magazine (or????) issue?

Status
Not open for further replies.

x_wrench

Member
Joined
Oct 25, 2010
Messages
906
Location
michigan
Hi, I am posting today to get an idea of what might be causing an issue I am having with my AR-15. I have two magazines (I KNOW, I NEED MORE!) and this happens in both of them. If the top cartridges is on the right (ejection port) side, the bolt slides over the cartridge and jams about 1/2 way up the side of the cartridge, most of the time making a small dent in it. if the cartridge is on the left (back) side, it loads and fires like a champ, never having an issue. Once the rifle starts shooting, there never seems to be a problem. I don't know if it's a magazine issue, or something with the feed ramps, or bolt face. And I really don't know where to start looking. any ideas?
 
My first initial guess is maybe you are loading the magazine too full. A full or 1 over full magazine can cause feeding issues. Load 28, not 30.
 
Some magazines, combined with some rifles don't like to be fully loaded. Try inserting the mag with the action locked back. Then press the bolt release. If you insert a fully loaded mag with the bolt closed sometimes this happens. Or download by 1 or 2 rounds. Trying a different brand of magazine might allow you to fully load. You just have to know your gear
 
Hmm, paging @Varminterror

If this is an "M4" style barrel, there's meant to be some cuts to guide rounds into the chamber
=https%3A%2F%2Fwww.brownells.co.uk%2FWebRoot%2FMediaDefinition%2Fuserdocs%2Fskus%2Fl_100004728_2.jpg
You might want to lock the bolt back and eyeball how the rounds line up to the barrel end.

Since it's not magazine dependent, I'd look to the barrel end, then to the bolt profile where it strips rounds.

Question: Is there a difference between running the bolt "by hand" versus by firing? In other words, if you pull back the charging handle manually, can you replicated the uh-oh? Or is it only while firing?
 
Is this happening only on the first round loaded, or all right side positions in the magazine?

Missing rounds on the right side is often a factor of mags not being held tightly in the well by the mag catch. Is your mag catch bolt flush (slightly proud) of the mag button face? Flipping the mag button top to bottom may add enough tension to better hold the mag in place. The troubleshooting here - the mag catch is on the left side, so it’s “fixed” a little higher on that side, even when not held tightly enough. But the right side is able to sag further down as the mag tilts slightly due to insufficient support.

Holding the rifle by the magwell, and putting rearward (and slightly lateral) pressure on the mag can do the same thing, levering the mag against the mag catch. So how you’re supporting the rifle may cause this same malfunction.

Does your rifle have rifle feed ramps, or M4? M4 ramps certainly help in guiding rounds into the chamber, especially longer rounds with heavier bullets. Polishing the feed ramps and “melting” the lugs on the extension can reduce likelihood of failures to feed, so it’s worth doing while you’re troubleshooting anything else - especially when you’re having FTF’s.

Since this is happening with multiple mags, it points away from “mag issues,” which are far and away the most common causes for failures in the AR-15 (or really almost any other repeater). Maybe both of your mags are of the same brand, or the same production run, so maybe the rifle is fine and both of your mags have the same issue, but that’s pretty unlikely. More likely you have a mag tilt issue, and the resistance from the feed ramps is greater than the mis-alignment can overcome.
 
well, my rifle appears to have M4 feed ramps, maybe not quite as large of cut outs as the one pictured above. but I am looking thru the ejection port, not straight on, and I am looking thru cataracts as well. I did get 2 turns on the bolt catch threads. but it didn't make any difference. I decided to take pictures and try to post them. if i can, this might make a difference. one thing i discovered doing this, is in the time frame and style of loading that makes the difference. if i load the magazine into the rifle, then run the bolt, this happens upload_2022-7-10_17-4-37.jpeg

that is what happens, the nose of the round is pointing at a 45 degree angle, and canted upward. so obviously it is not going to be able to feed. and I am sorry, I made a mistake saying that it only did this from the right side. trying to photograph this, I found that it does happen from both sides. just flipped. (when feeding from the left side, the nose of the cartridge is pointing out of the ejection port. this still does not seem like it would be correct. because if I had to clear a malfunction, I would have to drop the magazine every time, then lock the bolt back in order to fix the issue. I purchased a pair of new 30 round magazines, from a different manufacturer, and they did the same thing. so I guess that eliminates the magazines. this rifle was purchased as a kit, and I assembled it from scratch. so there is a 99.9% chance that this is something a first time builder did wrong during assembly. the magazines were purchased complete, meaning nothing in them happened from my tinkering. I just do not understand what could be causing the rounds to kick out like that at slow speed. once I can understand that, I am sure I will be able to fix it.
 
