GTA
Airguns by Make and Model => Crosman Airguns => Topic started by: DavidS on September 24, 2014, 10:50:02 PM
-
The Crosman 66 is a good gun in its rifled form (currently sold as 664gt), and it holds a lot of potential beyond what you get out of box.
Many of the power mods are the same as with the Crosman 13xx/2289 guns, though there are a few that belong only to the Crosman 66/760.
To help promote the use and modification of the Crosman 66 I am providing a list of quite effective modifications to improve accuracy, power, and safety. Of all of the current Crosman branded AirRifles the 66 is my favorite (unless you count the 2289 as a rifle) and I do not feel it gets the attention it deserves..
If you are aware of other mods that apply to the Crosman 66 please add them. And I am aware that it is a simple matter to install a flat topped valve and piston, though I am cup headed all the way with the Crosman MSP's :).
Power mods:
- Stuff the piston (with steel rod like people do with the 13xx guns)
- Weaken the valve spring
- Strengthen the hammer spring.
- Carefully bore out the transfer channel to the barrel just a little
- Port the valve in the same way as is done with the 13xx guns
- Shave 4 thousandths of the nose of the valve.
- Shim the pump cup with a washer behind the seating point that is 4 thousandths thick.
- Increase the internal valve volume by drilling into the check surface, and cutting back a couple of threads.
- Insert a one eighth inch diameter piece of steal rod in the front of the check seal of length to mostly fill the intake port.
Accuracy mods:
- Tape the end of the barrel to fit snug (not tight) in the hole in the front sight assembly.
- Recrown the barrel.
- Polish the sear contact points.
- Install a lighter trigger spring.
- Polish the hammer.
Safety mods:
- Remove the bar that blocks the trigger when the bolt is held back (so that you can uncock the gun with out firing).
-
All of this can be put towards the M4-177 as well, and the Recruit (although it's a smooth bore, a 66 barrel is a drop in replacement), and I'm sure the MK-177 even though it has a larger piston/valve diameter.
A note, since the trigger spring is a torsion spring, it's easier to just bend one of the legs a little than find a replacement.
I flat topped my Recruit, pinned the valve (screwing the valve to the tube), made a flat top piston with a pin to go into the intake port, flat topped the valve only leaving .020" on the front of the valve to keep the O ring in and of course put in a rifled barrel. I might have angled the exhaust port but I don't remember... The only spring that is modified at all is the trigger spring. It hits 750fps at 10 pumps, at 15 pumps I get one at 750 and one at 550 (haven't pulled the chrony out again to see at what point I get two at the same)
The 66, M4-177, and Recruit all share the same internals, tube, linkage, valve and piston.
If you can get the same performance out of the pump cups that's cool, I just have the tools to make flat top pistons so that's the direction I go :), I might try a delrin one next time...
-
@rangerfredbob:
Nice results from your Recruit.
I have tried Flat Top setups on my Crosman MSP's and while it does produce better than stock results, I have found that tuning out the cup piston setup produces even better results. My best results have been with a home made adjustable aluminum cup piston, though stuffing the piston gets quite close to the same improvement. And all the tools needed are a Lathe, Drill Press, tap & die set, and Mill, these are tools that I think we all have (except those who are rich enough to by pre-made everything [I am way to poor for that]).
One that I have yet to try is to take some of my steel stock and make a longer rifled barrel. That would likely produce better power, though it is one thing I have yet to attempt.
I have also been debating converting my 66 to .22 cal, and making clips to work with that. I am just not certain that it would be worth the effort of modifying the transfer port, modifying the plastic lead, making a new bolt head, etc. I have a number of projects in progress at this time including 3 AirRifles made completely from raw materials.
-
I have a number of projects in progress at this time including 3 AirRifles made completely from raw materials.
Could you make a new post and take pictures and tell how you built the gun? I am really interested in your homemade gun. ;)
-
I have a number of projects in progress at this time including 3 AirRifles made completely from raw materials.
