I have a DPMS 16 inch carbine that I am quite fond of. I've had it for a couple of years, and it has been accurate and reliable and until now I have had no problems. The only regular capacity magazines available locally were orlite and British SA80 steel mags. I've used these extrensively and have had no problems, other that the feed lips of the orlites being a bit on the fragile side. With the end of the ban I went to Guns and Ammo today and picked up several Colt 20 rd magazines, marked LEO only. I like the 20s for aesthetic reasons. Here I was all excited about my purchase only to get home and discover that none of the mags fit in my well. It was like they were just slightly too large. They would slide in place and lock if I used considerable preasure, and were difficult to pull from the well. There are visible rub marks at the front of the mag body (2 straight lines about 1 mm in from the edges of the mag). If it were only one or two mags I would be willing to think it was a mag issue, but it is all of them. If it is my magwell and it is out of spec, how big a repair issue is it? It can't be a big variance, because the orlites and Brit mags all work fine. Any suggestions?

No to all the above.  Its just like the darn things are too big or the well is too small.  They go in about an 1/8 inch just fine and then stick.  I got a buddy bringing a couple of USGI mags by different makers by so I can see if maybe the Colt 20 rd mags I have are just a touch out of spec.  Failing that, I guess I'll just leep using the Brit mags .

Believe it or not I just got outta the gunsmith with a problem with my Bushy bolt not locking back, he takes a micrometer to measure the magwell and says it the Colt mag that has the problem, never mind that the Colt mag works in all the rest of my AR's including another Bushy. The micrometer measures my Bushy magwell a little longer than my Colt's (BTW I had my Colt M4 upper in ther for a headspace check) he tries a GI mag with a green follower, believe it or not, it locks back.....when he stuck the Colt mag back in and wiggled it back and forth, the bolt catch sliiped under the follower of the Colt mag....

Someone is not going to like this but I have had several post ban guns with extremely tight mag wells . NONE of the PRE'S I have or know of  ; Have had this problem.   I have had a post -ban or two that would drop mags correctly but I have yet to experience a tight mag well on a pre-ban lower ..............J.C.

Does your trigger guard stick into the mag well? Does any portion of the upper hang over the wall of the mag well? Do the mags fit and function with the bolt locked to the rear? Do the mags fit and function with the upper removed

What can be done if a portion of the upper does hang over the wall of the mag well,  Is itr dremel time or time to buy a new upper?