SRC Ak74u

[Siphon22]

So Ive recently purchased a GBB SRC ak74u, now stock they fire about 380-400 fps. Short of buying a NPAS system for it from somewhere, Im attempting to lower the Fps a bit by adding a silencer and possibly going from .20g to .30g BBs.

Anyone got any ideas on other ways to lower the fps a bit?
Be a huge bummer to not be able to use it on sunday because otherwise Im really happy with the gun itself.

[Flazzbog]

The power limits of your gun are based on the energy of the projectile, which we usually quantify by saying "350 fps with a 0.2g bb". Which equates to 1.14 Joules.

1.14 Joules is the actual energy limit for semi auto guns at tag. So if you're shooting over 350fps with 0.2g bbs, changing the weight would not help you. you'd need to be shooting under 284 fps on 0.3s to be under the limit.

Just so clarify, if you're shooting at 400 fps with 0.2g bbs, you're at 1.48 joules which is about 25% over the limit. Putting 0.3s would be get you 325 fps which is still at 1.48 joules and still over the limit.

So you're gonna need an npas

Theres an fps energy converter http://www.arniesairsoft.co.uk/?filnavn ... s_calc.htm if you wanna have a look at it. I think Acey made one too which is around somewhere.

[Siphon22]

I havent chronoed it yet so not sure what its currently shooting at but hopefully the silencer would bring it down a bit too. Otherwise Im not even sure there is an NPAS system for the ak74u. I know theres one for WE`s AK74u but not sure about SRC`s.

[Siphon22]

Ive also heard shortening the spring can lower the fps as well, otherwise if all else fails I might have to go play with CSG I heard their fps limit is a bit higher?

[ReaperNet]

Wrong, their fps limit is the same as ours; 350fps on .2

NPAS man, i'm not sure there is a way around it.

[Siphon22]

Ive had a look for NPAS for an SRC AK74u, seems only WE makes one for their AK74u. I may be royally screwed.

[Argonaut]

I havent chronoed it yet so not sure what its currently shooting at but hopefully the silencer would bring it down a bit too.

If I were you, Chrono it before making too many quick decisions about cashing in for new components which may or may not be compatible/do what you think it will do.

[Siphon22]

Ill bring it along on sunday, hopefully Ill be able to use it; if not the ole M4 will have to do.

[Rawr]

personally i dont see how a silencer could bring down the fps... as i had a silencer on my ak47 and im pretty sure there was no change with or without it.


Edit: plus this is talking FPS not joules. if a silencer does bring down the FPS it may not bring down the joules, so it will still be over the limit.

[Siphon22]

apparently the silencer adds length the bb has to travel reducing its fps by a bit (so Im told anyway) Ive had a look for NPAS kits but most increase fps rather then lower it.

[Siphon22]

Took my m4 apart trying to fix the full automatic problem, gave up in defeat. Now it's working again after I put it back together. Weird

[Sneakers]

That solves the majority of my problems. Take it apart, discover there's nothing wrong, put it back together and its fine.

[Siphon22]

It would only fire fully automatic 3+ round bursts, sometimes indefinitely but after taking it apart. Seems to have changed it's mind and gone back to semi auto. Meh

[Flazzbog]

Taking them apart and putting them back together again often solves whatever problem is wrong with them. It's werid.

However I'm pretty sure the problem you've described is what happens when the squeezy part of the trigger mech is too tight. if it happens again just pry it open a wee bit (but not so much that it doesnt make contact on both sides) and it should solve your problem.

If it goes fully auto indefinately, it means the cut off lever has broken or you've lost the tiny spring on the selector plate on the outside of the gearbox.

[Siphon22]

I did take the trigger bar out when I took it apart so that might have fixed it as you said, fully auto is fun for a while... But loses it's charm eventually, happy to have semi auto back.