AR Not Picking Up Rounds

[DirectDrive]

Just seems odd to me that on a closed bolt I can't get it to strip off a round when I pull the charging handle. I am pretty sure the issue is me, just not sure what else to check. As noted above, maybe the buffer is something to take a closer look at.

1) Rifle cycling = round will chamber
2) etrain cycling = round will not chamber

Confucius Say etrain not pulling BCG back as far as rifle

Could be that the buffer spring you're using is very close to "coil stacking" and the added oomph on the BCG during normal cycling is enough to overcome it.
Pulling the charging handle back to what feels like full stroke, apparently is not enough.

Also there could be some crap in the bottom of the buffer tube.
It has happened.

The buffer tube could be out of spec and not deep enough.
It has happened....Chicom part.

The buffer could be out of spec.
(too long)

 

[etrain16]

1) Rifle cycling = round will chamber
2) etrain cycling = round will not chamber

Confucius Say etrain not pulling BCG back as far as rifle

Could be that the buffer spring you're using is very close to "coil stacking" and the added oomph on the BCG during normal cycling is enough to overcome it.
Pulling the charging handle back to what feels like full stroke, apparently is not enough.

Also there could be some crap in the bottom of the buffer tube.
It has happened.

The buffer tube could be out of spec and not deep enough.
It has happened....Chicom part.

The buffer could be out of spec.
(too long)

So, I'm pretty sure I'm not short-stroking the bolt when I charge the rifle, I can't say I'm 100% certain, but I was feeling for the end of the pull before I released the bolt. I can say with certainty that the bolt was definitely behind the magazine because I was looking in the chamber as I was pulling the handle back, and did that several times. In addition, in order to lock the bolt back, I had to pull it completely to the rear, and the feel of that felt the same as my other pulls. The bolt just wasn't grabbing a round. Lock the bolt back first, then release it, and everything works fine.

What I didn't try was putting an empty mag in the well on a closed bolt and seeing if that would cause the bolt to lock back when I pulled the handle. One person online suggested that on another site when I did little Google search on the subject. I don't have any dummy .223 rounds at home (probably need to get a few) so I can't really test my pulls/loading again until I get to the range as I really don't want to chamber live rounds at home if I can avoid it.

Since several have mentioned the buffer, I can certainly consider that to be a potential contributor. I don't have a spare buffer on hand at the moment, so swapping it will have to wait. I'll try going through my process again, maybe adjusting the mag catch as suggested above, and see if I can find any other solution. If none of that works, I'll get another buffer tube and try that out.

 

[jbett98]

Look at the buffer detent retainer and see if it's up too high.

 

[DirectDrive]

Lock the bolt back first, then release it, and everything works fine.

There might be a clue here.

1) With the bolt closed, insert a loaded mag

2) Pull the bolt back and observe how the top round in the mag "presents"

3) Everything look normal ?

 

[etrain16]

There might be a clue here.

1) With the bolt closed, insert a loaded mag

2) Pull the bolt back and observe how the top round in the mag "presents"

3) Everything look normal ?

I'll make a note of this next time I'm at the range, or if I happen to pick up a few dummy rounds in the meantime.

 

[Misteramax]

Etrain, what brand is your carrier?

So...if you could take your rifle to someone for inspection that would be the best. If you were in the valley I could just look at it for you.

If the rifle cycles when firing it's not the extension tube, spring, or buffer. If the buffer retainer is out of spec, it's not going to stop the rifle from working. Depending on the hole location, the bad out of spec is to far back, causing a gap between the buffer face and rear of the carrier causing the buffer to get chewed up and slam into the retainer causing damage to it. But this isn't your issue.

If your pulling your charging handle all the way back, not riding it and letting go, your areas you need to look at are mag catch, catch location, and the underside of the carrier.

We're looking at two things. The location of the mag latching point and I have seen off brand carriers use funky geometry when made or be so badly made it wasn't worth the savings. There isn't much to diagnose on a di ar.

Are you getting gouges in your hammer? Odd question, I know.

 

[DirectDrive]

Etrain, what brand is your carrier?

So...if you could take your rifle to someone for inspection that would be the best. If you were in the valley I could just look at it for you.

If the rifle cycles when firing it's not the extension tube, spring, or buffer. If the buffer retainer is out of spec, it's not going to stop the rifle from working. Depending on the hole location, the bad out of spec is to far back, causing a gap between the buffer face and rear of the carrier causing the buffer to get chewed up and slam into the retainer causing damage to it. But this isn't your issue.

If your pulling your charging handle all the way back, not riding it and letting go, your areas you need to look at are mag catch, catch location, and the underside of the carrier.

We're looking at two things. The location of the mag latching point and I have seen off brand carriers use funky geometry when made or be so badly made it wasn't worth the savings. There isn't much to diagnose on a di ar.

Are you getting gouges in your hammer? Odd question, I know.

Some good logic right there.

