M.H.I.S Rifled Rifle!

[rna_duelers]

Actualy Rifling would slow a projectile down I would think as it addes more drag/friction in the barrel,but if the projectile is aerodynamic the rifling qould help it cut through the air and could aid distance a little but it would still slow the projectile down.

As for a piston valve I'm not going down that route.I would much prefer a QEV which is a piston valve silly me...

Your right about the rifling striaghtening out a little at one end of the pipe.That was the end I started from and the begining is the hardest part oh and i use the straightend out section of the rifling near the valve because of this I thought about the straight section rifling aswell.