So, if the bolt is closed, then you insert a loaded magzine, then you pull the CH, the top round from either column will jump put of the magazine feed lips?

However, if you have the bolt locked open, then insert a magazine, then release the bolt, it will feed normally?

If both of these conditions are true, Im suspecting something strange going on with the bottom of the bolt carrier.
 
Confirmation that this isn’t a mag issue is great. Proper first step.

Adding tension to the mag catch is another test - two full turns though seems odd. Is the end of the tail of the mag catch bolt flush with the front face of the mag button? That tail is the right length that it should be flush with the mag button face, and then when that button is pressed with a finger to flush with the receiver (or slightly below flush by finger squishing into the receiver), the mag catch doesn’t quite clear the boss on the receiver on the opposite side, but will release the mag well before.

Is this only happening when you ride the charging handle slowly? Many, many AR’s won’t feed well if you ride the charging handle forward slowly, but may feed when released freely. Simply, there’s a gap to be jumped where the round is being released from the mag lips and free to move vertically at the same time it’s being pushed forward - kinda reminds me of the original episodes of that now defunct show Fear Factor where contestants had to jump a gap between two semi-trucks driving 50mph. Full send would make it, but tentative steps would fall… can’t make it slowly…

Also - that picture shows your feed ramps are CHEWING bullets badly. Lots of copper and brass deposits in your extension. I’d polish those ramps and melt those extension lugs, even if it doesn’t completely resolve this issue.

That picture has the bolt locked back, so we can tell you’ve manipulated the rifle after the jam, before the photo, but the jammed cartridge is still pretty far rearward. In your first description, it sounded like common missed pickups, where your bolt is partially stripping the round, the bullet impacting something and stalling, then the bolt skipping over the top of the round. Is that the case? The photo looks like weak mag lips and cartridges releasing too early.

Check this: how much interference do you have between the bolt lugs and cartridges in the mag? You should be able to see the bolt lugs hanging deep into the mags to grab the cartridges. Another way to check this - pull your mag catch out of the rifle, close your bolt, and insert a mag, pressing it up against the bottom of the bolt carrier. Looking through the mag catch slot in the receiver, you shouldn’t see the bottom edge of the mag catch cut on the mag, and should either see alignment or should see just a razor hair of the top edge of the mag cut. If the bottom of the cut is visible and the top edge is not, then you know the mags are sitting too low in the receiver, allowing the bolt to skip over your rims.
 
i really appreciate your help! but I think, this upload_2022-7-10_20-49-29.jpeg is the root cause. this round sticking up at a 45 degree angle cocked sideways as well, allows this,

