[sigmpx2017]

Anyone have experience with magazines from "A.S.C. New Britain CT?" I have a couple for my 9mm AR-15. They don't seem to feed reliably/at all depending on ammo.

 

[Willard]

No experience with those, only the 5.56/.223 version and no problem.

I'm going to ask your "brand" of AR, if it's not a Colt, it could be a little more understandable. Since there are so many different versions of magazine adapters, the specifications they worked off of, to build their magazines, may cause reliability issues, due to tolerance stacking. And besides, I have no idea if they used a Colt as their pattern!

I would contact the manufacturer of your lower / magazine adapter, and see which brands they recommend, and go from there!

 

[sigmpx2017]

No experience with those, only the 5.56/.223 version and no problem.

I'm going to ask your "brand" of AR, if it's not a Colt, it could be a little more understandable. Since there are so many different versions of magazine adapters, the specifications they worked off of, to build their magazines, may cause reliability issues, due to tolerance stacking. And besides, I have no idea if they used a Colt as their pattern!

I would contact the manufacturer of your lower / magazine adapter, and see which brands they recommend, and go from there!

It's a LAR multi-caliber lower and CMMG 9mm upper. I don't remember who made the mag well adapter.

 

[Willard]

My best advice would be to get 1 each of several brands. I know some used modified Uzi magazines, as I believe Colt originally did. If there is any adjustability in your magazine adapter, it sounds like a day at the range is in order. I would initially suggest using round nose Full metal jacket, to cut down on variables. Things such as the height of the magazine in relation to the feed ramp. The feed ramps angle toward the chamber. So many variables involved, it could take you some time to sort it out.

Good Luck, as an alternative, I would suggest getting a CMMG mag adapter, as it should be more compatible with your CMMG upper, and get a couple CMMG Magazines. Once you get it ironed out, you could possibly modify your other magazines to duplicate the ones that work reliably!

 

[Twister]

I have a bunch of ASC's I use in a Colt 9mm with no problems and some 223 ones that work good as well.

Like Willard I would suggest trying a CMMG mag adapter, maybe theirs is slightly different to match their upper. Colt and Rock River Arms are based on Uzi mags and I personally have modified and used them in both so that's a good suggestion as well.
Good luck and let us know how you make out.