I'd like to see what the Spike's pistol buffer tube looks like: is the end cap rounded at all? I'm thinking about replacing mine with a more shoulder-friendly tube.

It is perfectly flat at the end.  This build is missing a bunch of stuff still, but you get the idea.

I have a nice rounded cane/chair tip on the end of mine. The tip is tucked under the foam for a nice finished look. I know what you mean by shoulder friendly. Sometimes it will slip from my cheek weld and knock my shoulder pretty good.



I assume this is why your looking to do yours also, because as everybody knows, if your adding anything or changing the tube to make it easy to shoulder then according to the NFA you are "redesigning or remaking" it to be fired from the shoulder. And that would be considered making a rifle. If it has a barrel under 16" that would be a illegal SBR.



Just so you know, so next time you can "clarify" your legal intentions before posting where anyone can read them.

The term ``rifle'' means a weapon designed or redesigned, made or 
remade, and intended to be fired from the shoulder....