"I bought two of these with my H&K SL8-1. What can I say more than that these magazines seem pretty disappointing. I would assume that I'd have a better performance out of 130 round mid-cap magazines than wind-up magazines but I'm seriously mistaken. The 16 round low-cap magazine that the SL8-1 comes with performs better than these magazines. They don't feed fast enough or well enough for full-auto fire, let alone even semi-auto fire. I even went so far as to use some liquid wrench lubricant made for plastic (so as not to corrode the parts) and it still continues to fail expectations. I hate how the only G36 magazines I can find are all made by DBoys. I'm thinking I might try my chances with 50 round DBoys; see if they perform any better."