of these guns? i dread the thought of having to take them apart but i may have too just to inspect the components. my 1377 modified shoots well enough to to be ok for my needs until i have time to look inside, so i may tear in to the 1322 after giving some thought as to what i could have possibly done wrong... i just do not know what that possibly could have been? these mods are very straight forward to do. if its just damaged o-rings from sharp tube edges... thats easy enough to correct.
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Try JSB pellets, as they are much softer and of more consistent quality compared to Crosman pellets.
They should zip out faster from your choked barrel.
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Try JSB pellets, as they are much softer and of more consistent quality compared to Crosman pellets.
They should zip out faster from your choked barrel.
i have several tins of .177 JSB now, most are heavies in preparation for sighting in my new 2400KT and to test in my repaired 1077... but i have one tin of 8.4g JSB Stratton pointed pellets in .177 that i am very eager to try out. i really like the looks of all of these JSB pellets... very uniform and cleanly made. ;)
i also wanna add... WOW do these LDC's make a difference! when i fired my non modded 1377 it sounded like a 22 rim fire going off, but that modded 1377... a quiet little poof! very nice!!! 8)
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Hi,
my 1322 with 18 inch barrel:
10 pump 520fps
17 pump 581fps
20 pump 602 fps
23 pump 614fps
with jsb 14.3
greetings Andi
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As additional data, at my altitude, with 20 pumps -561 fps, and with 25 pumps - 599 fps.
Some air retained with 20 and 25 pumps. More spring!
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Hi,
my 1322 with 18 inch barrel:
10 pump 520fps
17 pump 581fps
20 pump 602 fps
23 pump 614fps
with jsb 14.3
greetings Andi
Thanks Andi... does yours have the flat top setup or the stock one? i tried a couple shots at 15 pumps and got 558 and 561. i couldnt rely on the two i did at 20 pumps. i had air retention even with the PA adjusted all the way in. not sure what is up with that either as this PA is designed for this purpose.
i watched a video of a guy last night who did 50 pumps! his setup was very similar to mine except he had a stronger spring rather than a PA. can you imagine... 50 pumps and he did it several times using different pellets. one thing is for sure... he put most of them through a half inch piece of plywood at 20 yards getting 790FPS... yikes!!!
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As additional data, at my altitude, with 20 pumps -561 fps, and with 25 pumps - 599 fps.
Some air retained with 20 and 25 pumps. More spring!
same here... air retention at 20 pumps with the PA adjusted all the way in.
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i have the gmac valve,
large transfer port and a hollow probe as setup. the spring on the hammer is original.
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Might be further ahead going for the multi shot pumper mods ???
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My experience is the choked LW barrel will reduce the velocity by about 20 FPS.
So you're not that far off as you might think.
The best method to make power with a short barrel and 10-15 pumps is lower the valve volume.
This will increase the pressure in the valve and release it quickly.
Experimented with a 13xx gun with various barrels/calibers here:
https://www.gatewaytoairguns.org/GTA/index.php?topic=164421.0 (https://www.gatewaytoairguns.org/GTA/index.php?topic=164421.0)
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My experience is the choked LW barrel will reduce the velocity by about 20 FPS.
So you're not that far off as you might think.
The best method to make power with a short barrel and 10-15 pumps is lower the valve volume.
This will increase the pressure in the valve and release it quickly.
Experimented with a 13xx gun with various barrels/calibers here:
https://www.gatewaytoairguns.org/GTA/index.php?topic=164421.0 (https://www.gatewaytoairguns.org/GTA/index.php?topic=164421.0)
wow Ron... your skills with these mods and your resources to carry them out are just scary, lol 8)! i read that whole thread and im pretty sure it was fear i was experiencing as i read each post, hahaha! way out of my ability to do. knowing that the choked barrels have an effect on FPS helps and i never really expected the 1322 to be more than marginally better over OEM. the 1377 however, i did have better expectations and it seems to be about the same as OEM? my goal was to improve the FPS at 10 pumps over OEM and stop there. why the PA doesnt do a full dump at full in adjustment at 20 pumps is a question mark, but i wont go to 20 pumps again. it works good up to 17 pumps so my goal to stick to 10 pumps works there. i will probably have to find a much stronger spring for the PA if i ever need to go further?
