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ItsAJ

CO2 Blowback reduction

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Hi I just joined a new site and the limit is 1j my pistol is a Cybergun Colt 1911 A1 the 100th anniversary version, full metal etc, it kicks like a beast and is just awesome, I love it as it is but to really get the most out of it I would to use it on the field.

The pistol shoots at 358fps with 0.20g bbs, now I have no experience of reducing power so I don't know if this matters or not but as I know the gun has two springs as when they made them the blowback was so strong them needed another.

Anybody know how I could lose 30 or 40 fps? Also what way will this effect the blowback?

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AFAIK the only way is to reduce FPS for a C02 or gas gun is to drill the valve or something.

I was looking at getting the KWC Mini Uzi but it shoots 360+ and drilling is the only way other then managing to find a specific Mini Uzi non-export version valve that reduces the FPS.

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That sounds horrible lol, can't imagine doing that to a perfect gun! I wonder then if doing that would affect the hopup system

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I know absolute jack squat diddley but was wondering about a warm CO2 pistol I got....

 

Shoots 400fps - way too hot, and probably each cart lasts say 100 rounds max

Looking around some lame CO2's seem to last much much longer before needing to change carts

 

So was thinking..... ouch.....

 

If there was a way to reduce the stroke or burst or duration the valve is opened

shorter burst length in m/secs = less power/fps and cart "should" last a bit longer

 

I again refer to my opening line I know FA in effect - even less on pistols

but perhaps one day, I may investigate a way to reduce the travel or something

that hammer strikes the valve pin thingy - getting technical here

eg: rough figure of say 15 m/sec burst to 10m/sec burst and slightly less power/fps

 

Like I say I know FA - in fact the one I do know a lot about is absolutely nothing !!!

 

But there has got to be a way of just slightly reducing ooommmmpppphhhhh on CO2

if I could somehow get it to 320/330 and perhaps squeeze a bit more say 20% more

rounds before changing cart, then I would be over the moon

Ahh well - another "project" to look into one day maybe but lmk if anyone has ideas

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AFAIK the only way is to reduce FPS for a C02 or gas gun is to drill the valve or something.

I was looking at getting the KWC Mini Uzi but it shoots 360+ and drilling is the only way other then managing to find a specific Mini Uzi non-export version valve that reduces the FPS.

Yeah I put a thread in about that a few months back, but since found a slightly simpler method but it still requires work on the valve. I believe Rock Climbey Dave on this forum may be able to sort you a pre downgraded Mini Uzi- they are fantastic fun, and G & P now do a sexy metal receiver for them too!

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I will have to take a look a look for this thread, want my 1911 as my side arm :)

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Basically you need you prevent some gas getting to the BB, but not the blowback so just reducing the amount of gas at the mag valve isn't recommended.

 

So you need to dismantle the blowback unit, inside is a plastic pin valve with a spring. The front of this valve is a 3 or 4 sided section which looks like a + or Y when viewed from front. This allows gas to channel toward the hop unit. Basically you need to bulk this area up a bit to cut back the flow of gas. I used small sections of plastic glued to the valve channels with solvent Plastiweld. When cured I sanded it to more of a rounded profile so it would still move freely in the blowback chamber. There was a fairly similar step by step article in AI mag a few months back where they made a new valve for a GBB MP9 but the idea is the same in principle.

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Have a google around and see if there are low flow valves available for the mag, they'd reduce the power.

There might be other brand valves that will work or something, otherwise straffham's idea sounds pretty solid.

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An alternative that may work is to reduce the power of the spring on the hammer. This will simultaneously reduce how hard it hits the gas release valve (so less gas comes out per shot and therefore lower fps) and will reduce the force needed for the blowback. How easy this is to achieve on your gun I have no idea.

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An alternative that may work is to reduce the power of the spring on the hammer. This will simultaneously reduce how hard it hits the gas release valve (so less gas comes out per shot and therefore lower fps) and will reduce the force needed for the blowback. How easy this is to achieve on your gun I have no idea.[/quote.

I wouldn't mess with the spring , it would prob result in not blowing back properly, it's the Valve that needs sorting to work properly. Not esp difficult but does need care.

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Just thought I would give an update on this incase anyone is in a similar situation, I went to gearofwar in Newtownabbey Northern Ireland and they said for £15 they could reduce my 1911 down to 328fps, without affecting hopup, accuracy and the blowback! He said about something being put in the barrel I think, it was a brief convo but I will give it a shot for the price, maybe will get some more details for you guys too :)

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Well yesterday I did a little "tweaking" or grind/file away a bit....

 

I can afford to do this as it was a cheap $hitty CO2, and if I balls it

then I got spares & extra mag for the other same CO2 pistol

 

Looks a little rough but she is firing now at 330 - 340fps

I cut, and filed down a round groove in the hammer

there is now a semi circle groove aprox 2.5mm deep

1mm deep seemed to do nothing 425+

2mm deep started to drop a little - 385

2.5mm gets me to 340 ish - seen 355 once but most is 325 to 345

 

the pin/valve is not getting pushed so far in and so is not releasing so much burst

 

Will take some pics to show what I mean - but it is a BODGE FFS

 

Could of tried washers around valve but had trouble holding these in place

got the hump and thought - wtf lets grind the 8itch and finish with a small

circular/round file - like a half pipe guttering channel but is in line with pin

 

I do NOT suggest anybody does this on a nice decent pistol

 

This was a cheapo nasty £30 CO2 pistol (actually £27 delivered)

If I killed it by taking too much off and left with 100fps - $hit happens

at least I get a spare mag etc for other pistol

 

I strongly do not say this is a good way to do it

but now at least I should be able to use it as a backup/secondary

 

once it starts to drop a tiny bit - there is a very small margin

reckon it was about 0.5mm once she started to lose a tiny bit

so with that in mind you have gotta go very very carefully

 

As long as she stays about 300 - that will do me

still got other one - so will be intertesting to see

new mag & co2 cart in both - how many shots etc....

