AR build problem.

[Fred762]

Son and I finished an AR receiver "from scratch build" a few weeks ago.
We wanted to use a "new upper" . We got our 'lower' completed and found a problem which I have never seen in 30 years of messing about w ARs.

The "new"upper (we ordered from XYZ corp) and our lower mated well, and everything seemed ok. Cocked ok, New carrier w bolt slides in and out easily, etc..but after closing the action & dry firing once, it becomes imposible to draw back the charging handle!

WE tried everything we could think of ....even a couple of different firing pins, thinking the pin might be slightly bent, etc..no help. When hammer was put in cocked position and action then closed, the charging handle would easily draw back the carrier. But, after dry firing we could not pull charging handle back. Opening the action, we found that we could not withdraw the carrier by hand....it took several taps backwards, with a small hammer, onto a plastic strip inserted into the "hammer cut out" of the carrier ...to free it and remove the carrier. It could not be done w the charging handle..even w action open.



Finally in frustration, I took a complete boltB from another AR15 and tried that in the new carrier and upper..perfect functioning. Took the new carrier and replacement boltB from the new upper and tried them in the "old AR upper"..perfect functioning again.
Tried a third bolt..perfect functioning. So..what should we do? The new carrier works well in both uppers, with the replacement boltB I tried. I tried the new bolt alone w the FP and an older FP.....the pins stick in the FP hole. I am wondering if the supplied bolt has the FP hole drilled a tad off center?? Pissed me off and I've never had this happen in 30+ yrs of messing about w ARs!! Ideas?? ASide from sending back the supplied bolt that is.

[Hawk]

On the BCG, can you (easily) manually compress and extend the bolt in the carrier? If not, then look at the fit and lubrication of the 3 gas rings on the bolt.

[Fred762]

bolt easily drops into carrier..FP sticks in FP hole.... sent it all back to mfr for replacement. Upper works well w diff BCG and bolt wierd & new to me.

[ar15jules]

That's odd.

[ianb1116]

What's the BCG manufacturer? Some BCG's are tighter at lockup than others but you shouldnt have to morter it with an empty chamber.

[Fred762]

What's the BCG manufacturer? Some BCG's are tighter at lockup than others but you shouldnt have to morter it with an empty chamber.

WE LITERALLY HAD TO SLIP A PLASTIC PAINTBRUSH HANDLE INTO THE CUTOUT FOR THE HAMMER IN THE BC( action open) AND THEN TAP BACKWARDS W A SMALLISH HAMMER..CAREFULLY. NO RD IN CHAMBER OF COURSE. I tried pulling bolt and FP out and slipping FP in to bolt only..the FP sticks in the bolt!! Could not tell if bent or just off center FP hole...all sent back to supplier. Tried the BC w a different bolt and FP..all worked smoothly in new upper. Tried new BC w diff bolt and FP in older AR upper x2..smooth. wierdness!!

[prsndoc]

Only thing I had that was clowas fixed with lune.

[:-)]

Take the bolt out of the bolt carrier, put the firing pin in and tap on it. See if the pin gets stuck.
I've had the same problem with a new bolt before.

[Fred762]

Take the bolt out of the bolt carrier, put the firing pin in and tap on it. See if the pin gets stuck.
I've had the same problem with a new bolt before.

WE did that..the FP..actually 3 FPs we tried got stuck in the bolt..and bolt was NOT packed w cosmoline either. Corp is sending whole new upper. BCG and bolt..should be here today or tomorrow.

[Everready73]

What brand was the BCG?