the Mellon Valve set definitely gives me easier pumping, so i achieved that advantage, but seem to have failed getting better FPS at 10 pumps and it has to be something i did wrong in the setup? still, 500 to 513 FPS at 6 pumps is pretty decent... it just doesnt seem to gain much going up to 10 pumps at 589 FPS. maybe that is normal, i just dont know? these are my first mod attempts, so nothing really to compare them to. they both shoot very well, and both are extremely accurate, so it isnt like they are defective in any way... just less than i had hoped for.
i still have my unmodified 1377 CCS gun with the non stamped tube. i am going to do the Mellon valve/piston and TP mod to it for comparison but this time i am going to take more time, clean up the edges of the tube, and do this much more carefully. i decided to start over on a different gun rather than just tear in to the two i have. this will give me a second gun to compare with and hopefully help me figure out what (if anything) i did wrong on the other two?
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The weak link on the 13xx pumpers is the pump arm link.
It's about .050" stamped mild steel (beer cans?) and the secondary link can crack or bend if pushed hard.
In my experiments I modified a 70s era NOS 766 pump link.
It's about .060" with a straight secondary link.
I use them on all my modified pumpers.
Here's another experiment using a 3/4" tube and 3 1/2" stroke.
Uses both a cup seal and o-ring seal piston for comparison.
It's equivalent to a 5" stroke 2100.
https://www.gatewaytoairguns.org/GTA/index.php?topic=177024.msg156004326#msg156004326 (https://www.gatewaytoairguns.org/GTA/index.php?topic=177024.msg156004326#msg156004326)
A lighter valve spring and an MRod valve stem will release higher pressure.
The stock valve stem is soft and will take a set and require more force to open the valve.
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The weak link on the 13xx pumpers is the pump arm link.
It's about .050" stamped mild steel (beer cans?) and the secondary link can crack or bend if pushed hard.
In my experiments I modified a 70s era NOS 766 pump link.
It's about .060" with a straight secondary link.
I use them on all my modified pumpers.
Here's another experiment using a 3/4" tube and 3 1/2" stroke.
Uses both a cup seal and o-ring seal piston for comparison.
It's equivalent to a 5" stroke 2100.
https://www.gatewaytoairguns.org/GTA/index.php?topic=177024.msg156004326#msg156004326 (https://www.gatewaytoairguns.org/GTA/index.php?topic=177024.msg156004326#msg156004326)
A lighter valve spring and an MRod valve stem will release higher pressure.
The stock valve stem is soft and will take a set and require more force to open the valve.
those are very impressive numbers :o! Adding the gauges to your builds is awesome as well 8).
i will check the pump links... easy enough to look at. ;)
update: just checked both guns... pump arms are ok. I also did a duration test on both. pumped them up to six pumps, let them sit for several hours then ran them with the chrony. results were the same as pump and fire. so, at least i know that there are no leaks from the valve back through the TP.
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so, let me ask the question i should have asked at the start, and i want to focus on the 1377 since that is the one i care most about. forgetting the max flow TP and other incidental mods...
a stock 1377, with Mellon FT valve and piston with a LW 14.6" barrel using 7.4g pointed pellets or similar. "Realistically" what "should" i be seeing on average for FPS at 10 pumps? knowing this will help me the most.
thanks ;D
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i was going over the two guns today, just checking what i could with them assembled. the pump linkage on the 1322 has a lot of side to side play where it attaches to the Mellon piston and it looks like the pivot pin in the piston has a little slop as well. the 1377 has a little, not as much as the 1322, but some. this new 1377 build is going to be an experiment in shimming in critical places. this slop in the linkage could easily wear out the pivot pin area of the piston. i dont know if this could affect pumping efficiency as it seems to still go the full travel, but slop is never good either way. ;)
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The Mellon web site sells a solid pin kit with bushings that take up the slop that the 13XX guns have. I just used his bushings with a solid pin and C clips I made myself on a 392 and 1322. I never liked the split roll pins. They are too hard on the gun driving them in & out if you have to remove them to adjust things or reseal.
