GTA
Airguns by Make and Model => Crosman Airguns => Topic started by: MountainMan126 on December 09, 2011, 08:02:34 PM
-
I have recently developed a need to upgrade my garden defense tool. I have had a bunch of pc77 take-off parts hanging around doin' nothing and a 16" barrel that was not up to par on arrival. After seeing a post recently on another members 1377 build and the numbers potentially possible with some new ideas on low volume high pressure mods, I got started a few days ago with what I have on hand.
My goal is to build a very wallet friendly, still pistol shaped replacement for the current rifle.
I will have to buy some of the parts I need, a metal breech is the first that comes to mind. On hand now I have the barrel , .177 cal. , and 16" in length. I just did an at home re-crown on it today, looks decent but once together we shall see what the paper says. This is gonna get painted when done.
I did a lot of work on the valve, the reference pics and write up I had were great. I made a few changes here and there, but followed a similar idea , lower volume, higher pressure. I chose to cut the stock spring to the desired length, and while not a lot, I did enlarge the inlet port for easier pumping. I also enlarged the exit port inside, but not down from the top so it will still use the factory seal. Mine is not a flat top since that would require buying/making a piston, Maybe another time. I added an oring to the front of the piston behind the cup to get it a better seal against the valve , and against the wall of the tube.
I got some dicks sporting coupons in the mail. If they let me combine them I can save 20 off a new 1377. Get it down around the price of a refurb w/shipping.
-
Good luck on the project. Keep us up to date and throw up some pics.
-
Thanks , I have big hopes for all the valve works pending a sealed pressure test. I am still working out an extended bolt idea and a few others.
-
1377 build-off just started on the Green Crosman forum.
http://www.network54.com/Forum/275684/thread/1323299777/2012+1377+Build-Off+Announcement (http://www.network54.com/Forum/275684/thread/1323299777/2012+1377+Build-Off+Announcement)
-
I can't see myself in too many more forums, I just don't spend enough time on the computer to keep up with everything. I would be happy to steal this idea and build-off 1377s here. Anyone else up for some friendly competition?
-
that would be a neat idea
-
since you are not flat topping yet!
you can stuff the stock piston add an o-ring under the pump cup and shave a little of the point off the valve face for a better fit in the cup
you will see some gain from those mods!
-
since you are not flat topping yet!
you can stuff the stock piston add an o-ring under the pump cup and shave a little of the point off the valve face for a better fit in the cup
you will see some gain from those mods!
Thanks , already did it. I went to Dick's today and they will combine coupons. I got the 1377 brand new for a shade over 50 bucks. Chrony testing soon to get a start point and then tearing it down to put my valve in and should have the piston done tomorrow. I am working on a way to make it more rigid, so it will flex less under higher pressure.
-
OK guys, I know we are all familiar with what these look like, but here is the brand new unaltered start pic.
(http://inlinethumb44.webshots.com/47723/2226546780105435861S600x600Q85.jpg) (http://sports.webshots.com/photo/2226546780105435861dLLoBy)
This is the power adjuster I made, I used the original piece from the back and drilled all the way through, 5/16. Then tapped all the way at 3/8-16 and spent 70 cents for the set screw at the hardware.
(http://inlinethumb10.webshots.com/24841/2799583260105435861S600x600Q85.jpg) (http://sports.webshots.com/photo/2799583260105435861PxOjYS)
I will post more pics and chrony #'s as we go.
Ethan
-
alrighty then!
sound like you are on the right track!
-
I saw a post at some point that referenced using metal rods on the outside of the piston to stiffen it for less flex during pumping. I don't know where I saw it, but I haven't been able figure out a good method of attaching them where it will be secure enough to use. So I came up with this and drill a hole 5/32 straight down the middle and threaded this screw all the way through. Some light sanding on the base of the pump cup to clear the head, not much with the o-ring in there to space it out. A dab of adhesive on the top to make up for any lost friction having the pump cup spaced out from where it usually sits and here it is.
