Here's a quick way to burn through some cash. How much did you pay for 100 rounds of 556? I'm using the Slide Fire Bump Fire Stock and a Korean KCI 100 drum magazine. I found this setup to run best using brass cased ammo and not the steel Wolf type ammo. Be aware that shooting your rifle like this can get expensive both in ammo and replacing parts on your gun as you break stuff. Stay tuned for the full review of the bumpfire stock. There are things you NEED to know about this if you plan to buy one.