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The Mellon web site sells a solid pin kit with bushings that take up the slop that the 13XX guns have. I just used his bushings with a solid pin and C clips I made myself on a 392 and 1322. I never liked the split roll pins. They are too hard on the gun driving them in & out if you have to remove them to adjust things or reseal.
I have one of those but couldn't clearly figure out how the spacers went in. I went with Alchemy solid pins instead. The slop I have to fix is where the linkage connects to the piston itself. On my 1322, it is really a lot. I can find washers at work to deal with it once I get going on this new build then apply that to the other two.
Thanks ;D
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I see what you mean about the piston itself allowing side to side movement of the link arm. I have Mellon pistons and Mountain Air ones and they both have that wider slot where the link pin goes through. I wonder if that was on purpose for some reason for as they both have the same wide slot. If you try the washers there let us know if it helps. The front pivot wafer like bushing from Mellon works great. You spread the forks at the pivot hole and slip it in between them to give you more solid surface contact for the pin to go through and take up the slop at the front end.
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I see what you mean about the piston itself allowing side to side movement of the link arm. I have Mellon pistons and Mountain Air ones and they both have that wider slot where the link pin goes through. I wonder if that was on purpose for some reason for as they both have the same wide slot. If you try the washers there let us know if it helps. The front pivot wafer like bushing from Mellon works great. You spread the forks at the pivot hole and slip it in between them to give you more solid surface contact for the pin to go through and take up the slop at the front end.
it was probably intentional since this valve set can be used with the "760 as well as others" and the tolerances are most likely wider than the 13xx... that would be my guess.
i tried spreading apart the front of the linkage and see now how that spacer goes in... thanks for that ;). i was afraid to try it originally but figured that was where it somehow went. i will use that on this new build with the Alchemy pin. i will probably have to grind down some wider washers at work in order to get a large enough ID for the pin... will let you know how that works out. ;)
it will probably be a couple weeks before parts come in for this build but i can use the OEM piston to get some rough measurements for spacers. 8)
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I see what you mean about the piston itself allowing side to side movement of the link arm. I have Mellon pistons and Mountain Air ones and they both have that wider slot where the link pin goes through. I wonder if that was on purpose for some reason for as they both have the same wide slot. If you try the washers there let us know if it helps. The front pivot wafer like bushing from Mellon works great. You spread the forks at the pivot hole and slip it in between them to give you more solid surface contact for the pin to go through and take up the slop at the front end.
it was probably intentional since this valve set can be used with the "760 as well as others" and the tolerances are most likely wider than the 13xx... that would be my guess.
i tried spreading apart the front of the linkage and see now how that spacer goes in... thanks for that ;). i was afraid to try it originally but figured that was where it somehow went. i will use that on this new build with the Alchemy pin. i will probably have to grind down some wider washers at work in order to get a large enough ID for the pin... will let you know how that works out. ;)
it will probably be a couple weeks before parts come in for this build but i can use the OEM piston to get some rough measurements for spacers. 8)
Ace Hardware sells countless washers like stainless, brass, copper, and zinc-plated.
My 13xx sports 2 to get rid of the side to side slop.
You can lap them with sandpaper placed on a solid and even surface if they are too thick.
I also installed ultra thin shims on the piston—-don’t recall where I got them from, but they must have been for the 10/22 kit I bought a long time ago.
Magnum Air Power used to sell oversize pins for the 13xx piston, and I happen to have bought 2 of them.
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thanks Rick ;)
no mainstream hardware stores near here, just a couple decent mom and pop hardware stores. i am going to check them out today, but i have access to countless types and sizes at work. ill find something i can make work in one place or the other. ;)
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Got lucky at the local hardware store. Picked out two diameters of steel washers that fit inside the oem piston and have a perfect inner diameters. Also found some thicker bronze ones. Won't know which ones until my Mellon FTP set comes in, but am sure one of the three will work. 8)
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Spooner sir, Steve Corcoran has lowered the prices on his grips and grip set:
https://www.scstocksandgrips.com/grips-for-sale (https://www.scstocksandgrips.com/grips-for-sale)
For me, it's Steve Corcoran or Vernon Austin.
I ordered a PROD set from him for my new build.
