lowering fps on a co2 pistol

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kasaran

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some buddies i go shooting with said this is a thing.  though i have never heard of it as an option as its not just a matter of adjusting a spring.  does anyone know how this is done, or who can do it for me?

i brought the kwc luger and on a fresh co2 cartridge it fires at around 380 fps.  after emptying the magazine (15 bbs) it then drops to within legal limits. 

currently clutching to straws that they will let me use it if i make sure to fire off a few before taking it out into a game.

 
In ni we're limited to 328 and the most common way i see manufacturer modded guns do it is to have a hole drilled in the nozzle.

Wouldnt reccommend it though, throws your accuracy to the wind.

A side option, depending on how the valve works, is to put a small o ring or washer behing it, tried that on my we sig and it dropped the long barrel fps from 380 on .3's to 320 on .2's

 
I have a KWC G17c... hot out the box at 390-400 fps. 

Had a mod where an O ring was added to reduce Co2 capacity in the spring chamber inside the slide (sorry my technical  but it didn't last so Luke at the Mall did a better mod. I believe he used a tooth from an old aeg motor, bloody genius and £30 you cant go wrong. 

Ah yes... as Adolf correctly pointed out, placing the O ring behind the valve but don't use superglue as the rubber will perish and it will just climb back to illegal fps limits. This is why Luke used a cog tooth that was inserted and glued into place.

 
Duff said:
I have a KWC G17c... hot out the box at 390-400 fps. 

Had a mod where an O ring was added to reduce Co2 capacity in the spring chamber inside the slide (sorry my technical  but it didn't last so Luke at the Mall did a better mod. I believe he used a tooth from an old aeg motor, bloody genius and £30 you cant go wrong. 

Ah yes... as Adolf correctly pointed out, placing the O ring behind the valve but don't use superglue as the rubber will perish and it will just climb back to illegal fps limits. This is why Luke used a cog tooth that was inserted and glued into place.
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so litterally glueing an object in the chamber to reduce its capacity?

 
kasaran said:
so litterally glueing an object in the chamber to reduce its capacity?
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As I understand it yes it's that simple. Lowering the capacity of the chamber area. When I had the ring fitted it was firing at 340, then after a few mags it went up to 360 and eventually was back up to 394. Opened it up and the O ring was perished to fuck, hence why Luke used a motor cog inserted into a hole he machined in by hand. He charges £30 an hour and he fixed mine in 10 minutes, that still earned him a score in my book.

Solid at 294 now.

 
Duff said:
As I understand it yes it's that simple. Lowering the capacity of the chamber area. When I had the ring fitted it was firing at 340, then after a few mags it went up to 360 and eventually was back up to 394. Opened it up and the O ring was perished to fuck, hence why Luke used a motor cog inserted into a hole he machined in by hand. He charges £30 an hour and he fixed mine in 10 minutes, that still earned him a score in my book.

Solid at 294 now.
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hmm, may have to look him up. not been to the mall either

 
You could also use a widebore barrel to lower FPS without having to modify nozzles and all that malarkey

 
If it's anything like the guns I've done there will be a spring in the grip usually near the back that controls the hammer you can trim to reduce the fps. Try removing grips and see if you can see one. Then it's just a matter of cutting it down and stretching it to the right length

 
ryo said:
If it's anything like the guns I've done there will be a spring in the grip usually near the back that controls the hammer you can trim to reduce the fps. Try removing grips and see if you can see one. Then it's just a matter of cutting it down and stretching it to the right length
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there is one there, being a luger im assuming its put together different? i think im definately going to have to go to a teckie and ask about this

 
having taken it appart, it looks like the best option would be to put something into the chamber, or maybe put a wider/shorter barrel into it.  i read that weakening the spring in the grip may also foul the blowback as it would weaken everything.  i'll take a small hit on accuracy for a still functioning but legal fps pistol

 
I caved and bought one of these, it arrived yesterday clocking at 390fps. looking at the blueprints it has the floating valve thing, but I can't find a way to get to it, the cylinder assembly looks a mess of springs and pins that I imagine is not gonna be easy to re-assemble, but i'll have a go tonight!

 
So I opened up the cylinder assembly, completely, there's one hairy bit re-assembling where a spring that has to hook onto a pin down the bottom of a blind hole, which I eventually managed with some  long pointy tweezers, I don't think I'd recommend it though! I extracted the floating valve, took some measurements and re-assembled to check i could, and it still worked, So now i'm going to design and print a custom valve pin - bulking it out a bit to restrict the flow, and see how that goes! prolly a weekend project

 
CiderPunk said:
So I opened up the cylinder assembly, completely, there's one hairy bit re-assembling where a spring that has to hook onto a pin down the bottom of a blind hole, which I eventually managed with some  long pointy tweezers, I don't think I'd recommend it though! I extracted the floating valve, took some measurements and re-assembled to check i could, and it still worked, So now i'm going to design and print a custom valve pin - bulking it out a bit to restrict the flow, and see how that goes! prolly a weekend project
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Good stuff mate. Wish you were around when I bought my KWC off a forum member who neglected to inform of its very hot fps.

 
Quite pleased with that!

T4wcsFfU7VdzxAQpmDU1UMKoJ-Jha_bbVu4b1Kq5jLuqrsQMFXX3vKmRxuCH3uuTA5nKSY2XqTpZlOUDtehWrfR9CNdRonkVzd4AA3ShrRj66IdgX2nWP1m1KMDiErQEoBR-H_oFk9H_0kMGZ8um3ti649B3KlB9K_he-cDp7daCxf-MF2n7rhgrmVZqEDMmwqvTdQghErP9m4ix0vE7O_zYz9gvjsSPmL9sr2-G4WPL1g7q3g_-IAsbrDUW7R11kGIi79a2yAgU1PxpA_u3vX2dLgj8jCQB6QXDboDn-nl--PnGh2AoA2Zh-QRRAKnrQqMX5jN_2wiqDEToAs1esAXQuFip7QZigJCn2OkF9j7Fml9tW8Z0gyEMSfTdMzlMcmBH3vIMpb56skNkAUmw0JqG3YhXwHIMPGsC_hl45SGFKbbrMzZufulA7nYGVCa1E9iFGMMVj-KJW4de2ZcNuy-XPljgj79Rkn6eakz0jzkjGiAo36ygzPQIWXnTb5KCw89W23Ibh0WiMACqtyzc-SOtGocqynV7yNPbBGg9Tz2C_RB7gK8Yh1Y814Bu6SPI33-__h6TQ33HaXT5k6Kxwo5MxRsfutWvGLnJ9F4=w851-h1134-no


https://www.thingiverse.com/thing:2970912

 
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