(http://inlinethumb11.webshots.com/49610/2069389350105435861S600x600Q85.jpg) (http://sports.webshots.com/photo/2069389350105435861oeTdGf)
(http://inlinethumb48.webshots.com/48111/2655876940105435861S600x600Q85.jpg) (http://sports.webshots.com/photo/2655876940105435861cxSBDp)
Anyone else done this, any documentable results, hunches?
Thanks , Ethan
-
hey mountain man, could you post some more pics of the whole gun please
-
The current pic is accurate, I have been modifying all the take off parts from my last project to use on this one. I want to get the chrony numbers of everything perfectly stock so I can have a start point and see what has an effect and how much. I will post plenty of pics as I go. Should get some more up tomorrow.
-
I saw a post at some point that referenced using metal rods on the outside of the piston to stiffen it for less flex during pumping. I don't know where I saw it, but I haven't been able figure out a good method of attaching them where it will be secure enough to use. So I came up with this and drill a hole 5/32 straight down the middle and threaded this screw all the way through. Some light sanding on the base of the pump cup to clear the head, not much with the o-ring in there to space it out. A dab of adhesive on the top to make up for any lost friction having the pump cup spaced out from where it usually sits and here it is.
(http://inlinethumb11.webshots.com/49610/2069389350105435861S600x600Q85.jpg) (http://sports.webshots.com/photo/2069389350105435861oeTdGf)
(http://inlinethumb48.webshots.com/48111/2655876940105435861S600x600Q85.jpg) (http://sports.webshots.com/photo/2655876940105435861cxSBDp)
Anyone else done this, any documentable results, hunches?
Thanks , Ethan
it called stuffing the piston
i used a very stiff rod about the size of a metal clothes hanger
cut it down ,a little longer than the slots in the plastic piston, leaving points on the end of the rod pieces
press them in the points lock the rod in place
i did see some gains cant recall right now what they were
ill try to find the post i put the results in
-
First I will qualify by saying this is not a permanent addition, more an excercise in seeing if I could do it. This is the stock bolt and will only fit the plastic stock breech. I am hoping to get some info on extended vs. flow through in 177 , and will probably order the nicer looking product from Mellon air when I get a metal breech.
But in the spirit of " If you can you must " , here is the at home bolt extension. I used the dremel to make a dip in the center to keep the drill from walking, and the made a hole as deep as I thought I could without breaking the end off. Cut a piece from a broken drill of the same size, and made the first half of the hole larger to accomodate more epoxy. A little sanding and here it is. It is not pretty, but it is good for free.
(http://inlinethumb26.webshots.com/50393/2238537150105435861S600x600Q85.jpg) (http://sports.webshots.com/photo/2238537150105435861rUNoqu)
(http://inlinethumb44.webshots.com/50091/2467593480105435861S600x600Q85.jpg) (http://sports.webshots.com/photo/2467593480105435861cvfiMM)
Thanks for the info 1377x , I knew there had to be a name for it.
Ethan
-
Hi All:
Let me start off by stating great thread. I had read the same article and the four rods were cut to size and epoxied in place. Mountain Man on your power adjuster how long was your 3/8 set screw and how many turns in to get the adjustments you were trying to get.
Thanks
4Th Yote
-
Hey 4th yote, The set screw is short maybe twice as long as what is show in the photo. Is cut to a point on the forward facing side to seat on the spring with no additional grinding etc. From what I can see the position in the pic should put little to no tension on the stock spring, and be adjustable inward for more pre-load from there. I used 3/8-16 coarse thread because it was an easy fit to the hole sizing available , and has a better selection of hardware. I can get you better pics from the inside etc. if you want them.
-
In an effort to remain as scientific as possible I will do all chrony numbers with CPHP ammo and worry about what it likes the best once complete. All numbers taken at 10 pumps. So here are the stock numbers I got right out of the box.
1-488.4
2-491.6
3-484.2
4-499.9
5-497
Average-492.18 FPS
Total deviation-15.7 FPS
-
Mountain Man:
I would like to see additional pix. Now tell me how much energy you will expect to get by using this power adjuster?? I just saw your refurbed bolt and upgraded piston are there any plans to do a flat topped valve as well??