 

hoping to stay above 300-320fps and mag maybe 150 would be nice

 

 

 

OK - bit of an update......

 

fitted brand new ASG co2 cart and started testing this morning.....

got up to about 90 shots - mag holds 19 plus the odd dry fire when empty

it was early (6:30am and neighbours seemed to be getting pi$$ed)

so left it at 90 shots.....

 

Recently dry fired the rest inside up to about 200 shot mark

then chrono a few bb's @ 260

back inside & dry fired up to 250 shots & she was at 90fps

275/280 & she was out of gas

 

So yeah looks like it might have sort of done what I needed it to:

 

320fps & mag good for 150 maybe 180 bb's - that is getting on for 8 or 9 mags

think I will forget looking for a cyma electric pistol, see how this works out in a month or two

might do the other one but will wait a little while first

think next time I reckon using a small square file to get a nice recessed flat area striking the valve

the round one might look neat or even a bit realistic but smooth square flat surface to me might

provide a more accurate consistent strike on valve than maybe the round halfpipe shape

 

pistol - alas out of stock now :(

 

http://www.onlybbguns.co.uk/gg-105-co2-gg-105-co2.html?filter_name=HFC%20105

 

10% off voucher think was RC10 = £27 and free del on everything

 

like I said £27 - jeez a mag & del would cost a fair bit of that so bought a few

but they was hitting 400-450, now I might be able to use it

 

Other places do sell these cheapo pistols but not as cheap & delivered :(

but this bodge - and that is what it is ffs may just allow some cheapo guns to be used

 

PLEASE do not do this to any half decent pistol - get it done PROPERLY !!!!

if anyone wants to try this crap please remember:

 

EVERY GUN WILL BE DIFFERENT !!!!!

 

Another one - my other pistol may only need 1mm or 1.5mm shaved off

if I just dive in and take too much off too quickly it may drop to 100fps

I had got a rough idea with washers over valve stopping trigger hitting fully home

so I knew not to go too mad with dremel & files

 

Go very very slowly and gradually bit by bit - needless to say:

 

I AM NOT RESPONSIBLE FOR YOU SCREWING UP YOUR £125 CO2 PISTOL

(I am not very responsible or mature at all for that matter)

 

Only attempt this if you have a crappy cheapo gun, and a little common sense

and decent stuff - not your mum's nail file ffs

and can afford to lose the gun if YOU screw up going too mad

it may not work for all or other pistols so it is down to owner/user to decide

 

Not sure - DON'T DO IT, if not ready fine wait a while and will update if bodge still works ok

 

soz for long waffle - but I ain't gonna buy anybody a new gun if it goes pear shape on ya

 

ItsAJ - deffo spend £15 on the shop proper mod, my crappy gun is a non blowback 1911

yours is deffo worth £15 spent on it and can be reversed no doubt - my bodge not really

 

S D

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Well blow me - just found out not just every gun may different.....

 

But also every mag too will be different - kind of makes sense I suppose

popped new cart in another mag and was above 400 still after one mag of bb's ???

 

so each mag/valve may have its own slightly different "biting" point where valve opens

some slightly large/smaller bursts occur from mag to mag so to speak

 

could be slightly higher pressure from each cart but doubt it - same make/batch

do like these ASG carts they fit nicely and very little air escapes when fitting

plus they fit nicely in mag, press mag release and the mag drops out sweet like movies

other makes I used it needed a bit of help releasing empty mag

 

Hmmmmm - still more investigation & testing needed perhaps

will try the original 350 mag n see how that works....

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Wouldn't fitting a slightly stronger spring to the valve reduce the fps or packing the standard spring to increase spring tension?

 

I do this on my crosman co2 pistols.

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Wouldn't fitting a slightly stronger spring to the valve reduce the fps or packing the standard spring to increase spring tension?

 

I do this on my crosman co2 pistols.

if you mean the mag outlet valve then its not an ideal solution, on gbb guns the valve is held open until the slide/bolt has moved back far enough to disengage the hammer/firing pin mechanism, so even if a stronger spring stops the valve opening quite so much, at best it MAY reduce the muzzle velocity but will also increase the cycle time, and at worst will vent all the gas as not enough pressure builds up quickly enough to cycle the action. It is very hit and miss.

The only fully effective way of reducing fps is to restrict the amount of gas coming out of the air nozzle, which means reducing the amount of gas hitting the bb by either:

1. drilling through the outlet valve across its width with a small drill bit;

2. reducing the size of the outlet hole in the end of the nozzle (eg by fitting a short piece of tube inside the nozzle;

or 3. increasing the cross section of the floating valve inside the nozzle by building it up with plastic filler or similar.

All these are very much trial and error, get it wrong (particularly 1) and you kill your gun. I have a Tanaka Works K98 rifle that uses restrictors (as in 2 above) but that is bolt action nbb of course, however it does work to bring the velocity down very well. I have used (3) with the most success though in my CO2 mini Uzi and S&W Sigma- the cross shaped floating valve being built up with plastic strip and plastic filler, and then sanded down to more of a rounded profile a bit at a time and tested until it fires at a velocity I'm happy with. Alternatively if you know someone with a lathe a new floating valve could be made from aluminium easily enough, with key measurements taken from the original part. Modding this valve ensures the blowback and rate of fire stays the same too.

As said some trial and error is needed, its not a solution for everyone but with patience and basic tools it can be done.

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