I've had mine since about November and it seems to like the winchester 500 count bulk pack ammo fine now. At first I was having a problem with it jamming and also couldn't put all 25 rounds in the clip. After 150 or so rounds through it everything works fine now. I can fill the clip all the way and haven't had any jams since. I also shoot some winchester subsonic rounds through it. It feeds those ok most of the time. Every once in a while it'll fail to cycle one but I think that's cause they aren't a heavy enough load.