4Th Yote
-
I installed the power adj. and it does not seem to have a huge impact on velocity. Numbers are bery similar to stock. I think what this means is that the factory spring does not generate enough force pre-loaded or other wise. This will get the disco spring eventually.
(http://inlinethumb49.webshots.com/47856/2693950280105435861S600x600Q85.jpg) (http://sports.webshots.com/photo/2693950280105435861hadvYH)
I have made a ton of mods to the valve, will post pics and right up on mods pending successful install and pressure test.
-
Mountain man:
Good pix of the adjuster but now I have another question. Having just got back from the hardware store I got the 3/8x16x1/2 set screws. They have a taper to them already so this means you ground off more on the set screw to match the opening of the spring. Why wouldn't it be easier to put a small flat washer in front of the set screw and make adjustments that way and not worry about deforming the end of the spring.Would this increase power a bit more,being able to compress the spring more with out spring damage ???
4Th Yote
-
The taper mine has I thought was sufficient, and did no additional grinding or shaping of the point. Just got done installing the new bolt. I think it shows a modest increase in FPS, but numbers are still fluctuating. My guess is the ammo will be differnent once I run through a bunch of different types of lead and find the one it likes best.
Best with new bolt was 518
-
518 FPS was a fluke, I don't think I pumped it an extra time or anything . However I have been getting much more consistant numbers. Getting it down to an aver. of about 495 with +/- 3 FPS either way. Next is goiing to be the valve and piston install, I am hoping for major improvement with these parts. I will not have time to do this until tonight or tomorrow, as I must go to work at some point.
-
Plan change , when I ordered the disco hammer spring for my first build, I bought second in case. If that one wore out at some point or I did a second build and wanted the same option. Well I found where I put it this morning, so that will be the next thing. About 2 bucks direct from crosman , plus for $4 in ship/hand and whatever else you put on the order. I will swap that when I get home and have to re-chrony in the morning . I need daylight for that , and am not set up do any of that sort of testing indoors.
-
(http://inlinethumb34.webshots.com/36961/2241435060105435861S600x600Q85.jpg) (http://sports.webshots.com/photo/2241435060105435861Azwlbz)
The disco spring is the one on the bottom , nice easy change with the adjuster. Just pull the screw , drop old spring out the back , add new one reinstall the screw and done.
-
mountain id you used a longer screw in the adjuster i would put more load on the spring, we used to do this with our paintball guns and the refs at the field found out would not lut us use them and we had to take the longer screws out. ....
-
mountain id you used a longer screw in the adjuster i would put more load on the spring, we used to do this with our paintball guns and the refs at the field found out would not lut us use them and we had to take the longer screws out. ....
Having a longer screw will only have more hanging out the back, not give you any more adjustment from what I can tell. I have done chrony testing with this screw in all positions with the stock spring with no legit. change. I don't think the stock spring is strong enough against the air pressure in the valve at 10 pumps.
Tonights work is a smoother , lighter trigger. Original spring is in the pic on the right. I used the front tapered section from a click top bic pen , cut both ends with razor, turned the brass thumb screw with smooth top [8/32 thread] through the middle and trimmed flush with a dremel tool. I cut a lighter weight spring down to fit , a little fine tuning and it is done. Tested several times , feels nicer, and maybe a little more than 1/2 the original weight, but I don't have an accurate way of measuring.
(http://inlinethumb26.webshots.com/20441/2962018430105435861S600x600Q85.jpg) (http://sports.webshots.com/photo/2962018430105435861FyWOMh)
(http://inlinethumb34.webshots.com/48929/2325109940105435861S600x600Q85.jpg) (http://sports.webshots.com/photo/2325109940105435861UMVSUA)
-
Chrony testing with disco spring reveals no significant change in velocity. I think next maybe the barrel, and then the valve and piston. New trigger work is sweeeeeeet!!!!!
