I’m working on my first AR and have developed a problem. When I attempt to lock the bolt back, the charging handle/BCM has a lot of resistance or sticks.
I am using the following
Spikes stripped lower
LAR Grizzly stripped cosmetic blem upper
BCM bolt
Palmetto State Magpul LPK, charging handle, forward assist
The charging handle has severe deformation where it contacts the BCM under the gas port and on the top where it is dragging on the inside of the upper.
The buffer is a bit chewed up due to when I first assembled everything I was not paying attention and unscrewed the buffer tube causing the buffer weight to catch on the pin.
I think that it is the buffer weight causing the problem. When I first noticed the issue. I rotated the weight and that seemed to solve it. but now the bolt and handle are sticking.
This weekend there is a gun show, so I will be able to pick up parts to fix this problem. Any insight you have is a big help.
IDK but it looks to me like that “ridge” in the top of the channel for the Charging Handle might be some of the problem? Looks like ridge wedges the
CH down into the BCG. Wonder if it requires a special CH? Is the ridge some kind of special upper feature??
Ain’t sure why the Buffer is messed up like that unless you didn’t have something installed correctly. Kind of hard to tell but maybe the RE wasn’t
screwed in until it was over the Retainer Pin to hold it in place, so the large part of the Retaining Pin was sticking up too high and the Buffer was hitting
Pin (and the rear of the BCG too)?? Do you have ding marks on the lower rear of the BCG, around the groove on the bottom?
If you remove the Buffer, does (or did) the Retaining Pin come out?
Have you swapped the Bolt, BCG, CH in another AR to see if it has problems.
The ridge is from the charging handle dragging on the inside of the upper.
When I was unscrewing the buffer tube, the pin came out a bit and that is what caused the damage to the weight. The bolt is good.
I deburred the charging handle where it was deformed and around the buffer weight to see if that would help, but that did nothing. When pulling the handle back, the bolt goes into a bind right where it should lock back on an empty mag. If I tap the receiver the bolt springs back home.
I thought there might be an issue with the hammer pushing the bolt up to much and causing the bind, but some times it is just hard to pull the handle back or it sticks.
Ill pick up a new weight and handle this weekend and see if that fixes my problems.
First of all, if I am reading your assembly correctly, you installed the reciever extension with the spring and the buffer inside of the tube? Is this right? You should screw in the RE and then push down on the buffer detent without the spring and buffer in the RE when installing. After indexing the buffer tube lip over the top of the buffer detent, and torquing the castle nut to 30-45 lbs, THEN you put the spring and buffer in. Then stake and witness mark the endplate and castle nut.
That channel that is being dug out of the upper receiver is normal. I ahve that same mark on all of my uppers.
That deformed charging isn’t right. Something funky going on there.
ETA: The buffer detent should be captive by the reciever extension. It should cover the bottom thicker portion of the detent and spring, and the pointy part should prevent the RE from being screwed in further. You f’ed your buffer up pretty good, but it should still be fine. I would look at the detent spring because I bet is is all kinds of mangled right now and if it isn’t, then you got lucky.
Looks almost like the charging handle is out of spec? Ive never seen that before. It almost looks like the forward end is too “tall” and is being smashed by the BCG which is putting upward pressure on the charging handle causing the scrape marks on the roof of the upper reciever but i could be wrong wich wouldnt suprise me if i was. Also have you tried changing out charging handles?
The wear mark on the interior of the upper receiver isn’t unusual, but just about everything else is all FUBAR. Light wear on the inside edge of the charging handle is expected after a bit, but that half moon looking gouge is hideous. My initial though was the charging handle section there was too wide, but even if so, the point of contact with the bolt carrier is flat and does not necessarily explain the odd shape where material is peened away. I’m not following you on the description on how the buffer ended up like that. I guess the fist trouble shooting step is to try a different charging handle.
Is your upper complete? What type of barrel do you have? {the first pic looks like there is no barrel}
Have you tried to fire the gun?
Is this your first and only AR? If so then what are you using as a reference or for instructions for your build? You may be doing steps out of order causing you to screw stuff up.
