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Posted: 4/25/2011 3:39:54 AM EDT
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... When using magazine as a "mono-pod". This normal? Any way to fix this easily? Please don't just post "don't put weight on the magazine" as a fix.  |
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Tightening the mag catch will do very little.
I would be more inclined to ask if it is in spec, as is the mag? I vote you have a tight upper to lower fit, and that is allowing the slight upward movement of the magazine to press against the BC, thus retarding its movement. |
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I would think that this issue would be more directly related to the size of the hole in the magazine (that the catch engages) than the tightness/looseness of the catch itself. The larger the hole the more vertical play the magizine will exhibit.
Tightening it a bit is easy though so you could always try and if it doesn't help you ca back it out by the same amount of rotations that you tightened it by. Posted Via AR15.Com Mobile |
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Quoted: Tightening the mag catch will do very little. I would be more inclined to ask if it is in spec, as is the mag? I vote you have a tight upper to lower fit, and that is allowing the slight upward movement of the magazine to press against the BC, thus retarding its movement. Happened with multiple PMAGs that work great if you don't use the mag as a mono-pod. The upper and lower are a bit tight, but I haven't done anything to increase that tightness, just how it came. Spike's lower with lower parts and a complete BCM upper (and BCG). Also, wouldn't it have cycling issues if it was dragging on the bottom of the carrier also? |
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Quoted: I would think that this issue would be more directly related to the size of the hole in the magazine (that the catch engages) than the tightness/looseness of the catch itself. The larger the hole the more vertical play the magizine will exhibit. Tightening it a bit is easy though so you could always try and if it doesn't help you ca back it out by the same amount of rotations that you tightened it by. Posted Via AR15.Com Mobile Yeah, I think I'm gonna try tightening it one turn and then load a bunch of magazines with 1 round, shoot each one offhand and see if it locks back... Then shoot each one sitting at the bench, using the mag as a mono-pod and see if it locks back. |
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I would think that this issue would be more directly related to the size of the hole in the magazine (that the catch engages) than the tightness/looseness of the catch itself. The larger the hole the more vertical play the magizine will exhibit. Tightening it a bit is easy though so you could always try and if it doesn't help you ca back it out by the same amount of rotations that you tightened it by. Posted Via AR15.Com Mobile Yeah, I think I'm gonna try tightening it one turn and then load a bunch of magazines with 1 round, shoot each one offhand and see if it locks back... Then shoot each one sitting at the bench, using the mag as a mono-pod and see if it locks back. Again, I think you guys are assuming the mag catch is some kind of adjustable "clamp" that positively locates the magazine. In fact, the size /shape of the magwell, and the magazine itself, makes much more difference on the 'tightness' of the locked magazine. Most of the mag catches Ive seen and installed/adjusted have a lot of play that will allow more movement in a loose fitting magazine, and not so much in a tight fitting magazine. The bottom line is, although you do not want to hear it, I think you should not use the mag for a monopod. Ive never had good luck doing it, as even if vertical play in the mag system is nill, forward/aft rocking still puts a certain pressure on the BC group, pressure that is not there during 'normal' firing. I realize under optimal conditions pressure on the mag makes no difference, but everyone should be realistic, you are dealing with tolerances on SO MANY parts in a functioning rifle, there is no way to be 100% sure external pressure will not affect anything. When you dont rely on the gun to save your life, put pressure anyhow you want. I like to shoot like every shot is improving me/my equipment some how. I like to think by avoiding things like pressing on the bottom of the mag, I will avoid it ever causing me a problem should I actually need the rifle. |
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To be fair, it isn't causing any malfunctions, just not locking the bolt back. We shot over 400 rounds yesterday all with using the mag as a mono-pod with no issues besides this. At the EAG Carbine 2 class, Mike (aka "Mr. Grumpy") specifically told us that if you can't shoot while resting on the mag, you should replace the mag or get it fixed. I'm trying to get it fixed. Maybe I'll have to deal with it not locking back. I can deal with that, since it isn't causing the weapon to cease working. |
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To be fair, it isn't causing any malfunctions, just not locking the bolt back. We shot over 400 rounds yesterday all with using the mag as a mono-pod with no issues besides this. At the EAG Carbine 2 class, Mike (aka "Mr. Grumpy") specifically told us that if you can't shoot while resting on the mag, you should replace the mag or get it fixed.I'm trying to get it fixed. Maybe I'll have to deal with it not locking back. I can deal with that, since it isn't causing the weapon to cease working. I just dont see how you can issue a blanket statement like this without knowing: Build/tolerances of rifle in question Build/tolerances of BCG in question Build/tolerances/wear of magazine in question Seems like so many variables to throw out the old "Either it works like this or its all junk" line. Not discounting his experiences, but surely you get what Im saying. To get back on track to you specifically trying to solve the problem, how about switching out the BCG and see if she works? Just load one round, and test it. Test with an aluminum mag as well. Maybe try a HK mag or one of the other steel ones. |
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On another note... Should the gas tube inside the upper receiver have an even "gas staining" all around the tube? Because mine is visibly dark significantly far down one side of the tube but not at all on other sides. I'm wondering if I might possibly have a gas leak. |
