Guntec firing pin retainer - Guntec USA AR-15 Firing Pin Retainer

Great idea - works okay. The problem with this versus a standard retainer is that it is easily too wide, or so narrow that it can fall out. I took my rifle out today and fired roughly 1500 rounds, and when I took my bolt out for cleaning, it literally fell out. I am not sure if it broke or something else, but when I place it in originally, it retained perfectly. I am going to play with it some more tomorrow and see what could have happened. I have a regular spare that I will be using in the mean time and I am not sure if these are actually worth buying over a traditional retainer.