Excellent question. Did this damage occur while firing a complete upper or did you do this while test fitting the parts together? The mark along the top, inside the upper is normal from what I can tell. However, your charging handle is fubar from the damage on the end. How did that happen? Also, the battering and burrs on the buffer may be making contact inside the buffer tube & causing drag. You need to replace the damaged parts for starters and maybe reconsider your inclination to build your own upper.
Regarding the half moon/rounded gouge on the underside nose of the charging handle.
I’ve seen simular once before: when an “assembler” didn’t know that the nose of the handle went into the big hole in the receiver then dropped into the the groove once the side lugs were aligned with the milled relief in there.
He got the upper locked into a vice, slid the charging handle straight in the groove from the furthest back end, then when the side lugs stopped further forward progress, a long flat end drift and hammer were employed to ‘pop that SOB into place’. (because being the bright young spark he was, he thought well ahead and didn’t want to risk bending the handle by beating on the T end directly…)
I have not purchased a barrel yet and do not own another AR to swap parts around. With the charging handle removed, I used a wood dowel to push the bolt back and it does not bind up, locks back on an empty mag and returns home with out issue. Same thing with the buffer there is no binding when it is pushed back in the tube. I will pick up a new handle tomorrow.
Get a new buffer and charging handle and let someone that knows what they are doing build the upper and lower for you. I think what happened was you don’t know what you are doing when putting parts together and during your “function” testing, something wasn’t installed right and you were trying to force something that shouldn’t be forced.
please explain how you did this. did you push on the BOLT or BOLT CARRIER? i don’t see how you did that with the charging handle removed. if you push on the front of the bolt, all is does is lock the cam pin in the cam pin recess and prevents the bolt and carrier from moving backward. so, i’m VERY curious as to how you pushed the bolt back with a wooden dowel. if you meant bolt carrier, show us with a picture to show how you did it.
when you locked “back on an empty mag and returns home with out issue.”, how did you know it returned home without issue? did you press the bolt catch and allow the carrier/bolt to return forward under spring pressure? i bet that’s what you did.
based on what you wrote, i can’t see how or why you performed this operation without the charging handle: "With the charging handle removed, I used a wood dowel to push the bolt back and it does not bind up, locks back on an empty mag and returns home with out issue. "
what i think happened is that to test whether it locked back on an empty mag, you had to have installed the charging handle. you used the charging handle to lock the bolt back on an empty mag. to return the bolt home, you pressed the bolt catch, sending the bolt forward under recoil spring pressure. that would be fine if you had a barrel installed. without a barrel and barrel extension to stop the forward motion of the bolt and carrier, the only thing stopping the bolt carrier’s forward travel is the charging handle, right where it’s damaged. the bolt carrier slammed into the bottom of the front of the charging handle, creating that gouge there. that’s exactly the shape of the step in front of the cam pin slot in the carrier, below the gas tube.
the forward motion of the buffer is not stopped by the buffer retaining pin under normal operation. it stops when the bolt carrier stops in the forward position. but, since you don’t have a barrel, and the carrier was free to move further forward than it would normally do, the buffer slammed into the buffer retaining pin (causing the damage to the buffer face), while the carrier kept moving forward.
in other words, it all got messed up because you were function testing without a barrel.
Perhaps the dings on the buffer are from repeated releases of the BC. With the BC free to move too far forward the buffer would be stopped totally by the retaining pin.
I’m amazed by the number of people that try to build an AR with no clue at even where to start… :sad:
that_guy,
I’m sure you intend well but I think that you need to step back from your project and either look for someone local that can help or do a bit more home work on the subject. Remember that when this weapon is finished you are going to place it up next to your head and fire it!!! Yourself and/or others around you can be very seriously injured if you cobble this thing together wrong.
For your first AR I always suggest a couple of things:
Buy a factory built weapon
Unless you have a military or LE background and have trained on this weapon you need to seek out proper training.
Save the home brew guns for when you understand what’s going on.
I’ve owned a few AR’s in the past but I’ve only built one lower and swapped out all the parts on another; my goto AR (BCM) is built to a standard at the factory. { I build military weapons (M-240) but I don’t have have enough experience to build an AR upper that I would trust my life with}