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Old September 15th, 2011, 03:32   #26
Not Eye Safe
ThunderCactus's Avatar
Join Date: Feb 2007
Location: with less oil industry than eco-hipster Vancouver
Most important thing is not necessarily barrel diameter, but barrel QUALITY. I've personally seen high quality 6.08 barrels outperform cheaper 6.05 barrels. As long as your BB doesn't hit anything, get redirected, and you maintain laminar airflow behind the BB, you get stupid crazy accuracy.

One thing that came up lately though is initial pressure.
And extremely important concept when comparing GBB to AEG.
For example, most of us use heavy ammo in pistols, even though they're only 280-300fps. You'll put a .25g or .28g BB into a STOCK 300fps pistol and get amazing range and accuracy out it.
Whereas if you put a .28g BB into a stock marui, even with optimal hop, your BB falls far short of a .20g!

So correct me if I'm wrong, but what I've figured is happening, is the AEG doesn't have enough initial pressure to get the spinning velocity it needs from the hop rubber. Because the piston starts it's travel so slowly, although there IS pressure being created, the BB may only be doing say 100fps when it leaves the hop rubber, and accelerates as it goes down the barrel. Of course the number goes down if you don't have a ported cylinder, since the piston doesn't have the velocity to build high pressure quickly
Whereas in a GBB, the propellant you are using is already compressed, and only needs to be applied. So right off the bat you start of with WAY higher pressure behind the BB. So when it leaves the hop rubber, let's say it's doing 200fps. So you get way more backspin on the BB, and with enough gas left to continue accelerating it on it's way out the barrel.

So my theory is based on the field performance of stock GBB pistols using heavy ammo, and both stock and upgraded AEGs of the same velocity using the same ammo. Infact sometimes of higher velocity, my 320fps HFC beretta was on par for range with some pretty nice 380fps AEGs...
Also, when you adjust your hop rubber, it's not so much the surface area of the rubber that matters, but the PRESSURE IT APPLIES. Making the gun require more pressure in order to get the BB past the hop rubber. And more initial pressure behind the BB means more inital FPS.

So if you compare a stock GBBR with a final muzzle velocity of 380fps on.20g BBs, with a stock AEG of the same. The GBBR should get better performance, because the GBBR can more effectively use heavier ammo, due to it's increased initial velocity.
Now comparing fully upgraded and tuned AEG's and PTWs (is it bad form to group those together? LOL), the gap isn't as far.
The only problem that occurs is in cooldown and ambient temperature, where your gas pressure drops (or raises) significantly, so it's going to have less short term repeatability over an AEG.
So like any other airsoft science, you can't use just one aspect to pick a gun. The GBBR will perform better stock, but it's a balance between how you shoot and the repeatability of the gun.

Ugh that's a mouthful
What do you guys think?
Tamiya connectors suck.
Originally Posted by swatt13 View Post
i never understood why the oil refinery had a brothel... i never see them at the refineries i work at this is bull!

Last edited by ThunderCactus; September 15th, 2011 at 03:42..
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