[Dirty Deeds]

I recenty took my SR16 (frankengun) and was doing some experimenting of my own.

1 - Full cylinder with a 509mm barrel was shooting at 392 FPS.
2 - I replaced the M16 barel with a stock M4 barrel and the FPS dropped to 375.
3- I recently bought a silencer to replace my homemade silencer that was covering the M16 barrel, it turns out the new silencer was about 22mm short and I hade to cut the barrel. After all was done the gun now shoots at 396 FPS. Which means a 487mm barrel is better matched to a full cylinder than a 509mm barrel, thus making better use of all of the air in the cylinder.

You could put a 300% spring in your gun, however if your cylinder and barrel are mis-matched (same volumetric space, cylinder and barrel) you loose alot of air pressure and may end up shooting 320 FPS and doing major damage to your mech box, When using a full cylinder and short barel (piston slamming with lots of force, due to no back pressure, for no reason).

The oposite would happen with a ported cylinder and a long barrel. Not enough air volume to maintain the push on the BB to the end of the barrel, would result in friction between the BB and barrel as it exits, slowing the BB before exiting the barel.

So in my opinion and tests, before you do any upgrades, make sure your barrel and cylinder are matched as closely as possible, as the spring only effects how much pressure is exerted (higher air velocity), not how much air is actualy expelled. Expelled air is determined by the cylinder size itself. Ideally the piston should strike the clinder head a nano-second before the BB exits the barrel.

Sorry if this was already covered.