i have 1, my m9 does the same thing, its b/c of the design of the mag, when u take it out it always drops a few, u should just make sure that its out of bbs b4 taking it out, about it rolling down the barrel, i think ur mag may have a really big leak or u rnt filling it up enough, and dont use 134a for it r it wont work 2 well, make sure u hold the gas in for about 6 seconds, if that doesnt work u have a really bad leak which may be do 2 a bad o ring in the mag, or maybe its just the spring is out of place(try the 1st thing i said, if that doesnt work i can give u steps on how 2 fix mag if thats the prob)