upload_2022-7-10_20-53-21.jpeg

when I hit the bolt release. I am NOT riding the bolt back slow. this is the condition that I am having this issue. 1) I push a loaded magazine into the weapon with the bolt closed, 2) I pull the charging handle all the way back, 3) I let go of the charge handle, and 4, the gun jams. //// I can make the gun operate just fine, by pulling the charging handle all the way back, while holding the charging handle, I then lock the bolt release. then I insert a loaded magazine, then press the bolt release button. the round goes into battery just fine. but it SHOULD (at least in my mind it should) go into battery both ways, unfortunately, my rifle jams every time I do it the first way. ///@%%!?? I THINK I JUST CAME UP WITH A CLUE. THE RIFLE JAMS EVERY TIME THE BOLT TRAVEL BACKWARDS ACROSS THE SHELLS BEFORE THE BOLT GOES FORWARD. REGUARDLESS OF WHETHER I LET GO OF THE CHARGE HANDLE, OR I PRESS THE BOLT CATCH. IF THE BOLT TRAVELS SLOWLY BACKWARDS ACROSS THEM, THE SHELLS COME OUT FORWARD WHEN THE BOLT GOES FORWARD. WHY, IS THE QUESTION.///// I suspect this is happening so fast when the gun is firing, it does not have a chance for the bullet to get cocked up and to the side. the gun runs fine. either slow and deliberate fire, or fast as I can pull the trigger. by the way, I turned the mag catch another 2 turns to get the threaded end to just protrude a little bit. I think i could turn it 1 or two turns more, but I don't understand what this is doing, except putting extra tension on the spring. the magazines do not drop (when firing), and they come out when I push the mag release. so ???? oh, the feed ramps may not be as bad as you think. when I first built this gun (around Christmas time) I made up 5 dummy rounds. I drilled holes right thru them, and they have no primers, and the bullets have been crimped in place. these dummy rounds have been cycled thru this gun hundreds of times. both trying to fix this issue, and a few others, that were not as tough as this. no, the first picture (on the first photo ( last post) i did not ride the bolt forward. i pressed the bolt release just like in this set of photos. I don't think the mag lips are deformed in either of these photos. they are stainless steel, and this has been happening on and off since I built it. and the new mags that I just purchased do the exact same thing. I say on and off because there have been other issues, which I have been able to fix on my own. they really were pretty easy, mostly caused by my ignorance of this platform. I have been shooting for 55 years, and this is my first semi auto rifle. I have shot several over the years, but this is the first owning one. and the first shots on this platform was on this gun. //// ok, I think the last test, well, actually 2 tests. removing the mag catch, it looked almost flush with the bolt closed with me pushing up on the magazine, and looking at the bolt "purchase" on the casing, it is almost a full lug of engagement on a shell casing when the bolt touches the base of the case, so I think there is plenty of contact. ////////////// I just had a thought, if the magazine springs were installed backwards, could this cause this problem? both of the original magazines were purchased at the same time, most likely made at the same time. it wouldn't be the first time a new hire had messed up a small lot of something. and the way stuff fly's off the shelf these days, it would not be far fetched that they went out the door before somebody noticed.
 
Are you saying these rounds are popping up from the magazine BEFORE the bolt moves forward? Certainly if your rounds are jumping out of the mag before the bolt tries to close, you WILL get failures to feed. That absolutely shouldn’t be happening. For that to happen with 4 mags of 2 different brands is shocking.
 
Yes, that (cargtridge popping up before the bolt goes forward)( it actually happens when the bolt just clears the round going backwards) is exactly what is happening. and I have no clue why.

and yes, this IS a home built gun. and it was my first. I have been tinkering with guns for the last 20 years or so. most of them are not terribly complicated. the only thing that I "farmed out" was a trigger job to a gunsmith with a really good reputation because I could not see exactly how things went back together (on an H&R handi-rifle) . the only things that were "pre assembled" was the magazines, and the barrel extension to the barrel. and I take all responsibility for what ever is going on. I just have no clue what that is.
 
Yes, that (cargtridge popping up before the bolt goes forward)( it actually happens when the bolt just clears the round going backwards) is exactly what is happening.

Given this, nothing else matters.

The only way this can happen - other than bad bad mags releasing the rounds too easily - would be something snagging the rim as the carrier is moving rearward. This CAN happen if the rounds are tilting down at the front in the mag, follower tilt, but it’s almost always a problem with mag lips. Very odd that 4 of your mags, 2 brands, are doing the same thing.

With this info, I’d open the bolt slowly over the top of the rounds and watch the magazine until the bolt head clears the port so we can see the rounds in the mag, then watch the rounds - watch for when either the mag or rounds move, that will indicate the position on the carrier where the contact is happening. It HAS to be something peeling backward on the case rims, otherwise it’s the carrier grooves doing something bad to the mag lips.
 
Clean your mags well with Ballistol; work the spring and follower up and down a lot while doing so. If you can, borrow someone else's mags that you know run well and try them in your rifle. In my experience this malfunction is almost always a magazine issue, except when its a feed ramp issue. Are your mags new or have they worked well in the past with a different rifle?

If it is happening on just once side of the mags it very well could be a feed ramp issue as others have indicated. Can you get us a clear picture of the feed ramps? It looks like this is a 5.56, correct? Other chamberings sometimes have their own unique feeding issues. I know only too well how frustrating feeding issues can become.
 