-
Hi All:
Mountain Man again nice work. Its a shame that the disco spring didn't increase anything.I to did some trigger work on my 1377 and went about it a little different. First went to local hardware store and got a #90 spring then cut 5/16"off the end then inserted a spent 22 cal. case inside the spring and put it back together. This made for a smoother trigger. I Then drilled a #29 hole in the trigger guard and tapped a 8-32 set screw to make a trigger stop -works great with no backlash from the trigger.
4Th Yote
-
Very cool 4th yote, do you think the 22 being flat on top is an advantage? In comparison to mine which is rounded. Today I drilled out the barrel band and added a 16" at home recrowned barrel [face could be polished more]. I will clean and test fire tomorrow. I ran out of time having to take some time to skin a beautiful black squirrel I took this morning. Fleshing when I get home and into tanning solution.
Anyway here are the barrel pics, hole is drilled to what I think is a perfect fit. So snug I didn't use any adhesive. Drilled from the backside into a maple block with a colt fluted bradpoint 7/16 drill bit.
(http://inlinethumb03.webshots.com/31490/2185058370105435861S600x600Q85.jpg) (http://sports.webshots.com/photo/2185058370105435861nSlwiF)
-
Hi All:
Mountain Man I don't know if there is any avantage between your and my set up.I went with the 22 case just because its flat and has more contact surface,its cheap to replace. Nice job on your barrel that is my next step on my mod list but got to wait till MellonAir has them in stock. I figure a nice 14.5" barrel w/muzzle brake should get me a least another 8 FPS.
4Th Yote
-
Hey 4th yote, many thanks on the trigger stop mod. I did mine tonight as you suggested, drilled the hole [gettin' by with a 1/8 bit, do not own a #29] and tapped 8-32 . Installed a stainless set screw, a dab of blue locktite, a little fine tuning to get it set to stop the trigger movement right after the shot breaks. No more over-travel after the shot, and I thought the trigger was good before, what a difference. I will let it cure over night and shoot tomorrow.
(http://inlinethumb24.webshots.com/46231/2328970890105435861S600x600Q85.jpg) (http://sports.webshots.com/photo/2328970890105435861EWQZFw)
-
All right , got up , got the chrony, gun and ammo. New test results are as follows with the barrel. Previous was about 495 FPS, all other factors the same except the barrel, finally gettin' somewhere!!!
10 pumps
CPHP 7.9gn
Average=548.5 FPS
Standard deviation=2.0
FPE=5.27
Noise out put is greatly reduced with longer barrel. I also believe I may see greater effects from the power adjuster since now I have the barrel length to use any extra air released from tightening the hammer spring adjustment.
-
Hi All:
Mountain Man glad you liked the trigger stop mod. Now I have to go on a little tanget about the power valve. First you weren't looking to increase FPS or FPE right. What I thing you are trying to do and tell me if I'm wrong is to put enough pressure on the hammer to remove any gap between the hammer face and the valve stem face.This I think will dump the compressed air faster.Now trying to adjust the original spring didn't get any results,so you tried using a disco spring and still no promising results. Let me now throw a wrench into the works here. What if you could find a spring with the same length,have more tension,and be able to slide over the existing spring. Would this double spring combo be able to acheive the results you were looking for?? let me know if I'm half baked or not.
4Th Yote
-
My use of the power adjuster is not so much to gain FPS/FPE , but to set it to pre-load the hammer spring with the minimum amount of tension and still dump all the air in the valve. Therefore eliminating any un-needed spring compression while in storage.
As far as double springs, I think it may bind and be less effecient than one stronger spring.
-
mountain man i would put as much pressure on the spring ad you can without the adjuster crushing the spring this will give you the most force in the hammer and then run it across the crony backing the screw back out until you notice a drop in velocity.if your not preloading the spring enough you will not dump any More air in the valve possably leaving air in the valve. what you want is for the spring to allow as much air to leave the valve as possible. a heavier spring is not always the answer as it could keep the valve slightly open, i am not familiar with the 1377 but it uses the same principals as my pb gun
-
(http://inlinethumb07.webshots.com/49478/2303733010105435861S600x600Q85.jpg) (http://sports.webshots.com/photo/2303733010105435861KyjOyD)
Not a huge mod, but a big difference. Ambidexterous grips are for people who appreciate having options and not having any one particular really good option. A little time spent with a shaping file and sandpaper , and I have eliminated the left hand thumb shelf. Way more comfy, no money spent.