Could you make a new post and take pictures and tell how you built the gun? I am really interested in your homemade gun. ;)
I will be. At this point they are a work in progress, and a slow one as I am getting everything on the property ready for winter before we get a freeze. I have to cut wood, insulate piping, redo the house and shop insulation, get winter tires on the my vehicles, and a bit more before we get a freeze.
In a few weeks I should have something to show, we will see how well they do.
-
I have a number of projects in progress at this time including 3 AirRifles made completely from raw materials.
Could you make a new post and take pictures and tell how you built the gun? I am really interested in your homemade gun. ;)
I will be. At this point they are a work in progress, and a slow one as I am getting everything on the property ready for winter before we get a freeze. I have to cut wood, insulate piping, redo the house and shop insulation, get winter tires on the my vehicles, and a bit more before we get a freeze.
In a few weeks I should have something to show, we will see how well they do.
Okay ;)
-
@rangerfredbob:
And all the tools needed are a Lathe, Drill Press, tap & die set, and Mill, these are tools that I think we all have (except those who are rich enough to by pre-made everything [I am way to poor for that]).
David, not everyone has the tools and accessories that are needed to use the tools. I don't have the tools you mentioned nor a shop to put them in. Therefore, I have purchased pre-made everything. I too am not a "rich" guy. I can't afford to buy a lathe & all the bits & pieces that are needed to make the same quality parts as I can purchase from the pros.
Just thought I would show an other point of view. ;)
-
@rangerfredbob:
And all the tools needed are a Lathe, Drill Press, tap & die set, and Mill, these are tools that I think we all have (except those who are rich enough to by pre-made everything [I am way to poor for that]).
David, not everyone has the tools and accessories that are needed to use the tools. I don't have the tools you mentioned nor a shop to put them in. Therefore, I have purchased pre-made everything. I too am not a "rich" guy. I can't afford to buy a lathe & all the bits & pieces that are needed to make the same quality parts as I can purchase from the pros.
Just thought I would show an other point of view. ;)
Sounds just like me. ;) While I do have a couple tools I do not have the tools you listed above. And like Bill I do not have the money to buy that kind of stuff. However I love to tinker and make things better. ;D ;)
-
All I use to make flat top pistons is my metal lathe (got off craigslist for $250, 7x12" like the Harbor Freight one), $50 harbor freight drill press, $20 harbor freight tap/die set, hack saw (or the $10 garage sale bench top band saw), and random files. Sure it takes me longer and might not be perfect but it works fine...
If I get time soon I'll try to see what I can get out of the pump cup, I've got a couple guns that could use a little modding... maybe do two of the same gun with the same valve mods one with flat top and one with a pump cup
-
Me I have couple drill presses and a die grinder and a dremmel...
I do have a lathe but it is the wrong kind (wood)...
I do not much like the new 66 as a 66 but it is good for a 13xx powerplant with a stock 13xx valve...
As a 13xx with an extended valve about .2 ci should be possible which would make for a decent .25 or with a power adjuster a decent .22 acp and excellent .177 acp...
-
@rangerfredbob:
And all the tools needed are a Lathe, Drill Press, tap & die set, and Mill, these are tools that I think we all have (except those who are rich enough to by pre-made everything [I am way to poor for that]).
David, not everyone has the tools and accessories that are needed to use the tools. I don't have the tools you mentioned nor a shop to put them in. Therefore, I have purchased pre-made everything. I too am not a "rich" guy. I can't afford to buy a lathe & all the bits & pieces that are needed to make the same quality parts as I can purchase from the pros.
