Noticed something interesting about the new Aero Precision 7075 buffer tube kit I got a few weeks ago. There's no "lip" between the threads and the stock mounting ridge:



Here's the older tube listed on Aero's site, with the same SKU (APRH-100151):



I first noticed Anderson using this tube style. What's interesting is that someone in another thread noticed that their Anderson tube had a slight extrusion mark in the same place as my Aero tube.



I wonder if Aero and Anderson get their raw extrusions from the same place, or if they both just use the same die if they make them in house.

i just wonder if the M4 carbine mil-spec calls for the step (or "lip"), or not, on the buffer tube.

I don’t know if there’s a strength thing to it, or if that’s just how Colt was able to design the part originally.

Most buffer tube failures I’ve seen online were commercial tubes or 6061 mil spec tubes, but they failed at the threads.

All I’ve noticed is that some of my buffer tubes (all mil-spec) have some rough and pronounced step or lip to them. Others are damn near smooth / same diameter throughout.