BCM uppers tighter than Colt uppers?

[30 cal slut]

I'm probably not saying anything new here, but I've noticed that BCM upper receivers are really tight going into the lower (a crappy old Essential Arms). There is absolutely zero play between the BCM upper and the lower.

I have a fairly new Colt Match Target M4 ... and the damn thing rattles. Even with an Accuwedge installed. Probably not a huge deal but I wonder how much this play is affecting my accuracy.

[spamsammich]

not at all.

[eagle5]

I've had the opposite experience, but then my situation isn't an apples to apples comparison with yours...

Both my LMT 16" and BCM midlength uppers fit nicely with my LMT lower. However, the same uppers have a little more play in the BCM lower. It's nothing that worries me, but the play was much more noticeable.

Correct me if I'm wrong, but it is my understanding that play between the upper and lower has negligible, if any, effect on accuracy since the barrel and sights are contained within the same unit, the upper.

[RD62]

My BCM Middy is noticeably looser on my Sabre and RRA lowers than my LMT upper. It's no problem, but you can tell.

-RD62

[comp1911]

http://en.wikipedia.org/wiki/Tolerances#Mechanical_component_tolerance

[Magsz]

My BCM upper is loose as snot on my LMT lower.

Its also not perfectly lined up at least on the outside with the receiver extension.

The gun shoots and does not appear to be battering the receiver extension so i really dont care.