Just thought I would show an other point of view. ;)
Yea it is point of view. For me it was cheaper to buy the tools and spend a total of about $1500.00 over a years time than to spend many thousands on water valves, pumps, engine parts, break parts, mounts, etc, etc over the long run. I can not afford to buy these little things so I make them, and as such when I did have the money at times I spent it on the tools needed to maintain my land, house, water and power systems, sewage system, vehicles, other tools, etc, etc, as well as make all of the parts to replace any damaged parts to all of the above at nearly no cost. The first thing that I made once I got both a lathe and mill is a complete set of replacement parts for both :) . You see normaly I do not have even an extra $20 in a month for such things, and as such it makes since to have the tools (and get them when I did have the money). This is also why my AirGun collection is growing so slowly. I also make my own tool bits for the lathe and carbon case harden them. The skill of using these tools and making tools was taught to me by an old school gun smith, and it is a skill that I cherish as it saves me a lot of money (money is something I do not care for [barter is highly preferable], though small amounts are needed in this society).
Steel costs almost nothing, same for Delrin, a bit more for aluminum though a lot less than parts premade from the material.
For the mods I listed for the 66 though you need only a hand drill, vice, rubber mallet, screwdrivers, and the needed bits.
-
I just remembered another mod I did to my Recruit... I necked down the exhaust valve stem diameter just behind the seal using a file (I chucked it up in my lathe but this could be done just about as easy in a drill), I didn't go to a specific diameter I just went to what looked right...
-
I just remembered another mod I did to my Recruit... I necked down the exhaust valve stem diameter just behind the seal using a file (I chucked it up in my lathe but this could be done just about as easy in a drill), I didn't go to a specific diameter I just went to what looked right...
That is one mod that I have done to all of my Crosman valves as well. It is one that I do not think about often as I do it the day I get a order of parts that includes valves from Crosman. Do to the low prices I do order some things pre-made from Crosman, though just some things (valves, piston assemblies [which I stuff], Grips, bolts, and sometimes barrels), all other things I make, often including barrels.
I had not really thought about it though any Crosman part that does not require a metal to metal (or metal to Delrin/teflon resin) air tight seal could probably be made with out a lathe or mill (though I would still use these tools for the time consumed is less). It would just take a lot longer and a lot more work for many parts.
-
I just remembered another mod I did to my Recruit... I necked down the exhaust valve stem diameter just behind the seal using a file (I chucked it up in my lathe but this could be done just about as easy in a drill), I didn't go to a specific diameter I just went to what looked right...
I use my Dremel and it chucks in the collet just like an other bit because it's the same size.
I set it to the lowest speed and go slow because I have mistakenly over heated a couple of them and melted the head right off the end.
-
I bought a new model 66 (as the 664GT I think) a while back. I mounted a better scope than the cheapo that came with it, though the open sights aren't bad. I am quite amazed at how well mine shoots. The trigger is very possibly the best among my air rifles. Accuracy has been excellant. Very few flyers, and very many tight one hole groups. I have not, and probably won't be, trying BBs. It's got too much plastic, but, here, rust is a problem.
I shoot off a rest at 10 yards mostly, with cheap pellets from Walmart, as nobody sells the premium ones here. Even stock it's a fun and accurate little air rifle.
-
I could not get mine to stay at the same poi it kept shifting at the shroud/breech. It does make a good 13xx powerplant... :D
-
I could not get mine to stay at the same poi it kept shifting at the shroud/breech. It does make a good 13xx powerplant... :D
That is why taping the barrel is important on the shrouded barrel MSP's. Mine is quite accurate (almost as good as my Daisy 880's, though not quite).
I am considering putting a 2100 pump tube, valve, hammer spring, and pump linkage on my 66 as well as making a solid piston for it with a 2100 linkage and tube.
The 2100 must be made for someone quite tall, as the stock is to big for me (the Daisy 901 stock fits me perfect). That and the pellet loading are my two biggest complaints about the 2100, putting the 2100 tube in my 66 would cure both issues :) .
Though I really do need to buy more clips for my 66 (and a couple more 66's plus more 2100 pump tubes & linkages & valves).
-
I am pretty good at tinkering but the shroud ends at the receiver instead of going thru like the 2100 does and the plastic receiver flexed on mine a bit.
Was tempted to put a 7/16 barrel in it but decided it would be a become a 1322 pump. Then found a 760 pump and put that on the 66.
