Is this barrel 16" with flash hider pinned & welded? — 1 Answer

Yes. That's the purpose of why they pin and weld the muzzle device so that it is not easily removed for the purpose of meeting the 16" legal length requirement. That's the only reason you would want to pin and weld a barrel to avoid dealing with tax stamps or being limited to building an AR pistol with a brace, because otherwise it just creates additional hassle, in my opinion, if you would like to change muzzle devices or to pull off a gas block to address an issue; now you essentially have to pay a gunsmith to get involved in the process which is not always cheap, other wise be able to easily perform for free in just minutes by yourself at home. Still, the 14.5" pin and welded is worth it imo because it's a more overall versatile length and still meets the requirements and your really not losing much velocity from a 16" barrel.