Problem with DPMS 18" fluted bull barrel upper assembly
Posted 01 December 2010 - 02:55 AM
I was following DPMS's instruction for break-in the barrel. The ammo used was Federal 150 gr soft point from Walmart. I loaded one round to Pmag (Magpul 20 rounder), fired it. Cleaned the barrel; loaded another round to mag, chambered and fired it, no problem. Cleaned barrel again, loaded 2 rounds in the mag, the first one fired, pulled the trigger again, nothing happened. Now, with a live round in the chamber, the bolt was not completely closed, I couldn't remove the round from chamber, the bolt was locked. Luckily, I was able to open the bolt with a padded screwdriver and removed the live round. I then inspected the feeding ramp, it was rough.
My best guesses are: 1. the buffer spring is too strong that the bolt was not fully pushed back to correctly chamber a following round; 2. the rough feeding ramp dragged the following round and in combination to possible problem 1; 3. resulted from soft point ammo; or 4. had something to do with headspace.
I change to regular AR15 carbine buffer spring, re-cleaned and re-oiled the bolt assembly, polished feed ramp with dremel polishing wheel. This time I used surplus ball ammo for a test. It was better, one of five round got stuck with the bolt not complete close, forward assist didn't help. It was not as tight as before. I could eject the round forcefully with the charging handle.
My thoughts are that the bolt assembly is still tight, and feeding ramp still needs some smoothing and polishing. I assume that the upper assembly should be headspace at DPMS and test fired. Before I try shooting again, I would like to hear from experts here so I could avoid incidence or damage to me/my rifle. I appreciate your inputs.
Posted 01 December 2010 - 03:27 AM
Posted 01 December 2010 - 03:28 AM
Posted 01 December 2010 - 03:30 AM
Posted 01 December 2010 - 03:42 AM
But yes.. ALOT of people have used the std AR15 buffer & spring and had the same - results.. keep the 308 one in an you should be G-t-G..
Posted 01 December 2010 - 03:46 AM