Well here's how the saga began. I was shooting some reloads using some Surplus WCC844 that turned out to be shit. Half the expected velocity, only about half the powder actually seemed to burn, the rest just served to make my rifle filthy.
The rifle.
Factory M4 Colt upper and barrel, Colt bolt and carrier, preban Colt lower, Jp trigger, stock colt factory hammer,spring, and disconector, Aimpoint, ggg buis, PRI front sight, Giles tactical sling, BMAS, KAC grip, Surefire light, Redi-mag, ZM weapons comp. About 2K rounds thru it with the only probs being mag related.
First problem. Carrier jammed (while firing)so bad over the hammer, I couldnt get it unstuck with anything I had with me at the range. THe carrier was half way into the buffer tube and stuck there. Took it home pulled the stock and buffer tube off and used a small screw driver to push the hammer down and got everything apart. Other than being filthy, I could find nothing wrong. Disconnector works fine, saftey works, firing pin looks good. Hammer and trigger pins are straight. So I clean, lube (molyslide) and reassemble. I also cleaned the remainder of the rifle.
Second experience.
Back to the range today. Same rifle. SA ammo that has run fine thru this AR and every other I have. Yes, its not the cleanest burning stuff, but good velocities and accurate. I load up the first mag with 20 rounds. Shoot about 15 rounds - everythings fine. Unload rifle to help a buddy set up some targets. Insert mag with 5 rounds. While holding the foregrip left handed. I pull back the charging handle, with my right hand and release to chamber a round - BANG. No finger on the trigger. Selector set on Fire.
I then take another mag with 20 rounds and cycle them thru the action trying to get it to fire using the same procedure as above - Nothing. I then tried shoot 2 rounds, pull the charging handle back (ejecting a live round) and release - Nothing.
Shoot 100 more rounds slow, fast. Everything works fine. An inspection and function check of the disconnector, saftey -- Normal.
So do you guys think I just had some (too much) grease on the engagement between the hammer and trigger? Or dirt/unburnt powder somewhere? Or What? I did check the JP adjustment screws and they havent moved since I glued them 1K rounds ago.
This things really starting to spook me since its my house gun. Im baffled as to the problem. I can let the first episode go to filthy, crappy powder, but this is getting to be a bit much.
Thanks for your help.