Aluminum barrel extension question

[gta_spec]

I see alot of guys online that have added an aluminum barrel extension to their M92 & M85 using the blind pin and weld method.
Some guys claim to use an aluminum pin and some guys claim to use a steel pin.

Obviously, the aluminum pin would provide a better connection at the extension weld joint, where as the steel pin would just get captured under the aluminum weld. The downside to the aluminum pin is that it could twisted off easier.

Is there a prefered method in the eyes of the atf? or am i missing something? Is JB Weld atf approved? haha

I woud also assume that the pin needs to extend into the barrel, not just the front sight block.

any thoughts?

[BPTactical]

I have searched and searched but I cannot find in writing the BATFE(HIJKLMNOPQRSTUVWXYZ) testing criteria for a "permanently affixed" muzzle device.
Rumour has it that the device must withstand 200 ft/lbs of torque.
With that being said, anything other than steel would have to have too large of a cross section to be practical.
A steel pin could be used provided it is sunk far enough below the surface of the aluminum so you could TIG an aluminum "cap" over the pin.
But then does that really meet the definition of "fusion weld"? I mean the pin is not fused with the barrel or device.
Iffy IMHO.
I always ask myself in iffy situations: do I want to be the BP Tactical vs the US case?