Airsoft Sniper Forum banner

Advantage to Long barrels + Big cylinders?

6033 Views 16 Replies 4 Participants Last post by  chachaseeds
Is there any advantage to using longer inner barrels (with correctly matched cylinders, of course). I've heard very controversial reports on this subject. For example, take an SVD with a 690mm barrel vs an AK47 with a 455mm barrel, with both guns having correctly matched cylinders and near-perfect compression. Assume that both barrels are perfect quality and are very straight. Which rifle will perform better? Some people say that past 450mm barrel accuracy will go down, while others say a longer barrel will result in more accurate shots, even though the difference is minimal past a certain length. Does anyone have any test data regarding this?

I've also heard that longer barrels = more fps. Will a longer barrel + big cylinder have more fps than a shorter barrel + small cylinder? Assume C:B ratios for both barrels are ideal and everything else is the same. After all, why do people use long barrels and bore-up cylinders? And a longer barrel makes the rifle quieter, right?
1 - 8 of 17 Posts
Thanks for the reply!

But with fps caps and all, is the fps bonus worth it?
Ahh, that's interesting. I suppose an AK47 shooting at 450 fps will have the same performance as an SVD shooting at 450 fps, assuming they have the same internals besides cylinder and barrel, but the AK47 would need a heavier spring to achieve the same fps as the SVD. Interesting how people who want to upgrade their rifles to DMR's always go for the longer barrel.

But are you sure longer barrel doesn't make a quieter gun? Based on my experience, I'm almost positive that it does. To me it makes sense, as a longer gun means more "stuff" to absorb the sound.
That clears it up a bit... I was always wondering why M14's were much quieter than MP5's.
MP5 just needs a heavier ball.
Ahh you mean heavier BB :) :yup:
MP5 just needs a heavier ball.
Wait... then why does your DMR "make less noise when dry-fired with the barrel in than with no barrel?"

And I find the concept of widebores to be extremely interesting, although I haven't tried one yet.
Interesting. From my observations, I can still say that a longer inner barrel (generally) makes a quieter gun. Maybe this is because the air isn't escaping through the ports in the sides of a ported cylinder which is used for shorter barrels?
I really think it is just the length allowing more energy to go into the ball and less into the air at the muzzle.
Alright, I did my own research. It turns out that a longer inner barrel + larger cylinder generally means a quieter gun because:

"Another thing to note is that longer barrels tend to give a quieter "muzzle blast" if you will, because of the increased expansion room within the barrel. Even properly volume matched, a gun with a shorter barrel relies on using a low-volume high pressure burst of air which expands much more suddenly within the barrel. The longer barreled guns have more space to accelerate the bb, and thus the air leaving the cylinder is at a lower initial pressure and loses its pressure more gradually since it accelerates the bb over more distance."

taken from

Also, Noobie did a test regarding barrel length vs. fps. He matched a 500mm barrel and a 313mm barrel with cylinders which provided peak efficiency for the two barrels (all other components being the same) and found out the 500mm barrel got 520 fps, while the 313mm barrel got 510 (although he did say that he could have improved his C:B ratio for his 500mm setup by a little, so maybe the difference is a little more). He then upped the spring power on both guns and found the longer barrel shooting 18 plus fps harder. So I guess the FPS difference between barrel lengths is actually quite minimal. Noobie also said that there was no difference in accuracy between the two barrels.

taken from:

So in conclusion the advantage of using a longer barrel and larger cylinder is decreased noise (the "pop" of the BB being fired, not GB noise) and (very slightly) increased fps efficiency. I find it interesting that a longer barrel won't do much for accuracy or fps, although I guess a few free fps wouldn't hurt anyone!

Here is an example of what I just said. It's a chrono of the Echo 1 AKM and the Echo1 RPK. I'm pretty sure that they use the same spring and have similar internals, although the RPK probably has a larger cylinder. You can see that the RPK is shooting slightly (5-10 fps) harder than the AKM, and it is also has less of the "pop" noise while firing because of its 590mm barrel.
See less See more
1 - 8 of 17 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.