Once you get a set from either the 2 gents it's hard to settle for less ;D
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Spooner sir, Steve Corcoran has lowered the prices on his grips and grip set:
https://www.scstocksandgrips.com/grips-for-sale (https://www.scstocksandgrips.com/grips-for-sale)
For me, it's Steve Corcoran or Vernon Austin.
I ordered a PROD set from him for my new build.
Once you get a set from either the 2 gents it's hard to settle for less ;D
The detail on his Sporter Buttstock is incredible! That is a beautiful work of art! ;D
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as many of you know, i have a 1322 modified carbine with 14.5" LW barrel, Mellon flat top piston/valve and max flow transfer port. i did a few chrony shots today at a tin can just to see what all of this got me. i am shooting Crosman 14.3 grain super points. so, at five pumps i got an average of about 405 FPS. it seems to be pretty consistent around that range at 5 pumps.
at 10 pumps, i got 478, 450, 481. except for the middle reading, the other two were consistent. i only did the three shots as the neighbors were coming out and about enjoying the nice day. this seems a little low to me for what is in this gun, but since this .22 cal is my first... i really have nothing to compare it to. i know that Crosman says "up to 500 FPS" for the 1322 in stock form, but i guess i expected a little better for the mods i put in. there is no air retention, so i know i have the PA adjusted correctly.
i dont know? what are you folks with similar set ups getting? just curious if what i am seeing is a normal range for this heavier pellet.
What kind of sear do you have on this build?
I am experiencing a bit of hammer drag on my Steve Super Sear.
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as many of you know, i have a 1322 modified carbine with 14.5" LW barrel, Mellon flat top piston/valve and max flow transfer port. i did a few chrony shots today at a tin can just to see what all of this got me. i am shooting Crosman 14.3 grain super points. so, at five pumps i got an average of about 405 FPS. it seems to be pretty consistent around that range at 5 pumps.
at 10 pumps, i got 478, 450, 481. except for the middle reading, the other two were consistent. i only did the three shots as the neighbors were coming out and about enjoying the nice day. this seems a little low to me for what is in this gun, but since this .22 cal is my first... i really have nothing to compare it to. i know that Crosman says "up to 500 FPS" for the 1322 in stock form, but i guess i expected a little better for the mods i put in. there is no air retention, so i know i have the PA adjusted correctly.
i dont know? what are you folks with similar set ups getting? just curious if what i am seeing is a normal range for this heavier pellet.
What kind of sear do you have on this build?
I am experiencing a bit of hammer drag on my Steve Super Sear.
I have the "correct width" stainless steel sear from Alchemy Airwerks in all three builds. ;)
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FWIW
Picked up a few 13xx guns recently off eBay.
Resealed them and the 1322 made 450 FPS with 10 pumps.
Made an adjustable piston and replaced the stock breech and 10" barrel with an 18" barrel.
05 pumps 414 FPS 05.44 FPE
07 pumps 482 FPS 07.38 FPE
10 pumps 555 FPS 09.78 FPE
12 Pumps 590 FPS 11.05 FPE
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FWIW
Picked up a few 13xx guns recently off eBay.
Resealed them and the 1322 made 450 FPS with 10 pumps.
Made an adjustable piston and replaced the stock breech and 10" barrel with an 18" barrel.
05 pumps 414 FPS 05.44 FPE
07 pumps 482 FPS 07.38 FPE
10 pumps 555 FPS 09.78 FPE
12 Pumps 590 FPS 11.05 FPE
Thanks Ron ;). If you can get those kinds of numbers with just a reseal and and an 18" barrel... my 1322 with the flat top is under performing by quite a bit.
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Spooner sir, Steve Corcoran has lowered the prices on his grips and grip set:
https://www.scstocksandgrips.com/grips-for-sale (https://www.scstocksandgrips.com/grips-for-sale)
For me, it's Steve Corcoran or Vernon Austin.
I ordered a PROD set from him for my new build.
Once you get a set from either the 2 gents it's hard to settle for less ;D
Absolutely beautiful work, thanks for posting the link. I'm just starting out but I'm sure I'll start making a few purchases soon enough.
