Hello all. Long time lurker; first time poster.
I put together a new AR-15 in 450 Bushmaster this month to take advantage of the recent changes to the Ohio hunting laws. I got a GLFA upper from Midwest Firearms, a PSA lower half with the EPT trigger and ACS-L stock, and AR-Stoner mags from Midway. Topped the thing off with a Bushnell TRS-25 red dot with a dab of lok-tite. Bore sighted it at home and took it to a range last night to zero it in. What a disaster!
I managed to fire 8 rounds in 30 minutes. 2 light strikes that dimpled the Hornady ammo, but did not ignite. 1 FTF that required 2 hits on the forward assist to chamber. 1 FTF where it just didn't pick up the round from the mag. Twice the extractor didn't grab the shell. 4 shots required me to turn the gun to "safe" in order for the hammer to cock (always on a follow up shot). Not a single hole in the paper (18"x18") at 25 yards using a lead sled.
I haven't done any customization other than to add a QD end plate for a sling, so the only work I've done myself is inserting the pins to attach the two halves. I thought I was having problems with just the upper until I started to see the hammer cocking issue. I admit I'm not using top shelf components, but I do expect the thing to go bag when I pull the trigger!
I have another (inexpensive) AR that I put together out of a compete upper and complete lower that has the light strike problem on the first shot after sitting in storage, but none of the other issues. I have no idea what's going wrong. Any help is appreciated.