Appreciate that josephlys!
I was really suprised with using a ball valve! i was going to go with a trigger system of some sort, but while i was getting parts, i was this and though Meh why not!
To be honest i prefer the ball valve over the one i am using on the fire extinguisher gun because it lets WAY more air out very quickly.
My valve is quite smooth to turn, and even under pressure is very easy to turn, you can just put some sort of lube on it to make it smoother (

)
My sniper is VERY accurate and as it is in the somewhat shape of a gun, You can hold it very well so that there is hardly and movement at all. Although, when using the bipod and in the prone position, You get no movment at all!
I am not sure how much i am filling the fire extinguisher one up at, my gauge dosn't go up high enough to check!
I need to get a new gauge!!!
Out of all of them, Overall the best is the sniper, It is powerfull for its size (Well its actually quite large in person) and VERY accurate!