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Spooner sir, Steve Corcoran has lowered the prices on his grips and grip set:
https://www.scstocksandgrips.com/grips-for-sale (https://www.scstocksandgrips.com/grips-for-sale)
For me, it's Steve Corcoran or Vernon Austin.
I ordered a PROD set from him for my new build.
Once you get a set from either the 2 gents it's hard to settle for less ;D
Absolutely beautiful work, thanks for posting the link. I'm just starting out but I'm sure I'll start making a few purchases soon enough.
https://www.gatewaytoairguns.org/GTA/index.php?topic=148550.new#new (https://www.gatewaytoairguns.org/GTA/index.php?topic=148550.new#new)
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FWIW
Picked up a few 13xx guns recently off eBay.
Resealed them and the 1322 made 450 FPS with 10 pumps.
Made an adjustable piston and replaced the stock breech and 10" barrel with an 18" barrel.
05 pumps 414 FPS 05.44 FPE
07 pumps 482 FPS 07.38 FPE
10 pumps 555 FPS 09.78 FPE
12 Pumps 590 FPS 11.05 FPE
Thanks Ron ;). If you can get those kinds of numbers with just a reseal and and an 18" barrel... my 1322 with the flat top is under performing by quite a bit.
The 18" barrel was counterbored and the port opened to .155", also used ice maker line for the TP.
Curiosity got the best of me so this morning in the name of science, swapped in an unmodified 14 1/2" LW barrel, then a counterbored 14 1/2" Crosman barrel with .155" port.
Referenced to the 18" Crosman barrel.
14 1/2" unmodified LW barrel
05 pumps 376 FPS -38 FPS
07 pumps 448 FPS -34 FPS
10 pumps 515 FPS -40 FPS
12 Pumps 537 FPS -53 FPS
14 1/2" modified barrel
05 pumps 407 FPS -07 FPS
07 pumps 471 FPS -11 FPS
10 pumps 537 FPS -18 FPS
12 Pumps 568 FPS -22 FPS
A FT setup should make more power than my pump cup.
So should get 525+ FPS with 10 pumps, ATBE.
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FWIW
Picked up a few 13xx guns recently off eBay.
Resealed them and the 1322 made 450 FPS with 10 pumps.
Made an adjustable piston and replaced the stock breech and 10" barrel with an 18" barrel.
05 pumps 414 FPS 05.44 FPE
07 pumps 482 FPS 07.38 FPE
10 pumps 555 FPS 09.78 FPE
12 Pumps 590 FPS 11.05 FPE
Thanks Ron ;). If you can get those kinds of numbers with just a reseal and and an 18" barrel... my 1322 with the flat top is under performing by quite a bit.
The 18" barrel was counterbored and the port opened to .155", also used ice maker line for the TP.
Curiosity got the best of me so this morning in the name of science, swapped in an unmodified 14 1/2" LW barrel, then a counterbored 14 1/2" Crosman barrel with .155" port.
Referenced to the 18" Crosman barrel.
14 1/2" unmodified LW barrel
05 pumps 376 FPS -38 FPS
07 pumps 448 FPS -34 FPS
10 pumps 515 FPS -40 FPS
12 Pumps 537 FPS -53 FPS
14 1/2" modified barrel
05 pumps 407 FPS -07 FPS
07 pumps 471 FPS -11 FPS
10 pumps 537 FPS -18 FPS
12 Pumps 568 FPS -22 FPS
A FT setup should make more power than my pump cup.
So should get 525+ FPS with 10 pumps, ATBE.
this is interesting, thank you for the comparison. 8)
my LW unmodified barrel at 5 pumps seems to do a little better at 5 pumps, but not at 10. its like mine doesnt gain much with the FTP beyond 5 pumps comparatively to what you are showing with yours using the OEM valve and piston, strange. were these tests done with a stock TP or an opened up one?
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The unmodified 14 1/2" LW barrel had a stock TP and seal from a 13xx gun.
It measures .140", slightly larger than the barrel port.
Have you tested the gun since you pinned the valve?
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The unmodified 14 1/2" LW barrel had a stock TP and seal from a 13xx gun.