Muppit , I agree to get max power from the adjuster I should crank it in as far it will go. My goal is longer more consistant spring life, storing at max usuable compression should reduce the over-all spring length over time and should eventually result in a weaker hit. JMHO
Ethan
-
i agree, i misunderstood your goal i thpught you were searching for more power aout of the build ,which you are but you also want dependability.
-
Hi All:
Well I got my power adjuster adjusted.I ran the set screw in all the way until the bolt wouldn't cock, then I started backing it off until the valve dumps all the air and be able to cock the bolt. I'm not able to hear the bolt click as it is being pulled backwards but does work. I also used a heavier spring #44 cut to original spring size - it didn't work to stiff so I'm using original spring. One feature that I liked was using the 3/8x1/2" set screw I can adjust power valve using only my fingers - good bye allen wrench. All for now.
4Th Yote
-
Good deal 4th yote, I cock the gun , and then run the screw all the way in until snug. Then back out 3/4 of a turn and call that max power. Cocks at this point first time every time. Then over the chrony and shoot 3 times and back out a half turn. This is where the allen wrench comes in handy, I use the end facing me like a clock hand to get accurate half and full turn adjustments. Repeat until there is a noticable change and turn back in 1/4- 1/2 turn to account for any loss of tension when the spring takes to it's new position. This is what I consider to be ideal in the sense , you haven't loss FPS from the max position and are no more than a half turn more than the minimum required to hit peak fps. Depending on the spring weight and length will depend on how far you can go with backing it out with no change.
I can not back this up with published materials, just thinking out loud on what I think makes sense.
Ethan
-
Hi All:
I just had the chance to test this 1377 out on some live game. One pidgon zaped!! With the adjustments on the power valve and with the adjustments to the trigger this carbine seems to be alot smoother in operation than expected.Even the pumping action seems to be alot smoother than normal?? At 7 pumps I took this park rat at 50ft. using crosman destroyer ex one shot to the fuse box and lights out.
4Th Yote
ps: neighbor behind me loves fresh squabb lol
-
That's what I like to hear! Park-rat headshot at 50 is good any day.
I will have finished pics of grips tonight. The topcoat is drying while I work.........or am at work as the case may be. Still have a bunch more mods coming that are just about done. I keep gathering ideas and materials as I go. New foregrip is high on my list to get done.
-
Hi All:
Hey Mountain Man I hear ya on the forearm grip. I need a router so I can make forearm to look like a 760 - big and boxy. The purpose of this style is if I leave a 1/4" of material on the bottom I can mount a weaver rail to the forearm. Then I'll mount bipods for assault,vertical grip for tactical,and flashlight for cqb. LOL
4Th Yote
-
looking forward to see the grips
-
(http://inlinethumb35.webshots.com/50082/2249070460105435861S600x600Q85.jpg) (http://sports.webshots.com/photo/2249070460105435861wdDxVQ)
Grips are done, again trying to do as much on my own, and with the original parts as possible. I made them right hand specific and scuffed all the remaining smooth areas with 150 grit. Then outside and sprayed down with rubberized undercoating. A little better texture than hard smooth plastic, should have good adhesion without primer. It is also paintable and tough as nails.
4th , I have a different approach to the foregrip, and right now includes a weaver mount as well.
-
Front sling mount made from a shaft collar, about 2 bucks at the hardware. A 10/32 thread sling mount, cut down and threaded all the way down. You can drill the hole for this thread tap with a 5/32 bit, but you should use a #21. Red thread locker on this stuff. Use a standard quick release mount. 2 bucks in nylon webbing from the fabric store and some snaps, so I don't have to learn to sew just yet.
Is drilled off to the right on purpose so it hangs out of the path of the pump stroke naturally.
