12 FPE roided out 1377!

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Pale_Rider

Pale_Rider

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Feb 16, 2019
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12.63 fpe to be exact lol 

9.3 gr RWS supermag @ 782 FPS with 20 pumps

7.4 gr crosman pointed @ 716 with 10 pumps

@ 849 with 20 pumps

I came upon an article here where a few guys had $400+ into this pistol and were only able to achieve minimal increases in velocity. That just ain’t right so I figured I’d share my results to let people know that this is a worthy project that can turn into a great survival tool. 

So far I have bought:

18 in barrel $30 (baker Airguns)

aluminum breech $36 (baker Airguns)

boss transfer port $11 (AlchemyAirWerks)

adjustable flat top piston $35 (mac 1 Airguns)

power adjuster $35 (alchemy airwerks) *mellonair sells one for $10

flat top valve $free (stock valve cut flat, exhaust port angled for better airflow)

Total= $147 invested 

The most important part here is the adjustable flat top piston from Mac 1 Airguns. They use urethane o rings and a plastic pump head that compresses more air into the valve. All other parts don’t really matter which company you buy them from. Oh yeah ... don’t forget to smooth out your inner tube that holds the piston and valve. There are sharp edges and burrs inside that can cut o rings rendering them less effective. And remember to oil your piston every 100 shots or less if you wanna play it safe



Cheers,

LegionAir


 
I had trouble with the flat top piston blowing O-rings, but I see you found "urethane" O-rings.

I'd love to know how well they hold up. I went back to original valve and piston because I felt that I couldn't trust the flat top system. I've since learned that I can kill small game just fine at 475-500 fps with .22 14.3gr pellets out to 40 yards...providing that I guess the range correctly. If my guess is more than 3 long steps wrong then I may be chasing and stomping though.

🙄
 
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.............and in .177 cal ??? impressive.... i never thought to look at mac 1 airguns for the roided 13xx pistol parts... i had never hot-rodded a 1322.... i used all mellon parts , but seems i could have done better in that area where air is smashed into 760 valve - but with a 14" barrel mine gets close to 600 with 13 pumps if i remember right - i suspect that after one gets that air compression area good under higher pressures , they can pump the 20x.... mine didnt get but 20 fps more after going to 15 pumps - and i backed off and gave it up.... we got the breech seal and transfser port area WAY locked down ... fishinwrencher got about the same i did with stock parts....prolly plastic breech, too, huh ?? - paul.
 
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I grew up hunting squirrels with a an American Classic that shot about those numbers. It works, but you have to place that pellet precisely.

If you are going to use the enlarged plenum valve and the flat top piston with a longer barrel, why not use a 2100 pump tube with the increased stroke to fill it? 

How fast can you get a .22 Backpacker with a flat top piston and the factory length barrel?


 
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I had trouble with the flat top piston blowing O-rings, but I see you found "urethane" O-rings.

I'd love to know how well they hold up. I went back to original valve and piston because I felt that I couldn't trust the flat top system. I've since learned that I can kill small game just fine at 475-500 fps with .22 14.3gr pellets out to 40 yards...providing that I guess the range correctly. If my guess is more than 3 long steps wrong then I may be chasing and stomping though.

1f644.svg
Click to expand...

So far the urethane has held up for a few hundred shots I’ll keep you updated as it gets to the 1000s. Also forgot to mention, the Mac 1 piston has a felt o ring to even apply oil and absorb excess oil in case you over oiled. 

You’re absolutely right about accuracy. The only reason I like more power is less pellet drop for longer range shots


 
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.............and in .177 cal ??? impressive.... i never thought to look at mac 1 airguns for the roided 13xx pistol parts... i had never hot-rodded a 1322.... i used all mellon parts , but seems i could have done better in that area where air is smashed into 760 valve - but with a 14" barrel mine gets close to 600 with 13 pumps if i remember right - i suspect that after one gets that air compression area good under higher pressures , they can pump the 20x.... mine didnt get but 20 fps more after going to 15 pumps - and i backed off and gave it up.... we got the breech seal and transfser port area WAY locked down ... fishinwrencher got about the same i did with stock parts....prolly plastic breech, too, huh ?? - paul.
Click to expand...

Yes the Mac 1 piston makes a huge difference! Adjustable, felt wiper and urethane o ring set it apart from other pistons. I would suggest installing a urethane o ring onto your Mellon piston and installing a make shift felt ring(dremel accessory Home Depot)in between the adjustable piston rod. Should work the same as the Mac 1 piston. 
 
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I grew up hunting squirrels with a an American Classic that shot about those numbers. It works, but you have to place that pellet precisely.

If you are going to use the enlarged plenum valve and the flat top piston with a longer barrel, why not use a 2100 pump tube with the increased stroke to fill it? 

How fast can you get a .22 Backpacker with a flat top piston and the factory length barrel?

Click to expand...

American classic as in crosman 13XX American classic? Wow! That’s one hot rodded factory pistol. From what I remember reading the older American classics only shot to about 500 FPS🤷‍♂️ I could be mistaken. 

No enlarged plenum here the only enlarging I did was angling the valve throat. And using a 2100 tube should work but will require heavy modifying. 

Never tried a .22 backpacker pistol but I will eventually get a .22 barrel it just won’t be stock
 
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Backpacker is 14 inches I think.

Apologies. The 2100 American Classic is what i was referring to. Not the 1377. I called it the 2100, and the American Classic. Same gun.

We used to use the lathe and hog out the inside of the valve, cut down the spring follower/seal and in general increase the valve volume as much as we could. Especially if we were going to use the old 2260 barrels. That is one of the reasons I wanted a gauge to see the actual pressures involved.

I got diverted into recreating a 112 type pistol, and actually got an ugly model finished. Even with a power adjuster, I never did get it to stop burping. Along the way I discovered I am not a machinist and i require better quality parts than I can make in the garage.

I keep waiting for someone to make a shroud that goes over the Bandit air cylinder and covers the barrel. That would get rid of the length problem caused by the factory pickle, give you huge shroud volume and protect the barrel for holster carry. Contour it like the Desert Eagle. Made of anodized aluminum, the weight would be acceptable.




















 
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