The term "sloppy" is relative... this is because "mil-spec" means there is a max and minimun tolerance for the machined parts. Take this example, ABC pin fits into XYZ hole, mil-spec on the pin is .250" +/- .003", mil-spec on the hole is .257" +/- .003"....Now if you have a pin machined at the max. tolerance of .253" and a hole machined to the minimum spec of .254" you wind up with .001" clearance... a tight fit. Now on the other hand, if you have a pin at the minimum, .247" and hole at the max, .260" you have .013" clearance, and a "sloppy" feel. So you could take your upper and go around to different lowers and custom fit them, or just buy an accu-wedge and tighten things up.

I have a DPMS 24" rifle, bought in 2005 and shot at least 2000 rounds per year, at least. Thats 14,000 rds... the rifle started out with a decent fit between the upper and lower, now it has a little more movement. Does it affect the accuracy? Nope, not at all.

Also, none of my DPMS fire control part broke either...