A friend just changed his American Spirit Arms A2 upper for a Flattop he bought in the EE. The lower is DPMS. He put the old upper internals and barrel on the new upper and went to the range with new 30 round GI mags with magpull followers and it would occassoinally feed. The rounds were stopping on the feed ramp and sometimes setting the bullet back into the case. He tried reloads, (which worked before) remington, WWB, PMC, and various surplus ammo, then tried the old mags and they worked better at first, then not at all. I have trouble believing that its the new upper, although all this happened after the change, but if I knew the problem you wouldn't be reading this. And for the latest twist, he took the rifle out last night and it worked fine if he put forward pressure on the back of the magazine.??????????? He says the magwell has quite a bit of play but we haven't compared it to mine so I don't know if its any worse then normal.

The old configuration shot great, both reliable and accurate, the new is neither.

Thanks
Mark

have him check how the barrel extension is mating to the new upper. if the upper has M4 cuts but the barrel extension is that of a rifle, that may cause the round to get wedged underneath the extension.

It does have M4 (type) cuts, but it is the same bolt/barrel combo, he only changed to a flattop upper, the old upper had the same cuts as the new. As far as fit, I can only same it looks the same as mine, we don't have any headspace guages. I would assume, and its only a assumption so if I'm wrong please let me know, but I would think if there was excessive headspace it would split cases?

Quoted: It does have M4 (type) cuts, but it is the same bolt/barrel combo, he only changed to a flattop upper, the old upper had the same cuts as the new.

The old upper was an A2, which does NOT have M4 cuts -- therefore, the old barrel doesn't have the M4 feedramps either. If the new upper has M4 feed ramps, then this may indeed be the problem. What brand of upper is it?

CMT Upper.