It measures .140", slightly larger than the barrel port.
the choking of the LW barrel has an impact as you mentioned earlier, but your using the stock TP versus my enlarged one changes things in comparison to your first test with the LW barrel. mine probably works out maybe a little better still at 5 pumps but definitely underperforming at 10. once i am able to finish my 1377 with the pinned valve and can compare it to the one that isnt, ill know more and have a clearer idea of what is going on with that 1377 and the 1322.
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The unmodified 14 1/2" LW barrel had a stock TP and seal from a 13xx gun.
It measures .140", slightly larger than the barrel port.
Have you tested the gun since you pinned the valve?
No, still waiting for the max flow TP from Alliance Hobby. I haven't enlarged the barrel port for it yet either on the LW barrel but have practiced that on a 10" barrel and feel I can do it without messing up the barrel. I won't do any work on my current modded 1377 until I have this new one done and tested. It may be under performing for the mods I did, but it is very accurate and still packs a decent punch. ;)
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Back in 2014 when I was GunNut10 on the now defunct Green Forum I modded a 1322 and got 595 FPS with 10 pumps.
Those were the days my friend, we thought they'd never end.
I think the link is still active out there so I'll have to see if I can dredge it up, the truth is out there....LOL
I have the back end of the aluminum valve with a pressed on steel washer from that gun.
Took it and added the top hat from a 2100 valve along with a new mid section so now it's a sharp dressed 3 piece valve.
The 2100 cap reduces the dead air space drastically for higher pressure.
Made a new Delrin stem and valve spacer to reduce the valve volume to about the same as a 2100 valve.
Replaced the 70 duro valve seal with a 90 duro poly seal.
Also made a new bolt probe but it didn't change anything, just looks better.
14.3 CPHPs, 18" barrel:
05 pumps 427 FPS 05.79 FPE
07 pumps 506 FPS 8.13 FPE
10 pumps 589 FPS 11.01 FPE
12 Pumps 625 FPS 12.40 FPE
Makes 18 FPS per pump from 10-12 pumps and has a nice little kick.
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my pistol with a 13 inch barrel and a different spring and some polishing of the trigger, and original valving will push crosman premiers at 495 fps with 11 pumps (i do eleven as 10 will only do 482, and at 11 it will still dump all the air. original barrel and same mods did an honest 463 fps at 10 pumps.
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A few things to check:
Ensure the piston is clearing the top of the slot when the pump arm is fully open.
With an adjustable piston and wear it can be set so that it can't intake air fully.
Pump the gun 10 times and open the pump arm.
If it springs past 30 degrees there's too much dead air space.
Since you're counterboring the barrel then do the same to the valve.
You can then use .170" ID ice maker line for your TP.
Here's my 1322 Medalist pump arm with 10 pumps.
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A few things to check:
Ensure the piston is clearing the top of the slot when the pump arm is fully open.
With an adjustable piston and wear it can be set so that it can't intake air fully.
Pump the gun 10 times and open the pump arm.
If it springs past 30 degrees there's too much dead air space.
Since you're counterboring the barrel then do the same to the valve.
You can then use .170" ID ice maker line for your TP.
Here's my 1322 Medalist pump arm with 10 pumps.
Thanks Ron, I will check the degree of the pump arms when at 10. I have had to rethink my plan for this 1322. I can port the barrel to match the max flow TP but i just dont have the means to do the countersink around it. That is the part I am not comfortable with. what I have learned from all of this is that a widened TP is of no value either in a 1377 or a 1322 unless the barrel is ported to match it. I still have my 14.6" Crosman .22 barrel I can port then try and find some way to touch up the countersink around it. if i can manage to do that on my "practice barrel"... I will revisit this on my 1322. in the mean time, all three of these builds will be going back to the Crosman .140 TP. I need to get this newest 1377 wrapped up and done so I can compare it to the other 1377 build I did. this new 1377 build will tell me what, if anything i have done, will get me where I would like to be then apply those things to the 1322. ;)
ok, so this is interesting...
mine (the 1377 modded one) is definitely farther open than yours at 10 pumps, more than 30 degrees. i adjusted the piston out because the pump arm was popping open too easily when i pick up the gun by the pump handle. what is interesting about this is i just put a pellet through it at 10 pumps and got 612 FPS, and another pellet at 11 pumps and got 617 FPS using the 7.4Gr super points? that is 25 and 29 FPS more than it was before i adjusted the piston and it is above the 30 degree pump arm angle... very strange? I am actually not unhappy about this... it got over 600 8).
