sniper rifles in general

[Ironaeon]

I wanted to ask how the inner barrel length affects the overall accuracy. example: L96 500fps with .20 bb's. feeding it .36's and extending the stock barrel to an barrel around 8" longer. how would that affect the accuracy? or flight path of the BB?

[L473ncy]

Probably detrimental effect. Yes it does increase the time for "stabilization" but you also get more time for the BB bouncing in the barrel.

You have to realize that airsoft guns are literally muskets, there's no rifling in the barrel (and even the TK Twist is designed to provide a "cushion" of air not act as rifling).

If you can find a mathematical equation for the length of barrel vs the bouncing affecting final accuracy it then just becomes an optimization problem, however I suspect that a ~368mm barrel will be optimal.

Also note that there is a limit to the speed of the BB as well, you want laminar flow of air around the BB and at some point with a high enough FPS turbulent flow takes over and the BB will fly wildly.

[Jaco14]

Stock barrel is 495mm + 8"(203mm) is just under 700mm afaik 650mm is the longest barrel

Putting a longer barrel on any gun isn't necessarily an upgrade and can cause performance issues

Your barrel length should be reflective of the volume of air in the cylinder, Otherwise your cylinder won't have enough compression to move the bb all the way out of the barrel before losing pressure .

This can cause decreased range and or accuracy problems

[Ricochet]

You need only enough barrel for the BB to stabilize, which isn't usually much. Also the longer the barrel, the easier to get barrel fouling, which is dirt and crap. A BB shouldn't bounce necessarily. The hop-up should push the BB upwards against the top of the barrel from the backspin, until it stabilizes. Different effects have been noted in different barrel types, lengths and bores. However, your most effective and reliable guns don't show much difference between lengths, such as carbine, rifle and CQB, etc. Tighter bores than 6.03, 6.04 won't help with accuracy and consistency. Some like the wider bore such as 6.10, but you may need to increase your spring power to make up the velocity loss.

[grantmac]

Never need anything tighter than 6.03 or longer than 450mm. Anyone telling you otherwise is selling something.

A shorter inner barrel with a correctly volumed cylinder will be the best combination. Almost all VSR based rifles are very over volumed which results in excess noise and energy creep, that is where the recommendation for longer comes from, a better solution would be a ported cylinder.

Grant

[FOX_111]

Stock lenght rifle barrels are enought.
You just need to install a tightbore if it's not stock with it. The hopup has a stronger effect on acuracy. Then, the piston and cylinder need to be upgraded for power, durability and consistency.
That's why tuned quality sniper rifles cost around 1000$ and up when done.

[L473ncy]

Originally Posted by Ricochet

You need only enough barrel for the BB to stabilize, which isn't usually much. Also the longer the barrel, the easier to get barrel fouling, which is dirt and crap.

This coming from the guy who tries to get the longest barrel possible on his guns? Or is it because you also want the leverage just in case you need to use it as a pry bar, spear, or a bat.

[ThunderCactus]

You don't need a barrel long than 5", but it depends on a few factors.
Short of it is, with the fixed volume cylinder of your rifle you're best off running a 400-500mm barrel. Too short and you'll get underpressure and over volume.

Basically, two guns shooting 1.48j, one 10" and one 20". The 20" barrel uses much less pressure applied over it's length to accelerate the BB to that velocity. Less pressure means less centering.
Longer barrels are also more prone to accuracy loss due to fouling, and in a bolt action rifle you notice it right away.
With my 430mm 6.03 barrel on my VSR, I noticed accuracy start to go down after just 120 rounds.

So don't run any longer of a barrel than you need to. You might THINK it provides a benefit over the stock barrel, but that's just because you're going from a stock barrel to a high quality barrel. Ultimately the longer barrel will be more detrimental.

[Ironaeon]

aah yes I see what you mean.

so getting an better barrel is more functional, hop up as well so then other things would include innards around the spring and what not.

back to the barrel length, using lighter shots would allow it to maintain efficiency and heavier ones would strain the systems capacity to push it the complete length?

also what is an ported cylinder?

[ThunderCactus]

Heavier BBs are more effective.
Range is ultimately determined by the weight of your ammo, heavier BBs have more potential to go further.
Then, you need the muzzle energy and hopup to get them out to their maximum potential.

Ports on a cylinder reduce the air volume available. The major advantage being, on short barrels with ported cylinders, that the piston already has a lot of forward momentum before it begins it's compression. So you start out with higher pressure air than you would in an unported cylinder. This is the primary reason why short barrels are as effective as long barrels.
If you put a full cylinder on a short barrel, you'd lose a lot of muzzle energy, requiring a much stronger spring, and creating a lot more wear and tear on the mechbox.

A very basic and easy to do test to check if you're running heavy ammo effectively is to chrono with a .20g BB, then check your muzzle energy, then chrono with a heavy BB, and check it's muzzle energy.
If you have a gain, no matter how slight, in muzzle energy, you're running efficiently.
If you have a loss in muzzle energy, it means there isn't enough air volume being pushed down the barrel.

[SuperHog]

I don't have a single barrel on my rifles with a bore less than 6.03mm. 6.03mm on them all.

As for pistols, 6.01mm works great.