its ok they can be picky about ammo types or you get fail to feed sometimes bursts
I replaced the springs in mine and this fixed the problem
mine hated dynapoints but loved the cheap bulk federals at crappy tire
parts you cant get you cant get extra mags ciener is a reall ass and none in canada deals with him anymore as far as i understand
its very acurate in my m16A1 upper with a 1/12 twist but sucks in my 1/7 or 1/9 uppers
as for worth the ones with the 30 rnds mag(s) are worth more i got mine on here for $80.00 shipped with 1 30 rnd mag used it was a steal id say at least double that is the going rate but i could be wrong