So if the pump angle is too far, then i need to go back in a little on the piston adjustment, correct?
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Sounds like you're making progress.
The pump arm on my 1322 opened almost 90 degrees after reseal and 450 FPS.
There was a lot of dead air space with the fixed plastic piston.
How far the pump arm opens is an indication of how efficient the gun is.
Ideally all the air from each pump should go in the valve.
In reality there's always some dead air that acts like a spring.
Adjust the pump arm so you can just feel the piston touch the valve with about 1/2" before the arm fully closes.
Replaced the piston and barrel support on my 1322.
Bumped up velocity some.
14.3 CPHPs, 18" barrel:
05 pumps 439 FPS 06.12 FPE
07 pumps 515 FPS 08.42 FPE
10 pumps 604 FPS 11.58 FPE
12 Pumps 650 FPS 13.41 FPE
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Sounds like you're making progress.
The pump arm on my 1322 opened almost 90 degrees after reseal and 450 FPS.
There was a lot of dead air space with the fixed plastic piston.
How far the pump arm opens is an indication of how efficient the gun is.
Ideally all the air from each pump should go in the valve.
In reality there's always some dead air that acts like a spring.
Adjust the pump arm so you can just feel the piston touch the valve with about 1/2" before the arm fully closes.
Replaced the piston and barrel support on my 1322.
Bumped up velocity some.
14.3 CPHPs, 18" barrel:
05 pumps 439 FPS 06.12 FPE
07 pumps 515 FPS 08.42 FPE
10 pumps 604 FPS 11.58 FPE
12 Pumps 650 FPS 13.41 FPE
yep, a little progress in the right direction and i didnt do anything but adjust the piston, lol. when i assembled that build, i adjusted it just like you said... until i felt it make contact with the -ring off. it felt right? it was even about 1/2" from full close and it locked over fine... but just bumping the arm would cause it to pop open? im close though 8). once i get back in to that one to pin the valve, debur, some shimming, and do a few other little things like the spacer you pictured... i wont fully reassemble it until that part is right. im just excited i finally saw it go over 600 FPS, lol. ;D
this piston adjustment i made, i did with it assembled, completely assembled. it was not easy... i wont try that again, lol.
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with the new 1377, this is where i am...
(https://i.imgur.com/NUAsap3.jpg?1)
the piston (without the o-ring) just touches the now pinned valve. based on pictures Bentong posted in an older thread i did... this looks correct and it locks down nicely. once i get the flats added to the sides of the hammer (hopefully at work tonight) then polish it, i will get the lower done and check the angle at 10 pumps and adjust from there. I am a little anxious to get this one done so i can get back in to the 1322. ;)
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back on track...
took the 1322 apart this morning and began its upgrade "re-do". right off the bat i found that the breech set screw had worked its way loose. the second thing i found was when i removed the flat top piston, it was pretty clear that the piston had pushed back against the raised notch it sits against. not very far, but enough that it left a light impression of the notch in the seat of the valve. the screw that holds the barrel tight in the barrel band was loose as well. that one was probably my fault for not rechecking it during final assembly.
the pump tube is now completely deburred and I already put flat spots on the side of a spare hammer a few days ago at work then sprayed it with dry lube. i gotta give the tube a good cleaning, then valve pinning is next. 8)
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Past experience with these guns has led me to a better way to tighten the breech screw, so it stays tight.
After starting the breech screw,, place the comp tube / breech assembly, lengthwise, in a padded vise, tighten the vise. THEN tighten the breech screw.
You'll be surprised at how much better the breech screw will hold.
I believe it has to do with being able to fully compress the transfer port seal, with the vise, versus trying to compress it with that tiny screw.
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Past experience with these guns has led me to a better way to tighten the breech screw, so it stays tight.
After starting the breech screw,, place the comp tube / breech assembly, lengthwise, in a padded vise, tighten the vise. THEN tighten the breech screw.
