12L14 is great from the gunmaker's perspective. 1137 works very nicely also.
Are they appropriate for gun barrels? I have no idea. What I do know is, I have NEVER personally seen nor heard of one failing when used with blackpowder.
It's unfortunate that in today's litigious society, we have to be concerned with what the morons might do....
To go back to the original question: as far as I know, Getz, Rice and Colerain use 12L14 primarily. GM is 1137. I have had barrels from Bobby Hoyt that were either 12L or 1137, at least they worked like it. Ed Rayl's barrels were always kryptonite and ready to withstand a nuclear blast. Orion seemed to be 12L.
ALL of the barrels mentioned are quality barrels and will serve perfectly fine with black powder loads.