Im guessing HP makes the paintballs go quicker/furthur?
Is there anyway to know how long between tests?
How long between tests - I've just picked up 2 tanks in the last few days, and I got confused on this one (but ended up with a brilliant deal). The earliest date on the bottle will be when it was born (it'll say like 2005/05, i.e. July 2005). Its first test is due exactly 5 years after this (so July 2010). There should also be a box where the date of retest is written in (when it gets it), though to be honnest I'd like to see a photo of a retested bottle to see what they write, because what stops you filling that in yourself (illegal and stupid, wasnt for me, was to avoid getting ripped off). PERSONALLY (note the emphasis) I wouldnt buy a bottle with less than 2 years of test on it, because while most bottles pass their test, a few fail, which means you'd only get a years use out of it (I would however buy it if it was dirt cheap, I take risks like that
).
HP making the balls go quicker/futher - right, heres the technical bit. The input pressure has (almost) nothing to do with your velocity and shooting distance ONCE VELOCITY HAS BEEN ADJUSTED. The difference between HP and LP is that HP will come out of the bottle and into the gun at a higher pressure than LP. Once it hits the gun however, some form of regulation will be done by the gun (even as basic as the old-skool Tippy velocity screws) so as to release the exact amount/pressure of air on a trigger pull to fire 1 ball at around 280fps (depending on what you chrony'd to). Other factors in velocity/distance are the barrel, and there are a few bolts for spyders and other more basic guns (venturi is it?) that reckon they put topspin on the ball and make it fly futher. Can't say anything as to whether or not this works or not.
End result - check whether your gun NEEDS a type of pressure (HP for ions, I think Vikings used to only take LP?) or if it takes either (i.e. egos), then select your gas system accordingly, adjust velocity, then mow some fools
.