-
It's a shame they took the 66 away. Nice clip and rifled barrel. Adult size out of the box. I installed an o-ring on the bolt from a 1377 awhile back. It fits.
-
Made a trigger shim and epoxied it in. It's in the shape of an L bracket. Took away half the distance on the pull.
-
I might try stuffing the piston or maybe make a metal piston. Now that I have a way to measure.
Stock piston, lighter valve spring and angle port:
626 fps 10 pumps crosman 66
643 fps 11 pumps crosman 66
653 fps 12 pumps crosman 66
-
After experimentation, I can say for sure that stuffing the piston with nails really does work. One thing that didn't work was putting a washer shim behind the cup. That resulted in loss of fps. And another thing that didn't work was putting an O-ring behind the pump cup to work with the shim. It wouldn't even pressurize! I did file the nose of the valve a little to match the pump cup. I'm up for more mods if anyone has real data to back up their claims. Feel free to reply! Anyway, here is my results:
668 fps 10 pumps
685 fps 11 pumps
709 fps 12 pumps
-
I'm not too familiar with the 66, but most similar guns benefit from an extended, smaller diameter bolt probe.
-
Ok. I'll give it a try. I'll push the pellet in further by hand and see if it does anything.
-
Ok. I'll give it a try. I'll push the pellet in further by hand and see if it does anything.
'
ok power mods. i really like the stuffed piston mod.. very cheap.. My mod is rigidity. Where the pin intersects the pump linkage.. Open your pump arm to 90degrees from the gun and have it hanging torward the floor. Now try to wiggle it back and forth (side to side).. if the pivot point has any flex in it, your actually losing some power.. use some small washer and shims to make it so that in the same position there is no play in that linkage.
-
I might have a little. So put a washer in the gap between the linkage?
-
id make it so its dead centered with no slop.. so it may take 1 on each side.it varies soo much in these guns its crazy, I do remember the linkage on my 417 had a lot of play though.yes, it looks like u surely need 1 or more
-
the center washer wont do as much as outside washers for the side to side stability.
-
Ok. I'll keep that in mind. I just have a drill bit shank in the pivot so I can quick release. By the way, I did a quick test with the pellets pushed in further by hand. I guess I'll be working on an extended bolt probe soon! Thanks 2K1TJ for the idea.
10 pumps 683 fps
11 pumps 694 fps
12 pumps 714 fps
-
Shimming the pivot side to side does nothing for power that would be anywhere near measurable...
On my Recruit that is the same as a 66 with a different stock I flat topped the valve and made a piston, pinned the valve to the tube, put a wire in the piston face to take up volume in the intake port, ported the exhaust port, contoured the valve and stem. With that setup I get 750fps on 10 pumps with crosman pointed pellets and one shot at 750 and one at 550 at 15 pumps. Unfortunately the valve leaks and I broke off the screw that I used to pin the valve. .. I need to order a couple more 66 barrels if they're still available since I have another recruit to build up, they aren't rifled stock
-
I also have a theory on thy the washer and o ring under the pump cup didn't work for you, doing that made it so the pump cup is either covering the pump slot not letting air in or it is warping the pump cup to the point it is not sealing in the tube, those mods can be picky that way
-
Ok. I might try sanding the sides of the O-ring and sand the washer down some more. Maybe it will seal better. I was thinking of filling the inlet on the valve with wire. I've seen the pictures of people drilling into the check valve and I assume they glue the wire into it. Not sure how much restriction that creates when pumping though.
-
Ok, I got the o-ring and washer to work after reducing the width. It pressurized. A little more speed. I didn't push the pellets forward though.
10 pumps 688 fps
12 pumps 724 fps
-
My thoughts FWIW.