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So, I did some testing tonight... 3 Magpul PMAGS (2 with new grey followers, one with 1st gen black follower), 2 USGI D&H mags (with magpul grey followers). On ALL three Magpul PMAGS, the bolt does not lock back when manually cycling the bolt with the charging handle if I apply either direct downward force or rearward force (towards the buttstock) on the magazine. The follower stays down in the magazine just enough that it will not trip the bolt catch. Letting go of the charging handle will allow the bolt carrier to close entirely into battery. If I lift the gun off "the deck" and no force is applied, the follower immediately goes all the way up and trips the bolt catch. If I let go of the charging handle, the bolt is locked back. This does NOT happen with the Magpul PMAGs if I apply forward force (towards the muzzle) on the magazine, only when pushing directly downwards or backwards (to pull it into my shoulder). On both of my USGI mags, the problem does not occur regardless of how much force I exert on the magazine. When I manually cycle the bolt carrier with the charging handle, it always locks back even if I put most of my body weight onto the magazine. Well, it definitely is not a gas system issue. I'm not sure what is causing the follower to get stuck in the PMAGs. It just will not go entirely up. It does, however, rise enough to feed new rounds as it didn't cause a single failure to feed when doing it with live ammo. Any new thoughts? |
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Quoted: ...Any new thoughts? FWIW Manual operation means next-to-nothing when trying to solve problems like this. It is not even close to what happens when a round is fired. I had a recent problem of failure to feed and failure to lock back. Manual operation of the BCG never replicated the problem and it always fed and locked back. Actual firing saw the problem happen again. |
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...Any new thoughts? FWIW Manual operation means next-to-nothing when trying to solve problems like this. It is not even close to what happens when a round is fired. I had a recent problem of failure to feed and failure to lock back. Manual operation of the BCG never replicated the problem and it always fed and locked back. Actual firing saw the problem happen again. +1 manual op of the system shows nothing more than 'potential' of a working system |
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Quoted: Quoted: Quoted: ...Any new thoughts? FWIW Manual operation means next-to-nothing when trying to solve problems like this. It is not even close to what happens when a round is fired. I had a recent problem of failure to feed and failure to lock back. Manual operation of the BCG never replicated the problem and it always fed and locked back. Actual firing saw the problem happen again. +1 manual op of the system shows nothing more than 'potential' of a working system So if the problem is still occuring... It means nothing? I would say it means a lot. It means that even if my gas system were operating at absolute 100% efficiency (which I'm sure it isn't), there would still be a problem with these magazines and putting weight on them. I left a VM with Magpul, we'll see what they say or if they can provide any help at all. I may want to contact Spike's also if the Magwell is "out of spec." Looking into the magazine from the ejection port, with the bolt carrier pulled back and pressure on the mag shows that the follower is not engaging the bolt catch because the follower is stuck in the magazine. I think this gives a good starting point for sure, and eliminates other possiblities as the cause since you said yourself it imitates the system in it's "ideal" form. I never had failures to feed with actual operation, only lock back and only when putting weight on the magazine. Manual operation did the exact same thing. It sounds like you either had a bad magazine or you had a gas system issue. |
| I fixed this problem with my Pmags yesterday. Look at the back of the mag, at the top. There's a semi-circular cutout. That cutout should be square on the right side, not semi-circular. The excess material there will rub against the bolt catch and not allow the follower up all the way. Just square that up with the horizontal section of the mag beneath the excess. Dremel took 30 seconds to fix. I can post pics if really necessary, but I think you'll see what I mean. |
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Quoted: I fixed this problem with my Pmags yesterday. Look at the back of the mag, at the top. There's a semi-circular cutout. That cutout should be square on the right side, not semi-circular. The excess material there will rub against the bolt catch and not allow the follower up all the way. Just square that up with the horizontal section of the mag beneath the excess. Dremel took 30 seconds to fix. I can post pics if really necessary, but I think you'll see what I mean. Pics please, I'll fix it up on mine when I get a chance... Although I don't have a dremel. |
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Quoted: I hope it does but it meant nothing in mine. Good Luck ! Quoted: So if the problem is still occuring... It means nothing? Quoted: +1Quoted: ...Any new thoughts? FWIW Manual operation means next-to-nothing when trying to solve problems like this. It is not even close to what happens when a round is fired. I had a recent problem of failure to feed and failure to lock back. Manual operation of the BCG never replicated the problem and it always fed and locked back. Actual firing saw the problem happen again. manual op of the system shows nothing more than 'potential' of a working system I would say it means a lot. ...  |
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Here we go. These pictures suck but hopefully in conjunction with the explanation I posted above, it should make sense. http://i1223.photobucket.com/albums/dd519/generalpurpose87/Other/Pmag1.jpg http://i1223.photobucket.com/albums/dd519/generalpurpose87/Other/Pmag2.jpg Is there a sasquatch in there>?
Never had a problem with my pmags. I do notice some fit a little differently than others, but mine are from a wide age range. |
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Here we go. These pictures suck but hopefully in conjunction with the explanation I posted above, it should make sense. http://i1223.photobucket.com/albums/dd519/generalpurpose87/Other/Pmag1.jpg http://i1223.photobucket.com/albums/dd519/generalpurpose87/Other/Pmag2.jpg Is there a sasquatch in there>?
Never had a problem with my pmags. I do notice some fit a little differently than others, but mine are from a wide age range. Maybe there is. In the last pictures I posted (of my SBR), someone saw Jesus in my fence.
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Hey guys. Just wanted to let you know that the PMAG modification did indeed work with ALL of my PMAGs from generation 1 to what I think is the newest generation. All I had to do was shear off most of the top of that small polymer extension that GeneralPurpose mentioned. I didn't even need to use a dremel, just used a pair of wire snips. Came right off with two snips per magazine. Modified them all in about 10 minutes and tested each one. Even with my entire body weight on it, still locked back every time with manual cycling. Now I know that if it doesn't lock back it's a gas system problem, not a mag problem. Thanks GeneralPurpose and everyone else for your help. Much appreciated! |
Hopefully Magpul will address that flaw on their next revision of the Pmags (whenever that may be).
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