You'll be surprised at how much better the breech screw will hold.
I believe it has to do with being able to fully compress the transfer port seal, with the vise, versus trying to compress it with that tiny screw.
Thanks Scott... great idea and I have some hard plastic hand Rachel vises that will work very nicely for that. 8)
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got the valve pinned yesterday and the trigger frame back on. waiting on Mellon air at this point. his spacers for the pump arm are excellent. i have the piston adjusted correctly to the valve now. i can reassemble a few more things then just have to wait, but im over the hump. 8)
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My order from Mellon Air finally arrived yesterday and i got the forearm spacer i was waiting for. the 1322 is now back together and pump arm correctly adjusted... looks perfect and pumping to 20 left no residual air in the valve. i went back to the stock TP since i am not ready to try barrel porting, and i didnt do anything additional as far as mods go. pinned the valve, debur, polish, put flats on the hammer, adjustments... that's it.
should be able to run some chrony tests in a day or so. ;)
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Hi Ron,
My 1377 with GMAC FT internals goes past the 30 degrees after pumping tem times and releasing the pump arm.Is that harmful ? inefficient ?How do I rectify it ?
Manish
A few things to check:
Ensure the piston is clearing the top of the slot when the pump arm is fully open.
With an adjustable piston and wear it can be set so that it can't intake air fully.
Pump the gun 10 times and open the pump arm.
If it springs past 30 degrees there's too much dead air space.
Since you're counterboring the barrel then do the same to the valve.
You can then use .170" ID ice maker line for your TP.
Here's my 1322 Medalist pump arm with 10 pumps.
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Hi Ron,
My 1377 with GMAC FT internals goes past the 30 degrees after pumping tem times and releasing the pump arm.Is that harmful ? inefficient ?How do I rectify it ?
Manish
A few things to check:
Ensure the piston is clearing the top of the slot when the pump arm is fully open.
With an adjustable piston and wear it can be set so that it can't intake air fully.
Pump the gun 10 times and open the pump arm.
If it springs past 30 degrees there's too much dead air space.
Since you're counterboring the barrel then do the same to the valve.
You can then use .170" ID ice maker line for your TP.
Here's my 1322 Medalist pump arm with 10 pumps.
Im not familiar with GMAC valve but if it has an adjustable piston, you will have to take out the pump arm with the piston, adjust it in, then check it. you may need to do this a time or two to get it set correctly. it isnt harmful that im aware but it is inefficient. ;)
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Chrony is done using Crosman super points, 14.3 grain at 10 pumps...
488 / 7.6
489 / 7.6
487 / 7.5
492 / 7.7
488 / 7.6
very consistent 8). with the FT setup and all the corrections, still not above the OEM "up to" 500 FPS but with the choked LW barrel, it probably would be? it is as good as it is going to get. it's decent though. time to call it done, get it scoped and sighted in, and move on and get all this done to my original modded 1377. 8)
i did one shot at 5 pumps and it was 385 / 4.7.
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I just have my 1322 fully stock but I want to mod it a little.
Was thinking I wanted to keep it a pistol grip with maybe a 14.5”-18” barrel and fiber optics sights.
I Think I will custom make my own wooden pumper that extends half way over the trigger guard to make it that much easier to pump it. My palm starts to hurt after smashing it into the trigger guard, so the custom pumper should solve that issue.
I was thinking about trying to drill out the OEM sights and insert a fiber optic rod.
The whole idea for my 1322 is to stay small enough be able to toss it into a backpack/bug out bag, but NOT for my 1322 to live in a bug out bag. To many gophers and such need regulating ;)
Thank you for this thread, it’s been very helpful!!
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so in looking at my first thread... it seems to be lower at 5 pumps then it was but higher at 10. interesting but still a done deal. i keep thinking this gun is rated up to 500 but it is actually 460 FPS, lol. with where it is... i'm good. 8)
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s rated up to 500 but it is actually 460 FPS
You'll be amazed what you can do with 400+ fps in .22 within 20 yards. i have gone back to open sights to make sure that i dont feel "overconfident" and try that squirrel at 35 yards... because if i can get in to 20, its toast, or better yet, dumpling...