The extended and reduced probe bolt should also unshroud the barrel port allowing more air to flow for you. Pushing the pellets farther into the lead is helping with your existing setup if the skirts are hanging over the barrel port a bit. The extended and reduced probe accomplishes both, but results will vary with pellet skirt design and probe design. For example, If you have an extended probe with a very small diameter ( for increased flow ) and use it with a deep skirted pellet, the benefits are marginalized. Crosman pellets like the CPHP or Magnum Domes would be my choice since they have shallower skirts with a flat inside. A pellet like an RWS Super Dome might not work as well since they lack this flat and the narrower probe may enter the pellet deeper before finally bottoming out and pushing the pellet into the barrel. This could leave part of the skirt hanging over the barrel port which is bad unkay?
Simply browsing on eBay for a few minutes looking at "Crosman bolt" will show you the variety of products out there and give you some ideas.
-
Thanks for the advice. I've been using the crosman pointed hunting pellet 7.4g . I was looking at the designs of bolt probes. Pretty interesting. It looks like I could make mine about 3/8" long. Looks like people just use music wire.
-
Thanks for the advice. I've been using the crosman pointed hunting pellet 7.4g . I was looking at the designs of bolt probes. Pretty interesting. It looks like I could make mine about 3/8" long. Looks like people just use music wire.
I only have a couple .177 guns and don't shoot them often but in almost every case, I get better groups with domes VS pointed regardless of caliber ( .177 VS .22 ). That said, the Crosman "pointed" hunting pellets are more of a rounded dome anyway, sort of like the H&N Baracuda.
FWIW I modified a MK177 and made a probe style bolt for it as well as stuffed the piston and ported the valve. I gained FPS and dumped more pumps but POI would shift out of the blue with groups suddenly forming low left, then back to original sight point. I gave up playing with it but it is similar in internal construction and powerplant to the 66 you're modding. I like the clips for loading in particular.
-
http://www.crosman-air-pistol-owners-forum.com/board/index.php/topic,13807.0.html (http://www.crosman-air-pistol-owners-forum.com/board/index.php/topic,13807.0.html)
(http://www.gatewaytoairguns.org/GTA/index.php?action=dlattach;topic=64968.0;attach=80519)
(http://www.gatewaytoairguns.org/GTA/index.php?action=dlattach;topic=64968.0;attach=80605)
-
Excellent K.O.! I remember reading this before but couldn't find it again. I'm interested in the 1/16" brass tubing for the valve inlet. It would be an easy mod. I'll check the K&S rack. I don't think I'll be doing the barrel porting. The rubber gasket sleeve diameter is matched for the stock set-up. Might be risky thinning the plastic.
-
Shimming the pump cup works just not David's way it will want what it wants not a fixxed amount... it helps at higher pumps by pre-compressing the rubber cup just like 1300-1500 psi would at 15+ pumps... only pumping ten times about 1000psi ...well then you only need it to pre-compress a bit... the point is like sleeving the intake the purpose is to reduce headspace...
pretty soon I will be tearing it down and converting to a 19" Crosman .177 barrel. may do a bit more fine tuning (like a valve that is not ported for .22)... in .177 smaller porting help keep velocity high...
Hoping for about 800+fps with 7.9g CPHP...
was thinking of using my 19" L.W. barrel or 20.6" Daisy 953 barrel but I decide to sleeve them for my .25 Mrod test mule... may even pick up and sleeve a 26" Maximus barrel for it...
-
oh yep ya need to pin the valve to keep the valve from moving back as the little punch pressed catch ledge gouges its path...front trigger frame screw needs the help imo...
-
I have a question about the plastic barrel breech on the 66. Can that be removed or replaced with a new one if it breaks? Seems like it's on there pretty good. How did they attach it? Also, can the aluminum barrel breech on the 2100 be modded/hacked to fit the 66 receiver?
-
I have a question about the plastic barrel breech on the 66. Can that be removed or replaced with a new one if it breaks? Seems like it's on there pretty good. How did they attach it? Also, can the aluminum barrel breech on the 2100 be modded/hacked to fit the 66 receiver?
I would take a look at the Crosman EVP PDF on the 66 for the parts. Chances are good Crosman sells the parts and they are probably very affordable. Haven't looked into it myself to say for certain but that's where I would start.
