Kwc 1911 co2 - How to reduce fps?

[Mad Rag]

Not long got this but it's a little hot for my CQB site , only 10fps over how can I bring this down a touch.

 

[EDcase]

What I would try is to file down the valve pin a bit.

Use a fine file and take your time so as not to damage the seating.

A dremel whould be good for this if done gently.

If it gets messed-up then you'll just have to replace the valve with a low pressure one.

 

[heroshark]

there is an npas for it but seems hard to get hold of. If you crop the floating valve spring in the nozzle you should be able to drop it by that much.

 

[EDcase]

Wouldn't you want a stronger spring to reduce output?

I'm thinking of the return spring...

 

[Mad Rag]

thanks all for this. so i asked a few of the guys at the site and i was told you can drill holes in the barrel to fine tune it or put a restriction kit on it. im not very tech minded

file down the valve pin a bit.

Click to shrink...

 where is the valve pin and how much would need to be taken off?

crop the floating valve spring in the nozzle

Click to shrink...

again not sure on this where is this located. 

thanks again

 

[EDcase]

I wouldn't drill any holes in the barrel myself but it should reduce the power if that's the way you want to go. It may affect BB flight tho.

The pin is the the centre of the valve at the back of the magazine.  Its the bit you can push in when empty.

I'd guess to take off about half a mm but you'll need to chrono quite often to see how its affected.

As for the spring: you'll need to remove the valve with a valve key. (google search)

 

[heroshark]

Wouldn't you want a stronger spring to reduce output?

I'm thinking of the return spring...

Click to shrink...

weaker, closes sooner sending less out the barrel

 

[EDcase]

weaker, closes sooner sending less out the barrel

Click to shrink...

I must be thinking of the wrong thing.  Doesn't the spring push the valve closed?

 

[heroshark]

no holds it open

 

[heroshark]

again not sure on this where is this located. 

thanks again

Click to shrink...

It's in the nozzle in the blow back unit.

 

[EDcase]

Ah, I was talking about the spring in the valve

I haven't tinkered with pistol internals yet.

 

[heroshark]

Ah, I was talking about the spring in the valve

I haven't tinkered with pistol internals yet.

Click to shrink...

Figured you were. That is another way to adjust it though. Having to do it on all mags and equally (unless you had a ready supply of springs you were fitting) would be hard and it would not make a big difference. Tbh cropping the floating valve spring is also minimal difference but dropping 10 fps you may just do it.

 

[EDcase]

Good point about having to modify all mags.

I'd still try modifying the valve itself for these two reasons: 

1. More gas efficient

2. Less stress on other parts to restrict gas flow.

Since it only needs reducing a small amount filing the valve pin would be my first try.

 

[heroshark]

Good point about having to modify all mags.

I'd still try modifying the valve itself for these two reasons: 

1. More gas efficient

2. Less stress on other parts to restrict gas flow.

Click to shrink...

What in?

 

[EDcase]

The mag valve

 

[heroshark]

on what gun I mean?

 

[EDcase]

On MadRag's 1911 but I would do the same with any pistol that needs a little lower fps.

Also depends how many mags would need 'adjusting'

 

[heroshark]

Sorry got befuddled thought you were referring to something you were working on. It's much easier modding something in the gun. For example if you wanted to lessen the actual gas out put filing the face of the valve knocker would be most effective.

 

[EDcase]

Yep, that's a good solution if the fps is consistently high with all mags.

Hard to get to tho?

Would need to do a complete tear-down to get to the hammer and then reassemble to test.

 

[Mad Rag]

a wee update for you, used a different type of co2 bulb and the fps came down quite a bit.