I've not worked on a 102 yet.
But I have threaded/chambered/fitted various barrels to AR barrel extensions. Breeching is very straightforward, easier than say, a Remington 700. The barrel must be turned to desired contour, including the correctly sized gas block seating area, the gas port located and drilled, and muzzle threaded. Very doable.
It is good news that the barrel extension is not a unique proprietary part.
Incidentally, take-off sporter barrels can be repurposed. For example, a Savage .223 barrel can be fitted to an AR barrel extension without the use of a reamer, if the machining is done very carefully. I missed by a few thou, had to finalize headspace with a hand turned reamer. Diameter at the gas port was undersize. Bored an aluminum sleeve, drove it into position, and turned it to gas block diameter with a shoulder to seat the gas block. 1-9 twist, shoots 69gr SMKs very well, and the light sporter contour makes for a good handling rifle.