Here's the link off the Crosman site for the 2008 to present model 66.
https://support.crosman.com/hc/en-us/article_attachments/201591940/664SB_664GTW_EVP___PL.pdf (https://support.crosman.com/hc/en-us/article_attachments/201591940/664SB_664GTW_EVP___PL.pdf)
-
That little plastic transfer port thing is $1.15 and is just a press fit onto the end of the barrel. it's not hard to remove as I replaced my barrel with a rifled one and reused the stock plastic piece. I took it off by holding the barrel against a wood shelf vertically that has a sharp corner at the top, I slid it against the corner a few times softly, turning it 180* every time to push it off evenly. The end of the barrel is knurled which is why it is hard to get off.
-
Ok. I get it. I didn't know it was sold separately from the barrel. Thanks.
I did the extended bolt probe! Now to reassemble and try it. Used a 7/64" drill bit. It fits perfectly. I tapered it down once it cleared.
-
Wow! That was really worth doing! 8)
10 pumps 704 fps
12 pumps 735 fps
I have the brass tubing to put in the valve inlet. That's next.
-
I had to mod the clip. I didn't account for spring back when cocking the hammer. Works great!
-
653 to 735 fps all on mods sub 5 bux , incredible :D
-
653 to 735 fps all on mods sub 5 bux , incredible :D
This stuff gets addicting!
I had the larger check valve lying around. I put it in and it was slower. -10 fps. Took it back out, then
put the 1/16" valve inlet brass tubing in. Not enough change to tell if it did anything. I noticed the barrel has a small leak at the plastic part. I glued that up. Just waiting for it to dry.
-
good call.. have u pinned the valve yet?(or waiting to possibly do more valvework) another idea ive seen is stuffing the valve , this works in some cases and others it doesnt. Your basically lowering valve volume to achieve higher pressure
-
No, I didn't pin the valve. It has a lot of preload from that shim under the pump cup. It might be ok. It would of broke by now if it wasn't. I thought the bigger check valve was stuffing the valve? It didn't like it.
-
hmm. a bigger delrin check seal stem internally? internal added mass is stuffing, adding volume is the opposite.. i probably missed that part.the pinning is a great mod on the 2100, after looking it wont do much in the 66
-
Well it's easy to pin the valve and one advantage is it keeps the valve from deflecting under pressure. I wouldn' worry so much about the screw failing but at higher pumps it might start to tilt somewhat. A 90 duro o-ring on it would help too but pinning it would be a safer move.
This 66 mod thread fun to follow but I'm working similar mods on my newly acquired 1377 next. All I've done so far is trigger mods for smoother, lighter pull Not going to hijack - starting my own thread.
-
Dave, just replied to your PM.
With that longer check valve you put in, did you put in the spring that would have went with it? if not, that's why you lost speed because there is more preload on the exhaust valve meaning it probably retained more air than you were before...
-
I got the message. I'll try some of those things to keep my bolt from blowing back. Thanks.
When I used the longer check valve, instead of using the spring that goes with it, I cut a new one the same length that was lighter.
-
I guess I'm done modding the 66. I put in a new o-ring with the pump cup which sealed fine this time. Shimmed up the hammerspring a bit, used a piece of rubber to shim the bolt from blowing back. It still blew back though on 12 pumps. The plastic bolt is small diameter and just isn't designed for high power. So I stop pumping at 10 pumps as there are no problems. By the way, I was wearing my safety glasses.
It delivered 726 fps on 10 pumps!!!
-
One thing I noticed is that the bolt isn't held down by the hammerspring when firing. It just relies on the tiny plastic indent.
-
Does the bolt on a 66 have an o-ring? May try adding one if it doesnt.
-
Does the bolt on a 66 have an o-ring? May try adding one if it doesnt.
Yes, I put an o-ring on there from the 1377. I just barely grooved the drill bit to get the diameter right.
