Nope, the smaller mil spec tube is stronger than the commercial. Has to do with how it's made.
Commercial is cheaply made and the threads aren't full point, they snap off right behind the castle nut. And yes I have seen em break not just something I'm guessing about here.
That's a blanket statement that is not accurate in all cases. I can provide you with commercial diameter extensions that are absolutely identical to the mil spec extension in every way but diameter. Additionally, the vast majority of the extensions that are commercially available as "milspec" extensions are not actually made to meet the specs.
I am sitting a few yards from a several thousand true "milspec" extensions that are headed to the military as I type this, btw.