(http://inlinethumb30.webshots.com/48605/2950658230105435861S600x600Q85.jpg) (http://sports.webshots.com/photo/2950658230105435861yWbZtO)
The rear mount is easier , one screw style base chrome snap , commonly available from the hardware . Some very slow careful drilling and mounting. Lockwasher, and red lock tite here. Once the cap was pressed on to the sling I had to file the mating part on the gun to get it seat nicely. But now it is done and I have a very funtional , quick release system home made sling.
(http://inlinethumb07.webshots.com/39174/2099463470105435861S600x600Q85.jpg) (http://sports.webshots.com/photo/2099463470105435861XVCzmX)
Enjoy , I think this is a good one , especially since it hides the divet in the top of the longer crosman barrels. I think it must be a sight alignment point or something, but it is gone now .
Ethan
-
I am really digging this build
-
I am really digging this build
Thanks ,I think so far having gotten the gun at a good deal, and having paid too much for the barrel. With extra parts I have probably spent about 100 bucks to make everything. I have not bothered tracking how much time I spent on this, it is probably better that way.
-
Hi All:
Mountain Man nice sling. I made my sling a single point style for under $1.25. I would post pix here but keeps telling me my file is to big to post. Might have to join photobucket.
4Th Yote
-
Hi All:
Mountain man I see that the set screw on your set collar is facing in the up position. Any chance you could remove the set screw and replace with one of those screw in type of sight post??? Just a thought.
4Th Yote
-
4th , I use webshots for my photos, i can paste at 600 pixels. You can also click the photos in the post and view fullscreen at their site.
The set screw on top is a large coarse thread, If you mount in a different position and drill and tap 8-32 you should be able to thread in and use most of the common pins from an archery sight.
-
A friendly reminder, you can machine Delrin on a mini wood lathe like for pen-making. This is a lot cheaper and easier to store than a metal lathe and some local woodworking places offer free intro classes to get started.
I had my wife take the pic so you can see the set-up. Clamp the original gun barrel in the chuck. Cut and drill the stock 7/16 all the way through. Drill and tap the 8/32 set screw hole in the side that with hold it on the gun. Use the set screw on the barrel in the lathe and the live center to keep and true round motion and cut to what ever shape you want . I drilled a snug hole in the top and cut a nail down to have a center bead like a shotgun ramp. The sight is usually 15 bucks at dicks , I got one of the $10 rewards coupons, out the door for a little over 5.
(http://inlinethumb46.webshots.com/47661/2090259490105435861S600x600Q85.jpg) (http://sports.webshots.com/photo/2090259490105435861ePordX)
This is the finshed muzzlebrake with front sight mod. You can polish as much as you want , I liked the matte finish, with the scratches . Total cost on this is about 20 bucks without the coupon, I have a good place to buy raw materials though.
Watch out where ever this double sticky tape touches is where it will stay.
(http://inlinethumb33.webshots.com/43808/2422693340105435861S600x600Q85.jpg) (http://sports.webshots.com/photo/2422693340105435861wNjYpZ)
-
is there any reason you couldn't do that on a larger wood lathe? I imagine it would work just as well, but figured I should ask.
I've got a 14x40 sitting in storage.
where would you suggest buying delrin?
-
No ,a larger wood lathe will do everything I can do better. They are heavier , which translates to less vibration etc. I get stuff like that from a industrial plastics company that is local for me. I am sure you could buy online. For stuff like this I get round stock, didn't want to bother cleaning corners off square stuff.
-
I figured I should shoot a little instead of just building stuff. New muzzle brake doesn't change POI except the site sits higher than the original ramp so some adjustment was still needed. Interesting as it may be , the brake goes approximately 1/2 inch past the muzzle and is a clean 7/16 hole straight out. Still it changes the report, a little louder and a little more a harsh , a crack would be accurate.
-
I wish I had taken the stock info for comparisson , if anyone has an accurate weight for a stock 1377 please post.
This one as it currently sits , sling , longer barrel, muzzlebrake and all at 2lbs 6.8oz on a digital postage scale.
