Using very long barrels

[Sniper12]

I have a 590mm barrel and I thought about putting it in an m4. I am not asking about accuracy, just would it increase range. Or I am told it may cause barrel, suck. Thanks

[MajorLandmark]

Re: Using very long barrels

Depends on what fps (and as an offshoot, rof) you are running. A 590mm barrel would need more than an M100 kind of fps output the avoid suckback. The faster the BB leaves the barrel, the less likely suckback is... the slower the rof, the less likely. I dont know the specifics in terms of numbers... but I am certain a 590 is too long for an AEG gearbox upgraded to a normal aeg level.

[The Keeper of Secrets]

Re: Using very long barrels

First thing you'll need is an unpoterted cylinder. That will remove any chance of suckbak.

Just to say, you won't really notice any difference. A much better idea would be to go with a tightbore barrel, you will notice a difference.

[Sniper12]

Re: Using very long barrels

I is a tightbore? Where do I get one of those cylinders?

[MajorLandmark]

Re: Using very long barrels

An unported cylinder reducing suckback? I dont mean to contradict, but that sounds contradictory in itself. Suckback happens because the piston starts getting drawn back while a BB is still traveling down the barrel. With a ported cylinder, some of the air is drawn in through the barrel, and then some through the port, once the piston reaches it. With a portless cylinder, all the air is going to get pulled in through the barrel... so if there is a BB in it, its going to get effected.

[The Keeper of Secrets]

Re: Using very long barrels

The theory I've always used is that an unpoterd cylinder allows for the full volume of air to be forced down the barrel, so it is made sure that the bb has exited before the piston reaches the end. and unported cylinder means that it is later in the piston's travel before the bb even starts moving.

[sj_asc]

Re: Using very long barrels

An increase in range is achieved by using good quality heavier bbs and hop up. Heavier bbs need additional cylinder volume to create higher exhaust pressure as well as compensate for leaks, as such using a shorter than recommended barrel would gain higher muzzle energy with heavier bbs than a longer barrel.

While the longer barrel would likely gain you velocity with .20g, it would be a lot less efficient with heavier weights.

On top of that, if you had an M4 with the standard barrel length of 363mm, it will more than likely have a 4/5 or Type 2 Cylinder which would need changing out for a non ported (Type 0/A) cylinder in order to retain muzzle energy efficiency with the longer barrel.

Regardless of bbs used/Cylinder type used, i would not recommend that barrel in a high speed setup.

[amandla36]

Re: Using very long barrels

Don't know if the mods will like this, but here goes anyway:
This guide might be useful:
http://www.airsoftza.co.za/forum/viewtopic.php?t=1572

[MajorLandmark]

Re: Using very long barrels

I think that answers everything quite well... The ported/unported.. is two sides of a coin really. I've never quite decided which aspect is more important for a high speed setup / reducing suckback ... But since this is about isng a long barrel, I'd agree that a full cylinder makes more sense. With speed as well, its more a case of comprimise. It's probably worth mentioning that with a long barrel thinking "ill just use it on semi" isnt a solution to suckback. Unless you are using a fancy electronically controled mechbox (with sensors and thing... or maybe just an active breaking mosfet), the gears almost always do more than one full rotation. This means that the suckback that matters (that which occurs right after the BB leaves the hop chamber until it exits the barrel) is still happening.

[Sniper12]

Re: Using very long barrels

Would it be worth cutting it?

[sj_asc]

Re: Using very long barrels

If you plan to use heavier bbs (.25g+) for better efficiency, otherwise leave it as it is.