Just left the range and was having feeding issues with it. I purchased the upper complete and put it on my lower that I used to have a 300bo on. Most of the times it will eject the case, a few drove pipes. It will not pick up the next round. I was reading it should work good with a standard buffer tube and spring. I took video of it and it’s not going all the way back. I even cut back the spring some and nothing.