-
Solid pin , I forget what they call the pin at the hardware, hitch pin? Either way it has a detent ball to hold in place, once it wears in I may shim with a washer. I cut the end with the hole and ring off and tapped threads at a 1/4-20 , added a brass acorn nut and done.
(http://inlinethumb36.webshots.com/49891/2453292950105435861S600x600Q85.jpg) (http://sports.webshots.com/photo/2453292950105435861vpgEFt)
I drilled the pump arm separate, and from each side independantly. Did the pump tube and plastic together, again each side independantly with a 1/4 inch plastic wedge cut, and shoved in the middle so it wouldn't flex too much while drilling. Once all the holes were drilled I passed the bit clean through everything.
(http://inlinethumb43.webshots.com/49706/2943292540105435861S600x600Q85.jpg) (http://sports.webshots.com/photo/2943292540105435861pLbwFt)
I know there is some conventional wisdom against drilling any metal out of the pump arm, but it is a clean hole all the way through that now has greater contact area, smoother surface without the roll pin and the ability to be greased. So I am hoping to reduce wear and friction, pump stroke is super smooth right now. No rattles, no side to side motion, really feels prefect, but I will keep you posted on any problems or reinforcements needed as I put the shots through.
-
is there any reason you couldn't do that on a larger wood lathe? I imagine it would work just as well, but figured I should ask.
I've got a 14x40 sitting in storage.
where would you suggest buying delrin?
Try here >> http://www.onlinemetals.com/merchant.cfm?id=203&step=2&top_cat=181 (http://www.onlinemetals.com/merchant.cfm?id=203&step=2&top_cat=181)
-
Awesome sling and brake!
Ernesto
-
Thanks BigErn, I am trying a lot of new stuff with this build. Having done the one in my sig. with mostly purchased and bolt on type mods gave me a whole bunch of spare parts. Not to mention a lot of ideas seeing how others have made these upgrade components with fancier equiptment. Not everything I have tried here has been a complete success but it has all been educational , case and point is the grips. I love the new shape by comparisson, but am starting to think the rubberized undercoating will not hold up under the repeated abuse from pumping. I will probably make new ones from wood, got a bunch of scraps of different types hanging around from other projects.
Thanks Bentong, I have bookmarked this website as well. There is never enough money, storage space, or places to get fun stuff work with.
-
I tried 4 different types of pellets , will shoot and group all well. Does seem to have the tightest groups with CPHP which is fine by me. Also tried Superdomes, Daisy HP, and Skenco ultra shock hp. As I see it, if the lady is willin' ta drink NightTrain, ain't no good reason to get her hooked on the fancy stuff.
-
Tried out the valve today, not a big success or failure. I ported the inlet, flattened the nose where it seals to the cup, reshaped the inlet seal to be dished on the back, added a ball bearing to take up space. Then shortened the stock spring, ported the exit chamber and shorten the stem that comes out the back. Installed with new piston and no leaks. unfortunately also chronied at stock velocity, I tried as many different combinations of new and old parts, ported not ported, short spring , stock spring , with and without the bearing. The 2 best setups are the stock piston and valve , and the ported valve with with stock internals. I have had this apart and back together so many times today I don't have any idea.
-
It appears I did have a small leak, has been repaired. Now I have the original piston , valve front and seal. Different spring inside and ported back end , with shortened rear stem. Sounds good when pumping, dumps all the air at 10 pumps, it won't do that now with the stock hammer spring. So I guess the disco spring is needed after all. Spring inside the valve is the one from the trigger originally, with the porting I also flattened the inside where it seals at the back and in doing so lengthened the spring area.
Trigger spring sits better than the one I took out, almost clicks into place on the valve parts at either end.
537 with superdomes / 545 with cphp
-
Questions for anyone regarding the high pressure low volume set up. Is this really effective ?
I have tried several set-ups now , all of which leak after the stroke is complete, and only after 3-4 full strokes in . If I had to guess it leaked out the way it came in. Do you guys increase spring tension inside the valve to hold greater pressure ? Mine had about 15lbs by the bathroom scale. At ten pumps would hold after the leak and shoot about 485 fps.