The entire rig is new. roughly 500 rounds on it. I started shooting it in April of this year. with 2 brand new magazines purchased 30 hours or so ago. whatever is going on, is way before the feed ramps. the top round gets thrown cockeyed as the bolt travels rearward over the cartridges while I am running the charge handle. I have noticed in the many times I have done this since my last post last night, that it does happen less in the brand new magazines than it does in the first set of magazines. so dirt in the magazine may have something to do with it. but it is not the real issue, because it still happens with the brand new mags. i took the BCG out and cleaned it. greasing the bottom of the BC. hoping that less friction might have an effect. but no luck. I am beginning to wonder if there is a sharp edge on the back side of the bolt lugs that are catching the the top round of the magazine, turning it sideways. That will have to wait until tomorrow, as i am headed to bed now.
 
The entire rig is new. roughly 500 rounds on it. I started shooting it in April of this year. with 2 brand new magazines purchased 30 hours or so ago. whatever is going on, is way before the feed ramps. the top round gets thrown cockeyed as the bolt travels rearward over the cartridges while I am running the charge handle. I have noticed in the many times I have done this since my last post last night, that it does happen less in the brand new magazines than it does in the first set of magazines. so dirt in the magazine may have something to do with it. but it is not the real issue, because it still happens with the brand new mags. i took the BCG out and cleaned it. greasing the bottom of the BC. hoping that less friction might have an effect. but no luck. I am beginning to wonder if there is a sharp edge on the back side of the bolt lugs that are catching the the top round of the magazine, turning it sideways. That will have to wait until tomorrow, as i am headed to bed now.
Do you have another bolt or bolt carrier you can swap out to test that theory?
 
If you have a spare bolt carrier try throwing that in. You might have a defective bolt/carrier. I have seen this type of failure before but it was magazine failure and it was only happening on one magazine. That faulty magazine had feed lips spread just a tad too far and it was pushing rounds into the chamber with slight bolt pressure. Because it is happening on 2 magazines of different brands, a faulty magazine is less likely but still possible.
 
@Varminterror is there a possibility that the mag is a skosh too high up?

As in just enough that there's too much friction from the BCG on the top rounds when pulled back slowly, and it's just enough to boink the rounds up?

Where I'm going with the notion is that maybe OP ought try a suitably hard yank on the charging handle, PFC Gorilla style (something I've seen many AR owners loathe to do).

Now if increasing the bolt velocity prevents the issue, then, I'm drawing a blank as to what to do next.

I am curious about the brands of upper and BCG OP used.
 
Well, no, I do not have a 2nd bolt or BCG, but I did take a honing stone to the back edges of the lugs that would make contact with the cartridges. I used a fine stone, for a couple of reasons. the primary one was because those lugs are load carrying lugs, and I certainly did not want to weaken them. anyway, i rounded off all of the sharp edges on those lugs. It did help some, but its not the end all to this issue. so after a while of thinking, I began to wonder if this could be caused by using the same 5 "dummy rounds" that I had made up. no luck there either. so I am out of Ideas.
 
Typically no, this wouldn’t be a consequence of a high magazine. Drag on the carrier is typically the only negative consequence of the a high magazine. In this case, the rounds having extra magazine spring compression would only be relevant for the first round from the mag (an even number, in fairness), but all remaining rounds would have less compression force as the stack depletes than the first round, so that excessive force would only happen for one round. The excessive run at the mag lips shouldn’t matter, they’re designed to NEARLY drag on the carrier, so an extra 10-20 thousandths of run at the lips shouldn’t create this issue - you should be able to put a few rounds in a mag, depress them halfway down with a paint stirrer, and release them, and the lips will catch them with no spray.

So @x_wrench - can you see WHEN the rounds are tilting if you cycle the charging handle slowly to the rear? Can you see any deviations in the mag position as you’re drawing rearward? Out of the rifle, is the inner rail in the bottom of the carrier wider than the gap in the mag lips - is it dragging at the sides when you lay a mag into the carrier as it would be in the rifle?

Where are you located? Let’s see how lucky we are.
 
Status
Not open for further replies.
Back
Top