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Discussion Starter · #1 ·
Hello all

I got my hands on an M a few months ago, and have been generally enjoying it quite a bit, with about 1k rounds down the pipe so far. Recently, however, I've noticed a semi-frequent malfunction. With my 25rnd M118-sized PMAGs, loaded with M80 ball, I get a failure to feed on the last round of the magazine. Whenever this happens, the round doesn't seem to get angled up properly, and ends up being compressed between the bolt and the outside of the chamber, forcing the bullet back into the cartridge case. It doesn't happen with all my mags of this type, and not all the time with the ones that do fail.

My hypothesis is that either this batch of PMAGs has weak springs, or there is some sort of problem with the geometry of the larger internal size of the M118 magazines, in relation to M80. I haven't had this happen while shooting the longer M118 rounds out of these mags, or M80 out of the older-style, grey follower PMAGs.

I've noticed this across all the different brands that I've shot, so I don't think it's ammo-specific, but for posterity:
PPU
PMC
Wolf steel case
Bullets 1st, whose M80 is some weird bimetal bullet loaded in federal brass that I won't be buying again.

All of this has been unsuppressed, through a 16" barrel with type 2 gas at setting 3.

Any and all insight would be appreciated. I'm looking to standardize my magazines. If it turns out that the long PMAGs are the culprit, which I'm fairly convinced that they are, I'm looking at a couple alternatives:

1. I annihilate my bank account by switching to Larue/KAC mags to be able to feed reliably and keep using M118 as my "serious" ammo
2. I look into some 168gr ammunition offerings, which may or may not perform as well as 175gr, but would allow me to use a broader selection of magazines, including the 20rnd PMAGs, which are supposed to have better springs than the 25s.

Thanks in advance!
 

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Hello all

I got my hands on an M a few months ago, and have been generally enjoying it quite a bit, with about 1k rounds down the pipe so far. Recently, however, I've noticed a semi-frequent malfunction. With my 25rnd M118-sized PMAGs, loaded with M80 ball, I get a failure to feed on the last round of the magazine. Whenever this happens, the round doesn't seem to get angled up properly, and ends up being compressed between the bolt and the outside of the chamber, forcing the bullet back into the cartridge case. It doesn't happen with all my mags of this type, and not all the time with the ones that do fail.

My hypothesis is that either this batch of PMAGs has weak springs, or there is some sort of problem with the geometry of the larger internal size of the M118 magazines, in relation to M80. I haven't had this happen while shooting the longer M118 rounds out of these mags, or M80 out of the older-style, grey follower PMAGs.

I've noticed this across all the different brands that I've shot, so I don't think it's ammo-specific, but for posterity:
PPU
PMC
Wolf steel case
Bullets 1st, whose M80 is some weird bimetal bullet loaded in federal brass that I won't be buying again.

All of this has been unsuppressed, through a 16" barrel with type 2 gas at setting 3.

Any and all insight would be appreciated. I'm looking to standardize my magazines. If it turns out that the long PMAGs are the culprit, which I'm fairly convinced that they are, I'm looking at a couple alternatives:

1. I annihilate my bank account by switching to Larue/KAC mags to be able to feed reliably and keep using M118 as my "serious" ammo
2. I look into some 168gr ammunition offerings, which may or may not perform as well as 175gr, but would allow me to use a broader selection of magazines, including the 20rnd PMAGs, which are supposed to have better springs than the 25s.

Thanks in advance!
Sounds like you've already figured it out....if it doesn't happen with other mags, it's the mag.

Have you contacted Magpul?....might be worth it to send the bad ones in and warranty or switch to the other shorter Pmags to see if it fixes the problem. I have both the shorter and longer PMags and they work in both my M's flawlessly and I shoot a mix of mil-surp including M80 and steel case out of my Ms.
 

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Discussion Starter · #3 ·
Sounds like you've already figured it out....if it doesn't happen with other mags, it's the mag.

Have you contacted Magpul?....might be worth it to send the bad ones in and warranty or switch to the other shorter Pmags to see if it fixes the problem. I have both the shorter and longer PMags and they work in both my M's flawlessly and I shoot a mix of mil-surp including M80 and steel case out of my Ms.
I figured as much, just wanted to see if anyone else was having a similar issue. I'll do some more testing across my mags when I have the time/ammo.

If the problems persist, I'll probably switch to metal mags. Since I don't feel like damaging my credit score for LaRue/KAC M118 magazines, do you have any recommendations for 168gr factory match loads?
 

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I figured as much, just wanted to see if anyone else was having a similar issue. I'll do some more testing across my mags when I have the time/ammo.

If the problems persist, I'll probably switch to metal mags. Since I don't feel like damaging my credit score for LaRue/KAC M118 magazines, do you have any recommendations for 168gr factory match loads?
I have a bunch of 20 round Cproducts SS mags that work just fine too....no better than my Pmags though. But, I'm not shooting 168gr ammo much either.
 

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My hypothesis is that either this batch of PMAGs has weak springs, or there is some sort of problem with the geometry of the larger internal size of the M118 magazines, in relation to M80. I haven't had this happen while shooting the longer M118 rounds out of these mags, or M80 out of the older-style, grey follower PMAGs.
Just a diagnostic idea:
Is there a way to assemble the magazine with a shim block under the spring at the bottom of the magazine, to raise the spring pressure on the last round?
Then load four or five rounds in and see if it will accept that last round with the additional pressure.
 

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Discussion Starter · #6 ·
Just a diagnostic idea:
Is there a way to assemble the magazine with a shim block under the spring at the bottom of the magazine, to raise the spring pressure on the last round?
Then load four or five rounds in and see if it will accept that last round with the additional pressure.
I could give that a try. A friend of mine said he was having misfeeds with m118 pmags shooting m80 through his sr25, so I'm pretty convinced that it's just a mag issue at this point.
 

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I can second the duramags, and can confirm they run well in the xcr-m, a dpms ar-10 and a diamondback db-10 ar, all in 308.
 

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Can also say I've had good experiences with e-lander 308 mags,I know others may have had trouble in the past but the couple I've had ran well, asc and c products are hit and miss had about 75% working when I got them and after some tinkering got them all working 100%. lancer are probably the best, but for the money but you can get 2 1/2 duramags for the cost of the lancer.
 

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Discussion Starter · #10 ·
Duramag AR-10 .308/7.62X51 20-Round Stainless Steel Magazine (gunmagwarehouse.com)
$20 each plus shipping. They run 100% in my AR-10. The reviews are great.
Can also say I've had good experiences with e-lander 308 mags,I know others may have had trouble in the past but the couple I've had ran well, asc and c products are hit and miss had about 75% working when I got them and after some tinkering got them all working 100%. lancer are probably the best, but for the money but you can get 2 1/2 duramags for the cost of the lancer.
Thanks for the replies. I was looking at duramags primarily, since I've heard good things about them generally, and they're what Robinson themselves shill. Since a friend of mine told me that the Federal GMM 175gr isn't overly long like m118lr is, I don't see a reason not to make the switch anymore.
 
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