I think it works pretty good the way it was blowing back. The trigger blew back too stronger then you can hold. :o
The rubber spacer is worth doing. It's just a piece of fuel line. It makes the action better. Takes the play out too. I'm not sure if the pellet depth is right though. I think it gets pushed into the barrel. Is that ok? By the way, last reading at 12 pumps was 748 fps. It had some air not dumped though.
-
Does the bolt on a 66 have an o-ring? May try adding one if it doesnt.
Yes, I put an o-ring on there from the 1377. I just barely grooved the drill bit to get the diameter right.
I think it works pretty good the way it was blowing back. The trigger blew back too stronger then you can hold. :o
The rubber spacer is worth doing. It's just a piece of fuel line. It makes the action better. Takes the play out too. I'm not sure if the pellet depth is right though. I think it gets pushed into the barrel. Is that ok? By the way, last reading at 12 pumps was 748 fps. It had some air not dumped though.
Exact same problem I had on the MK177. After shooting it a lot for a few months, the catch on the clamshell housing that holds the bolt in the breach while firing was worn out and the bolt would get blown back. That spring action from the bolt was done too. I put rubber under it just like you. That helps but it still gets blown back when firing. The parts are fairly cheap but still...
-
I saw a guy use a 760 bolt in a 2100 crosman. It must be the same mechanics. Does the hammerspring engage the bolt at the end on the 2100? Or does it leave a gap like the 66? I see people getting 800-900fps on those. What's the difference? Maybe they left a gap because of the clip.
-
Cut back my bolt probe. Pellets are not being pushed into the barrel anymore. It's the correct length now.
-
Latest reading- 733 fps on 10 pumps 7.4g
-
dave , have u exhausted all options ? flat top and pinning the valve etc?
-
I haven't exhausted everything. There's always more options out there. I replaced the o-ring again. The plastic piston has slots which make indents into the o-ring. After awhile, the o-ring somehow causes a leak. I think a flat top piston would be great or maybe make a longer piston to get rid of the o-ring and washer under the pump cup.
-
yep, flat topping would bypass those issues .. probably gain u 100 fps too , especially of accompanied by pinning..I also stand by my claim that tightening up the pivot point yeilds gains, ive proven it so people sayin it wont have never tried..
-
Another thing on the older guns that gets really good gains is stuffing the piston with nails and Jb weld ( in the 4 slots because apparently theres a lot of flex in the plastic)
-
http://www.network54.com/Forum/275684/message/1166912292/Here%27s+something+else+you+can+do+with+drill+rod-+Stuffing+the+stock+1377+piston+rod (http://www.network54.com/Forum/275684/message/1166912292/Here%27s+something+else+you+can+do+with+drill+rod-+Stuffing+the+stock+1377+piston+rod)
-
I did the nail stuffing awhile back. There's a picture of it in here somewhere. Whats impressive is how much the little washer and o-ring under the pump cup does. I took them out today and took a loss of 60 fps. So length is key.
-
okay.. try tightening the pump pivot , it cant hurt thats for sure.. the piston would need to be adjustable to be dialed in for the proper stroke.. seeing as how the valve would also be flat topped leaving a 1/4inch gap from stock lenght./. really simple id suspect , but since no one is mass producing em for the 2100 model series its not like specs are floating around.. i know the valve and piston are slightly different than lets say a 760
-
i gotta go back in ur post and see what the piston looks like
-
I found a picture with the oring on it. I don't think too many people are doing this trick anymore. They just buy an adjustable one. Since the bolt blows back at 750fps, why bother. ::)
-
I found a picture with the oring on it. I don't think too many people are doing this trick anymore. They just buy an adjustable one. Since the bolt blows back at 750fps, why bother. ::)
Yep!
Reached the limit of the design parameters for the gun I'd say.
All considered though, it does shoot harder and is more accurate than stock right?
Similar mods to one of my MK-177 and it shoots a lot harder than the stock one. It's louder too, which makes sense.
My boys and I were shooting them a few weeks ago having a blast and you could really tell.
I had the probe tip too long at first too, and could not load pellets initially.
