A friend left me with his DPMS AR-10 LR308, which has cycled poorly. Before taking this to a gunsmith, I wondered if this rifle was designed to shoot only ball ammo. My buddy gave me what looked like a cheap ball ammo; it fed 75% of the time and wouldn't feed factory lead tip ammo. He gave me Pro Mags; could that be a problem? I went out and bought a PMAG20 and some higher-quality Ball ammo.
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DPMS AR-10 LR308
- Thread starter Iron Worker
- Start date
My lr-308 runs like at top. Steel DPMS mags or Magpul pmags. The only stoppages I’ve had with it were induced by monkeying with a JP adjustable gas block.
I’ve never shot military ball ammo, but put several flavors of hunting and match ammo through it.
Was the rifle clean? Lubricated?
Promags, as a rule, are hot garbage.
I’ve never shot military ball ammo, but put several flavors of hunting and match ammo through it.
Was the rifle clean? Lubricated?
Promags, as a rule, are hot garbage.
Yes, it has been cleaned and lightly lubricated. I'll take it to the range with the new ammo and PMAG.
I logged into their website. The video greatly simplifies the choice.
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If the problems continue after trying different mags and ammo, you're going to need to provide a lot more info, starting with if it's a factory built DPMS/Panther LR308, or are you describing the platform. A better description of the failure to feed, like bolt over brass, will help.
Knowing the specifics of the components used will also help, especially on a non-factory built firearm. Like the receiver extension length and the weight and length of the buffer would tell you if something like a Sprinco orange is the correct spring.
Then you can get into a standard troubleshooting checklist, like wear items (gas rings, springs), component failure (gas tube, gas key), and all the rest.
Knowing the specifics of the components used will also help, especially on a non-factory built firearm. Like the receiver extension length and the weight and length of the buffer would tell you if something like a Sprinco orange is the correct spring.
Then you can get into a standard troubleshooting checklist, like wear items (gas rings, springs), component failure (gas tube, gas key), and all the rest.
Pro Mags are truly hot crap.
I bought a 30rd Pro Mag for my LFAR, just for poops and giggles ( 10bucks ) ... the mag spring wasn't even strong to push the stack of 30rds - 20rds to the feed lips....
I bought a 30rd Pro Mag for my LFAR, just for poops and giggles ( 10bucks ) ... the mag spring wasn't even strong to push the stack of 30rds - 20rds to the feed lips....
I had one years ago and it was reliable. 95% of what I shot in it were reloads with the 168 Amax and SMK.
Pro Mags are not known for their reliability.
Pro Mags are not known for their reliability.
Bolt over brass. But not all the time. It might have an aftermarket bolt group Looking through the ejection port on the bolt it says JP then in smaller letters LMOS
That is definitely an aftermarket carrier. LMOS is JP’s light weight carrier. While a quality piece, it may or may not be adding to your problems. I’d still start with the mags. Failure to feed could simply be how the mag interfaces with the mag catch.
JP is a top of the line carrier. You have the light weight version. Typically you want an adjustable gas block to properly tune the light weight carrier.
Take out the buffer and look for #'s on it or weigh it. Report back.
Before you pull the buffer do this test. With bolt locked back on bolt catch, grab charge handle and see how much further you can pull bolt back past stop. Should be 1/8 -3/16. If it's more just throw a quarter or 2 in the back of the buffer till clearance is correct.
@Iron Worker - Here is another easy test for bolt over ride issues. For DPMS this should be checked.
Open the upper and slap a p-mag in. That little step/shelf at the back of mag picture below should be damn near level with the top of the lower.
If it's sitting low you'll be chasing your tail trying to get it to function reliably.
There's something like .050 height variation for the mag catch across 3 different lower blueprints for large frame DPMS. The one pictured was in spec, but on the low side. Absolutely nothing would fix the intermittent bolt over-ride. Once the catch was raised to the high side of spec nothing I've tried will make it malfunction. Any ammo, any mag with functional spring it eats it like a wood chipper.
Open the upper and slap a p-mag in. That little step/shelf at the back of mag picture below should be damn near level with the top of the lower.
If it's sitting low you'll be chasing your tail trying to get it to function reliably.
There's something like .050 height variation for the mag catch across 3 different lower blueprints for large frame DPMS. The one pictured was in spec, but on the low side. Absolutely nothing would fix the intermittent bolt over-ride. Once the catch was raised to the high side of spec nothing I've tried will make it malfunction. Any ammo, any mag with functional spring it eats it like a wood chipper.
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Okay, I'm back from the range. The junk magazine was 100% the problem. I shot 40 rounds of Fiocchi Ball ammo, and the rifle functioned flawlessly. Thanks to everyone for responding.
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ProMag is for introducing malfunctions when you want to train how to clear them.
They are excellent tools for that, especially if you slip them into someone else’s magazine pouches or range bag.
They are excellent tools for that, especially if you slip them into someone else’s magazine pouches or range bag.
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