which cylinder for a G&P?
 

What cylinder for a 300mm barrel and a corrected aoe sorbo of 3/16?
I am afraid of over/under voluming.
I have the stock tapered barrel and this: http://www.evike.com/product_info.php?products_i=38479/
The stock cylinder might not have enough volume because the aoe is corrected 3/16.

Why are you afraid of over/under voluming? That just means you won't be getting the best FPS your spring could output. You shouldn't be worried about breaking your G&P shell unless you are attempting an extreme build.

Typically a Type-1 cylinder (M4 hole) is used in that situation and general 350-400fps range.

promtheus type C for 300-400mm barrel, which is probably M4

firstly, who knows what barrel they're using to determine this, a 6.08 needs more volume than a 6.03
second, always be on the high side. So if you have a 300mm barrel, you want a cylinder for a 300-360mm barrel instead of a 250-310mm barrel or whatever
third, those stock barrels are terrible lol

Ok guys thanks for your help I think I'm paranoid I forum surf too much.