AR 10 DPMS feeding issues

[rpol98]

You sure the spring in the bad mag is good? That would be my concern if the lip tweak was the same on both mags, the spring is the only other variable. Or like you stated, might have "over tweaked" the bad mag. Chances are that the S&B ammo you got is the culprit if the gun ran fine with other make ammo. Worse case, tear down the S&B ammo and re-powder it with known type. Yeah I know thats a s#it show, but what else you gonna do? Good luck.

yeah, the now-worser mag used to perform flawlessly before. it's not worn-out, pretty new as far as mag life-cycles go. i'm pretty sure it's overtweaked, the rounds can be flipped up pretty easily, compared to the tweaked good mag. probably has something to do with the problem.

I did deburr the inside edges of the feed-lips after tweaking.

 

[C-130 Dude]

Couple things I learned after bending the lips...the mag needed to be deburred on the inside edge, as it was making real fine brass hair, cutting it off the cases. Also, it's difficult to get both sides of the stack the same. Got it close, tho.
Also learned that PPU ammo is pretty hot. Just the opposite of what I stated a few posts back. Magneto Speed says it leaves at 2850. And the ejected case pile agrees. They nearly all land at about 1:00. Also, 10 rds heats the barrel up....ALOT! In addition, the extractor seems to chinger up the rim a tiny bit, and not every single one.
These things are a hoot ! Don't know why I waited so long to add one to my safe .

All your findings are normal (mostly) for your type gun. What bullet weight in the PPU- 150GR? Did you get all your mags feeding correctly? If so, get the gun running smooth and break it in. Then you can start to tune the gas system. See my previous post. Stay safe and have fun.

 

[Gregg C]

All your findings are normal (mostly) for your type gun. What bullet weight in the PPU- 150GR? Did you get all your mags feeding correctly? If so, get the gun running smooth and break it in. Then you can start to tune the gas system. See my previous post. Stay safe and have fun.

Yessir, that's my plan...
The PPU ammo is 149 FMJ.
The other mag I have is from Magpul. I haven't done anything with it yet, but I'm certain I will. Someday when inspiration and motivation exist in the same room.... I'm sure it won't be hard, just painstaking and meticulous. I've got around 250 rounds thru it now. Amazing how long these AR platforms will run.

 

[C-130 Dude]

Yessir, that's my plan...
The PPU ammo is 149 FMJ.
The other mag I have is from Magpul. I haven't done anything with it yet, but I'm certain I will. Someday when inspiration and motivation exist in the same room.... I'm sure it won't be hard, just painstaking and meticulous. I've got around 250 rounds thru it now. Amazing how long these AR platforms will run.

I'm guessing the first mag you (fixed) was metal. Magpuls' will be problematic because there not metal. IMHO, my experience with AR's that demand metal mags is more trouble than there worth. I need a gun that will run with any common mag that I happen to be using. This is my requirement for home defense and shtf. Hunting and sport shooting is another story. Good luck.

 

[cohunt]

Almost any ar can be properly tuned -- you just have to balance carrier weight, buffer weight, spring tension, and gas flow.

I have an ultralight 308 that has a titanium carrier, 1 ounce ultralight 2 piece buffer, std carbine spring and adjustable gas block.

What I have found is with heavier components you need more gas but the system on a whole is more forgiving on multiple ammo/loads/suppressor etc--- with the ultra light components you really need to watch and adjust your gas settings for almost every difference in ammo etc ---- the lighter the components the less the gas and you don't beat up components as much as long as the gas is set right.

Glad we could help out with the mag lip tweak-- that is usually the first place to start.

 

[Gregg C]

Update: I've had the Tinker Toy out several more times now, and have had no feeding issues with that magazine. Thanks to all who chimed in here. Very much appreciated.
Tried the same fix, with a different approach, on the MP mag, and wrecked it. Grinding the lips away with a Dremel didn't work. So I ordered another mag from C Products Defence, this one a 10rd. Lots of issues with it. Lots of tweaking involved, but the knowledge gained here, shared by this community, enabled me to work it out.
Happy Independence Day !!

 

[wolffo]

Happy 4th of July !

 

[C-130 Dude]

Update: I've had the Tinker Toy out several more times now, and have had no feeding issues with that magazine. Thanks to all who chimed in here. Very much appreciated.
Tried the same fix, with a different approach, on the MP mag, and wrecked it. Grinding the lips away with a Dremel didn't work. So I ordered another mag from C Products Defence, this one a 10rd. Lots of issues with it. Lots of tweaking involved, but the knowledge gained here, shared by this community, enabled me to work it out.
Happy Independence Day !!

Great! Really glad you found and fixed the problem. It's a shame you had to use a certain type metal mag. Now you will have to get a handful for that gun to run. But it's worth it if that is what takes. I'll bet you learned a ton from your journey on AR tuning. Invaluable! Stay safe and have fun. Happy 4th of July, God bless America!

 

[Gregg C]

And for my money that makes it all the more enjoyable!!