So Scrapy's (the pieced together AR-15) first range trip wasn't ideal, by any means, but it was acceptable. First round of the Day. . . it shot! . . then that was it. It failed to fully cycle (short stroke). So I manually cycled and pulled again . . . CLICK ! No fire. So I checked the cartridge and discovered a primer strike. . . a very shallow primer strike. (keep in mind, the gun DID pass all of the safety tests before even loading) I continued through the manual cycling and occasional clicks, until I got a zero, then began to inspect the gun. Lucky for me the owner of the range drove his pickup around the area during this time and stopped to lend a hand. We came to the conclusion that the hammer spring was weak. We compared it to another AR and it was at most half as strong. The spring was changed (DPMS field repair kit) and I loaded another mag. I got about 5-6 rounds into the mag and I'd get an empty chamber or a double feed. We think (hope) it is a mag issue (AR stoner SS). The feed lips on that particular mag were uneven. I had the most success with a Magpul MOE and even a Magpul with a Nordic 48 round extension installed. But then I ran out of good ammo and it didn't like the Silver Bear that I had. . . that kind of bothers me, because my other ARs eat it up, so I bought a couple cases. Now I'm gonna have to keep testing, which I really don't enjoy. . . So it wasn't all that bad for a bunch of spare parts and my luck, which isn't so good usually.