Yes, I cocked it to relieve any hammer pressure on the valve, no it is not coming out the barrel.
My current set up is a stock piston pump cup assembly. into a stock valve front with original plastic seal. Spring from the original trigger [stiffer, fewer coils] uncut, into modfied back and tail. This should have more volume than stock, but lower pressure with each stroke. Still shoots close to the same as the stock valve with everything else the same, barrel etc. at 10 pumps. Do I have reason to believe pressure would yield it greatest benefit in a pistol that lacks the barrel length to make use of volume?
Finally we get to the BIG question , if I pump this 5 more times for a total of 15, in theory I am compressing 50% more air into the same space , which on it's own should have a significant effect on pressure, FPS 545 at ten pumps, FPS 581 at 15 , does not leak either way. Clearly not a 50% increase in velocity,I was not expectin it either, so how much does this actually yield when sealed properly.
I know their are some who claim in the 700-800 range with a .22 cal., I have been realistic and been shooting for these numbers in 177? Is it worth tearing down the gun again to see if the current spring will have a good seal on the older setups? I don't know if I have room for it at full length either.
I know this is a lot all at once, sort of thinking this is like a voltage without amps isn't all that dangerous . I guess I am thinking flat top, but really a longer stroke for greater compressed volume is the way to get big gains here I think.
-
Anyone at all?
Either way I have a new plan in the works to get where I want to be. This one will take a little more time than some of my others, but I will keep you updated as there is info available.
-
Hi All:
Mountain Man I just got back in town 15 min ago and I noticed you need the weight for a stock 1377 so here it is.
Weight 32oz (9.91kg). sorry I haven't read all the posts since I left got to play catch up later.
4Th Yote
-
Hey 4th, welcome back .Thanks for the weight, means I have added 6.8 oz so far, not bad all things considered. There is still a little more weight coming before it is all over.
-
Hi All:
Mountain Man caught up on post you are doing some great work. I got a question for you Pg3 you say that you are still getting a loud crack when shooting ----- would two drill holes in the muzzle brake just in front of your barrel quiet it down. I think the air pressure just behind the pellet would vent before exiting the barrel ??? Might help. Last question where did you get the derlin stock and how much is it.
4Th Yote
-
4th Yote Recon Bn.
Love that Name...... :)
-
Thanks 4th yote, I think the difference in noise may be from the front cut on the brake. It is straight across , not beveled at the edge like barrel when I re-crowned it. Holes drilled may help noise wise, but I also would think may have an impact on POI if not done properly.
Does anyone use or make different hammers or do we all just change springs?
Ethan
someone else put this up already but it is a good resource.
http://www.onlinemetals.com/merchant.cfm?id=203&step=2&top_cat=181 (http://www.onlinemetals.com/merchant.cfm?id=203&step=2&top_cat=181)
-
Hi All:
Vet thanks I like my name as well. Now back to business Mountain Man about your hammer would polishing and adding lightening cuts or adding drill holes help take off weight to make your hammer lighter ??
4Th Yote
-
Definately would be lighter, I don't know what material is used for these. Looks like some type of steel maybe. It would have to be fairly hard to smash that chrome pin in the valve without damaging the face of the hammer. Also I think if it were shorter, allowing for longer spring travel might be good too. Not so much a weight reduction, but a longer path and spring to be able to push it harder without maxing out the compression rate. Maybe easier with a longer power adjuster too.
-
Hi All:
Mountain Man you could try a longer power adjuster it might help. I used a 3/8x1/2" set screw and I have it backed out to a full 1/4" with plenty of adjustment left.
4Th Yote
-
I was thinking the adjuster itself and not just the screw, making the overall length of travel greater.
-
Hi All:
Mountain man Mellon air has them for $8.00 w/ no shipping fee you could try that to see if it works better.
4Th Yote
-
His stuff is good , That is what is on the one in my sig. down below. That rifle is shooting superdomes at 625 fps. It has his "18 barrel, valve, and flat top piston too.