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Posted: 12/11/2005 11:37:02 AM EDT
Some folks were asking me how I modified my 9mm AR-15 Promags so that they became more reliable. After studying why my Colt mags worked perfectly and my Promags gave me lots of feed related issues, I decided to modify my Promags. Keep in mind, the Promags are cheap and cost 1/6th of what the Colt mags run, so I was able to afford to experiment a little bit.

Here is a photo of an unmodified Promag. Notice how the feed lips are thick and are absolutely square (causing the cartridge to sit lower in the magazine).





Using a dremmel, I rounded the edge of both the feed lips so that the cartridge would sit higher and feed properly. Before the modification 2 out of 3 cartridges would nose dive and jam. After the modification, my round nosed bullets feed 100%. Here is a photo of the modified feed lips.



Also note that the follower will ride a little higher and push up on the bolt catch a bit harder providing a malfunction free bolt hold open after the last round is gone.
Link Posted: 12/11/2005 12:24:28 PM EDT
great info thats for taking the time to post
Link Posted: 12/11/2005 5:02:17 PM EDT
Cool. I've got 5 Promags that don't work in my gun, but not for that reason. They don't lock in! Just a little "pull" on them and the come right out. The 6th one works fine, but is appears to have a small "lip" on top of the mag catch slot. So if I ever get them working (probably just have to return/exchange them) then I check into the modification for reliable functioning.

Now if my Colt mags would just operate the BHO like they are supposed to, I'd be a happy camper (Hahn bottom load block.) Those crappy plastic followers that come with the Colt mags are no match for the older alloy ones....
Link Posted: 12/11/2005 6:53:05 PM EDT
You guys should send that info to Promag since they never bothered to engineer and test thier own product.

Never trust a magazine made in China.
Link Posted: 12/11/2005 6:58:52 PM EDT
I've got to say it, the magazines really are crap. After the modifications, I still would only use them at the range. There is no substitute for Colt 9mm mags!
Link Posted: 12/14/2005 10:01:27 AM EDT
I'm not doubting you at all Tomster, I've had boo-koo problem with other Pro-Mags in the past.

I recently got several from Midway for my RRA 9mm, and all of them work fine. Holds the bolt back after the last round, flawless feeding. In my carbine, they work as well as the one Colt mag I have, and I bought 7 of the Pro-Mags for what I paid for 1 Colt maghem
Steve
Link Posted: 12/14/2005 12:47:22 PM EDT

Originally Posted By Scollins:
Cool. I've got 5 Promags that don't work in my gun, but not for that reason. They don't lock in! Just a little "pull" on them and the come right out. The 6th one works fine, but is appears to have a small "lip" on top of the mag catch slot. So if I ever get them working (probably just have to return/exchange them) then I check into the modification for reliable functioning.

Now if my Colt mags would just operate the BHO like they are supposed to, I'd be a happy camper (Hahn bottom load block.) Those crappy plastic followers that come with the Colt mags are no match for the older alloy ones....



Did you try to screw in the mag catch yet?
That helped me some what.
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