 

[Misteramax]

Some good logic right there.

Thanks. I used to work for a manufacturer. I have seen what a saturated ar market does. It gives you sub standard parts. Or parts, such as a carrier, that go away from legacy dimensions without knowing why an older carrier design is the way it is.

As far as etrains rifle, I would check his charging handle, the area milled for it, the gas tube/key mating, and see if that carrier isn't out of spec. After that if all those are fine, it's pretty well down to the mag catch.

 

[etrain16]

Thanks. I used to work for a manufacturer. I have seen what a saturated ar market does. It gives you sub standard parts. Or parts, such as a carrier, that go away from legacy dimensions without knowing why an older carrier design is the way it is.

As far as etrains rifle, I would check his charging handle, the area milled for it, the gas tube/key mating, and see if that carrier isn't out of spec. After that if all those are fine, it's pretty well down to the mag catch.

Regarding the BCG, it came with the upper, which I got in a part trade a year or so ago, and he didn't identify the mfg of that part. I noted in my OP that I have mated this upper with another lower previously and didn't experience this issue. For that reason, I've been thinking along the lines of the lower being a more likely concern. I need to try mating it to another lower and see if the problem follows the upper or stays with the lower. Same thing is to mount the potentially questionable lower with another upper to see if the issue appears to follow the lower. Basic troubleshooting I would use on electrical issues - try to follow the problem.

I think I'll try that first to see if the problem moves with either the lower or the upper, or if the problem only occurrs when these particular parts are mated.

That said, if it makes sense to take a closer look at the bolt, including taking some dimensions, etc., I can certainly do that.

 

[Misteramax]

Regarding the BCG, it came with the upper, which I got in a part trade a year or so ago, and he didn't identify the mfg of that part. I noted in my OP that I have mated this upper with another lower previously and didn't experience this issue. For that reason, I've been thinking along the lines of the lower being a more likely concern. I need to try mating it to another lower and see if the problem follows the upper or stays with the lower. Same thing is to mount the potentially questionable lower with another upper to see if the issue appears to follow the lower. Basic troubleshooting I would use on electrical issues - try to follow the problem.

I think I'll try that first to see if the problem moves with either the lower or the upper, or if the problem only occurrs when these particular parts are mated.

That said, if it makes sense to take a closer look at the bolt, including taking some dimensions, etc., I can certainly do that.

I was born to lead not to read. (Simpsons movie quote) I missed that part in your op. Lol.

Yeah I'd be suspicious of that mag catch area. These things happen...I have seen lowers with hole locations out of spec.

 

[etrain16]

I was born to lead not to read. (Simpsons movie quote) I missed that part in your op. Lol.

Yeah I'd be suspicious of that mag catch area. These things happen...I have seen lowers with hole locations out of spec.

So, with your background, would it be odd that if the mag catch is out of spec that it would operate fine during normal shooting or from a locked back bolt, but not when charging from a closed bolt?

 

[Misteramax]

So, with your background, would it be odd that if the mag catch is out of spec that it would operate fine during normal shooting or from a locked back bolt, but not when charging from a closed bolt?

It's possible. I really think someone should just look at it. I'm going back and forth in my head thinking of things, saying that makes sense but contradicting myself on others.

 

[titsonritz]

If the rifle cycles when firing it's not the extension tube, spring, or buffer. If the buffer retainer is out of spec, it's not going to stop the rifle from working. Depending on the hole location, the bad out of spec is to far back, causing a gap between the buffer face and rear of the carrier causing the buffer to get chewed up and slam into the retainer causing damage to it. But this isn't your issue.

It is pretty pathetic when "Band-Aid parts" are made to fix substandard manufacturing processes.
AR Platform Offset Buffer Retainer

If your pulling your charging handle all the way back, not riding it and letting go, your areas you need to look at are mag catch, catch location, and the underside of the carrier.

We're looking at two things. The location of the mag latching point and I have seen off brand carriers use funky geometry when made or be so badly made it wasn't worth the savings. There isn't much to diagnose on a di ar.

Are you getting gouges in your hammer? Odd question, I know.

I'm going with an out of spec lower at the mag catch location. The pressure the rounds on the closed bolt is just enough to gum up the works.

Thanks. I used to work for a manufacturer. I have seen what a saturated ar market does. It gives you sub standard parts. Or parts, such as a carrier, that go away from legacy dimensions without knowing why an older carrier design is the way it is.

But all parts are the same, you're just paying for a name.

 

[Misteramax]

It is pretty pathetic when "Band-Aid parts" are made to fix substandard manufacturing processes.
AR Platform Offset Buffer Retainer


I'm going with an out of spec lower at the mag catch location. The pressure the rounds on the closed bolt is just enough to gum up the works.



But all parts are the same, you're just paying for a name.

Precisely. I was thinking in condition one basically, the pressure downwards on the rounds is just enough resistance to make it a crap shoot.

 

[clearconscience]

So any news?

