I finally broke down and purchased a DPMS AR15, but I seem to have a problem with it - feeding from Thermold magazines will make it function like a really really bad single bolt action, making me use Forward Assist, and the charging handle every cycle - which in turn causes occasional doublefeeds.

My question is:  Is it the magazines, or is it the gun?  The gun is brand new, never been fired, everything is showroom stiff.  Someone suggested for me to loosen the magazines up a little by fully loading them, and leaving them loaded for a day or two.

Can't comment directly on DPMS products, but you shouldn't be having the problem with the Thermolds. Couple of questions.

Are the mags new too? Occasionally brand new Thermolds are a lttle thick right at the top of the feed lips, and will rub slightly against the bottom of the bolt carrier. Working the bolt assy back and forth a few times should cure this.

Have you fired the gun and had the feeding problem, or have you just manually cycled ammo thru it? If you haven't actually fired it yet, take it to the range and see if the problem doesn't sort itself out. If you have shot it and had the problem, look for rub marks on the very top edge of the mag feed lips.  That's about the only place on the mag where the bolt assy could hang up.

Every Thermold I've ever used in my Bushmaster needed the bolt run across it 20 or so times, then it worked fine.

On my Bushmaster, the top right feed lip had the slightest amout shaved off by this action, then worked fine with no more wear on the mag sonce.

But it did mis feed (bolt grabbing the round halfway up the case and sliding it out of the mag) until worn in.

Along the same line; A buddy bought some new Thermolds for his new Armalite and they won't seat/latch. Any cure?

My personal experience with Thermolds in my Bushy.  H21 work without mod, H22 needed some slight dremeling above the insertion rim.

Thanks for the info. I will relay it on to my friend.

Well, I took some advice - and shot some more rounds through the rifle - which seemed to loosen the piece up a little, but feed problems remain, but a little less frequent now.  I figure this is a process of trial and error - just keep trying variations until it starts to work really good.

The accuracy is quite nice, now I just need to get a comfortable shooting position, and sighting procedure down.