MR1 jamming constantly with LAR-15 mags

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WolfeMan

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I bought a 10 pack of the Canada Ammo orange follower LAR-15 mags, and every single one will jam, multiple times even. It's getting to the point where I'm only shooting 7 or 8 out of the 10 rounds and throwing the rest on the ground because the bullet is squashed right into the case. This hasn't ever happened with the factory magazine, only the RRA LAR-15 mags. Is there a different follower to install? Maybe take the file to them? I don't think this matters, but I'm putting .223 through it and the follower's marked 5.56. Any input is appreciated.
 
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Hollowpoint ammo caused constant jams in my MR1. Spire point never jammed once. This was with LAR mags. Describe the jam a little better, obviously the bullets are getting hung up and pushed back into the casing but where are they hitting? The mag or the chrome ring in the barrel extension?
 
Where is it jamming - or better said, is it jamming such that the round gets caught with the case on the front edge of the mag? If that's sounds like the sort of thing, get a flat file and file the front edge of the mag down a little and try to bevel the inside edge of the front if you can. I have 6 LAR mags that were jamming - little file time and they work perfect now.
 
Unfortunately, the orange follow IS the upgrade follower you'd instal to upgrade a nuisance mag. It's a damn near exact replica of the famous magpul upgrade followers.

For jams like that, I keep one of those kinetic bullet puller hammers in my range bag. That way when I get that kind of jam and it sets back a puller, I can use the hammer to tap it back out to the proper seat length and still be able to use it.
 
55 gr. FMJ, factory loads. It appears as though the bullets are ramming into the beveled lip where the chamber meets the barrel. Unfortunately my room mate is away for a month and his AR is locked away in his safe to prevent further experimentation. But seeing as all 10 are afflicted, it can't just be a freak accident. Pinned USGI mags also work flawlessly. When it jams the nose of the bullet will be against the top of the beveled edge, the bolt is against the case about half-way up and it sits at about a 45 degree agle to the barrel. If I was a bit more forum savvy I'd have the pictures I took posted by now.
 
One final thought for the night - in a Youtube review of a 60 round magazine, the poster mentioned that it was jamming and he suspected the springs were too strong and were pushing too much against the bolt. Any thoughts?
 
WolfeMan said:
One final thought for the night - in a Youtube review of a 60 round magazine, the poster mentioned that it was jamming and he suspected the springs were too strong and were pushing too much against the bolt. Any thoughts?
Click to expand...

Try loading one or two rounds in the mag to check for function. Work your way up towards full capacity. If it works until you get to eight or nine rounds, you may be on to something.
 
WolfeMan said:
One final thought for the night - in a Youtube review of a 60 round magazine, the poster mentioned that it was jamming and he suspected the springs were too strong and were pushing too much against the bolt. Any thoughts?
Click to expand...

Funny you should mention that. Do you find the 10th round hard to insert ?
I have one of those angled bottom Black/Orange mags, and the 10th round is tight.
Try the method Stevo mentioned. If indeed it's a tightness problem, them mag would probably work reliably will less rounds loaded.
 
The 10th round is very tight on all of mine. I engraved numbers on them so I cam keep track of what I've done to which mags. Hopefully with some experimentation I can get this figured out.

I think in groups of 2 I'll try filing the lip of the mag, switch the position of the follower spring, load up to 8, load up to 6 and that will leave me 2 for a baseline.
 
Hmm, that almost sounds <gasp> scientific!! Where will the emotion come from that has to be about ready to pounce any second now???


;)
Good plan.
 
Ok listen.
You have to polish those mags a bit for smoothness. Get a dremel with a grinding stone.
Insert 2-3 ammo in the mag, and push with your finger. The rounds should just "get pushed out gently". Now, you will notice that the round 1- catches the side indents, and 2- hits the front of the mag instead of leaving the mag.
Grind the inner side indents where it catches, and grind the front of the mag. Then grind the side lips just a bit to make those smooth.
Had 6 defective mags(all ftf, crush bullets, etc) once polished a bit they are now 100% reliable, all the time, every time, 2 diff rifles. Took maybe 2 hours to polish 6.

The last round is tight with a new mag, it will get okay with time. Load mags and keep them loaded for a while, spring will slack up.
 
Thanks for the tip. I'll make sure to give that a try. So far filing the front lip of the magazine has made an improvement, but I've only cycled rounds manually, I haven't had the chance to get any range time in. But like I said, they're no longer jamming when cycled manually so that's something.
 
Interesting. I finally got my DPMs Oracle out to the range over the weekend and used all 10 of my LAR mags. I actually found both the ones that I had filed and the ones without cycled with no issues. (4 filed, 6 as rec'd - untouched). Damm - needed 100 rounds to do that little experiment ;)
 
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