 

[eldbillbo]

without reading through all these replies and some of them are on the nose for possibilities but when I read that this upper worked on another lower. The first thing I would look at is do you have the right buffer spring in it. make sure its a carbine spring in a carbine buffer tube rifle springs have more coils. you may also have a tired spring just because it works fine while shooting does not mean its not tired.

But It reminded of when I came across this issue once and I know it's going to sound odd to some but after you troubleshoot all other possibilities this happened to me with an out of spec lower but what happened was the hammer pushed the carrier up just enough that it could not pick up a round when manually charging it, however, worked fine on its own. My guess is the bounce on the return from being fired was enough to push the hammer down enough and pick up the next round vs manually pulling it back I polished the corner of hammer rounding tips that the carrier runs on (mil-spec hammer not the rounded dpms style) carrier and it ran smoothly after that.

 

[etrain16]

So any news?

Not yet. I won't get back to the range for a while, but I ordered some dummy rounds so I could mess around with the cycling at home, slowly, and have some time to take a closer look at things before I start altering anything. I'm going to try swapping the upper to another lower and try swapping the lower to another upper, just to see if the problem follows one or the other - if it does, at least I know which item to start with. It could also be that it's a problem specific only to this upper and this lower when mated. I'll do some investigating once those dummy rounds arrive - I don't want to mess with live rounds cycling in my AR at home.

 

[etrain16]

without reading through all these replies and some of them are on the nose for possibilities but when I read that this upper worked on another lower. The first thing I would look at is do you have the right buffer spring in it. make sure its a carbine spring in a carbine buffer tube rifle springs have more coils. you may also have a tired spring just because it works fine while shooting does not mean its not tired.

But It reminded of when I came across this issue once and I know it's going to sound odd to some but after you troubleshoot all other possibilities this happened to me with an out of spec lower but what happened was the hammer pushed the carrier up just enough that it could not pick up a round when manually charging it, however, worked fine on its own. My guess is the bounce on the return from being fired was enough to push the hammer down enough and pick up the next round vs manually pulling it back I polished the corner of hammer rounding tips that the carrier runs on (mil-spec hammer not the rounded dpms style) carrier and it ran smoothly after that.

Interesting suggestion, I'll add that to the list of things to check. As I just noted in the post above this one, I'm going to try swapping the upper and lower with some other uppers/lowers and see if the problem follows either one. That should help eliminate some of the possible issues. As for the buffer tube and spring, they are brand new, but I wouldn't put it past the possibility that something is out of spec. I don't have another buffer tube on hand to try at the moment unless I pull one from a different lower, so I'm going to hold on that until I've exhausted the other options.

 

[etrain16]

Done with outside stuff for today, just getting too warm, and finally got some dummy rounds for the AR to see if I can figure out what's going on.

So, I loaded them in a mag, and tried it out. Once again, I inserted the mag and drew the bolt back and let it go forward. Again - no round picked up. Drew the bolt back again and tried a 2nd time, still nothing. On the third attempt, I kept the bolt back and let it go forward slowly, definitely not stripping a round. So, tried it again, then pushed up on the magazine - there was definitely room for it to move up, maybe 1/16", then let the bolt go - bingo, picked up a round. Pulled the bolt back again and, no problem, picked up the round. Tried it over and over again, and it loaded fine. Re-insert the mag on the closed bolt, and the same issue again.

It certainly appears to be related to the bolt catch. Not sure the best way to approach this. I can remove the bolt catch and re-install it, but not sure if that will fix the issue. I think I've got the bolt catch threaded to the proper depth, but I can certainly try installing it again and see if that helps.

It would appear the buffer, etc., are not the problem, just the mag seating just a bit too low when inserted on a closed bolt. Any other thoughts on how to address this?

 

[Misteramax]

Done with outside stuff for today, just getting too warm, and finally got some dummy rounds for the AR to see if I can figure out what's going on.

So, I loaded them in a mag, and tried it out. Once again, I inserted the mag and drew the bolt back and let it go forward. Again - no round picked up. Drew the bolt back again and tried a 2nd time, still nothing. On the third attempt, I kept the bolt back and let it go forward slowly, definitely not stripping a round. So, tried it again, then pushed up on the magazine - there was definitely room for it to move up, maybe 1/16", then let the bolt go - bingo, picked up a round. Pulled the bolt back again and, no problem, picked up the round. Tried it over and over again, and it loaded fine. Re-insert the mag on the closed bolt, and the same issue again.

It certainly appears to be related to the bolt catch. Not sure the best way to approach this. I can remove the bolt catch and re-install it, but not sure if that will fix the issue. I think I've got the bolt catch threaded to the proper depth, but I can certainly try installing it again and see if that helps.

It would appear the buffer, etc., are not the problem, just the mag seating just a bit too low when inserted on a closed bolt. Any other thoughts on how to address this?

Remind me...is this an Anderson lower?