-
In stock form, the 66 shoots around 625 fps so going to 733 fps is a nice improvement.
-
theres gotta be a mod to stop the bolt blow back , this happens on my co2 crosman m4-177 also, the thing is shooting hot ( like 700 +) I would think a small 6-32 grub screw on the exposed part of the bolt.. the friction along the bolt housing would stop this instantly..
-
So basically behind the finger tab ( cocking knob) a grub screw goes into the traveling bolt that rides along the frame. it either directly runs the side cover ( barely ) or has a small oring on it which does the same.. This will allow the user to percieve almost no additional force , yet arrest the bolt in the forward postion
-
hi all,
i've been following this thread & finally got something......
for...dave----(Cut back my bolt probe. Pellets are not being pushed into the barrel anymore. It's the correct length now. )....
..i have a 760 that has the same receiver as the 66 and had that same problem a while back. to fix....
1)with a soldering iron, i made the slot for the bolt a 3\16" longer at the back end of the slot. 2)with a soldering iron, i melted off the back end of the bolt so it could go back & use the longer slot. 3) again with a soldering iron, i increases the slot on the bottom of the bolt that pulls on the striker cocking pin.
these 3 mods allows the probe to be longer & still pulls back enough to properly load the pellets.
after doing this most of my pellets loads into the barrel past the transfer port. the one i use the most the crosman pointed hunting 7.4g still did not. so i made a flow thru bolt. here's a link to a post i made..
...http://www.gatewaytoairguns.org/GTA/index.php?topic=48761.msg460291#msg460291 (http://www.gatewaytoairguns.org/GTA/index.php?topic=48761.msg460291#msg460291)
as for the bolt blowing back.... i did some mods for it too. see my reply in the thread http://www.gatewaytoairguns.org/GTA/index.php?topic=113637.msg1090795#new (http://www.gatewaytoairguns.org/GTA/index.php?topic=113637.msg1090795#new)
plinker
-
Thanks plinker99. Nice mods. I was thinking of filling the slot on the bottom of the bolt to get rid of the gap. But, somehow I don't trust this design for high power. Too much plastic and not beefy enough. Needs more metal parts. I do like the gun though.
-
thats what i like about the 880, the steel chassis.. Is the clamshell flexing on your gun at pump 10 and up?
-
I pump it with the stock on my thigh so that there's no excessive force on the receiver. There's only 1 bolt holding the stock. Another weak spot. I don't know why they made the transfer port barrel thing plastic. I can see that splitting if overpowered. I also don't care for the bolt which is too small in diameter. I've read of people actually sleeving it with metal tubing to increase strength. Don't know if that would work with a clip. Funny thing is they use the same diameter bolt on the 2100. The 880 has a beefy bolt compared to the crosman's.
-
yep,,, i noticed a bunch of little issues like that on my crosman m4-177 co2 conversion, just soo many weak points , and the bolt blows back hard now that its shooting faster than stock
-
I've heard about some Crosman, yes, AND Daisy multi-pumps breaking the stock when pumping. Since I'm such a cheapskate that I want all my airguns to last forever, I came up with a method to pump them and put no stress on the stocks.
While sitting, I rest the end of the butt stock on my right leg with the rifle pointing up in the air. Then I open the pumping lever all the open, and briefly pause. Then, I put my right hand onto the top area of the gun just opposite of where my left hand will come to rest when I close the pumping arm, and support the gun while completing each pump, so my hands kind of come together.
I keep seeing youtube videos of shooters holding the rear stock with their right hand, and pumping that thing so fast and hard you'd think it was an Olympic event. I never do that. If I'm in such a big hurry to get the next shot off, then I probably should be using a break barrel, PCP, or CO2 repeater.
Yes, I even want my 760B to last forever.
-
Tagged
-
Hi Aaron and welcome to the GTA....
I know you're new here but you might want to check the date on the thread you are looking at. For example.. this one hasn't had any activity since 2016. You can still find useful information in many older threads but likely won't find anything new.