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Discussion Starter · #1 ·
About 15mins ago I saw a thread that was talking about Cylinder length compared to Barrel length, I'm going to ask you guys because theres no one on AO that has as much experience with Spring rifles as you guys do.

link: http://www.airsoftohio.com/forums/showthread.php?t=19159

jist of conversation: The larger or shorter the barrel in you gun, the larger or shorter the cylinder should be in the gun too. They stated that this should match(509mm barrel to M16 cylinder).

my Q: Does this not also apply to spring rifles? If it does what are the appropriate lengths for the barrels with the stock cylinders? And finally, Would a bore up cylinder be needed instead of a larger cylinder(I just saw these boreup cylingers on UN company I think).

Thanks guys, I dont even know if this applies to spring rifles.

sticks
 

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Well first of all yes, the cylinder displacement to barrel length ratio does effect your velocity. If you have a standard V2 AEG cylinder with say a 650mm barrel, there will be something called "barrel suck" where you will actually lose velocity.

As for spring rifles specifically, you shouldn't have to worry about barrel suck because in a spring bolt action gun the cylinder is rather large to begin with and it'd take a HUGE barrel to produce barrel suck. As far as I'm aware of, you can't buy a 'larger' cylinder for any bolt action currently on the market. A link to what you're talking about on UNcompany would be nice.

In conclusion, if you're worried about this problem and you have a spring bolt action rifle.. don't. You'll be okay because of your large bolt action cylinder. That's actually why we can reach such high velocities with our guns, we have a lot more air to push the bb with(also thanks to our strong springs).

The basic equation is that if your barrel's displacement is larger than your cylinder's displacement then you'll have a problem.
 

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I did some research into this last year. It came out that there is an ideal ratio between cylinder and barrel, which for those that are interested is the cylinder should carry 1.6 to 1.9 times more air than the barrel. Like Embed said it doesn't really affect Spring Sniper Rifles for the reasons he indicated, its more of an AEG thing to increase efficiency in short stroked, fast and/or short barreled guns. This doesn't mean that the principal cannot be applied to a Spring Sniper Rifle in fact it might have positive effects, but as i don't have a spare cylinder for my VSR I am reluctant to experiment with it.

Here is a pic of what I did to my M4s cylinder when I cut the barrel to 4.5" long, sorry for the quality but camera phone tecnology ain't all its cracked up to be ;). The section to the right of the line and holes is the end that the cylinder head goes in.



This is the modded gun



I still need to make a battery for it yet, and when its finished it will be my PDW.
 

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Discussion Starter · #4 ·
Thanks for the replies guys,

I wasn't really worried that I would have the suck but I just didn't know if there was a correct length to optomise the airflow..

Vindicare: was that with a stock cylinder? Luckily the smith that upgraded my gun put in an M16 length cylinder when I upgraded my barrel :) .

Thanks again. I'll try to get the link tonight, I can't copy paste on an I touch :)

sticks
 

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No, it was an M4 cylinder with the large oval hole at the other end, it was recommended that several small holes are better than one big one as its less likely to ware a naffing great chunk off of the side of the 'O' ring. I have short stroked the gun to the point that the cylinder doesn't go as far back as the original hole to completely eliminate this problem. You could theoretically use a standard cylinder and just multi-port it, I only short stroked the gun to provide superior suppressive fire ;)
 
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