I have nver had trouble with mine till now but they worked for like 2 years, but they are doublestack mags so if you use ###### bbs like excel they get stuck in the mag.
you can also cap the mags so they only can take 70bbs, then they feed even better, i think i need to do that now after my spring have got weak after 2 years of playing evry Tuesday and saturday of the week.