Getting it red hot in a hurry is the idea so you don't damage the bluing on the frame.
Yes it bends easily when red,,steel does that,, and that's also the idea. No chance of the recv'r slipping in the vise by putting a lot of un-necessary pressure on the shank trying to bend it cold. A #2 tip works well. Works good for welding in markings /lettering.
"...we are talking about cylindrical threaded components here..."
Why yes we are imagine that,, and to think we heated to red about 1/2" or less of the length of that piece of threaded (on each end) round stock that's slightly bigger in dia than a common pencil ,, and then bent it a couple degrees.
Wow, Panic Alert,, call Engineering Dept before proceeding.
You can make a big project out of it,,or not.
No damage to to gun, or componet parts during the fix or later. I saw many of those guns later as they returned for strip downs & cleanings.
You can just as well give the shank a wack or two with a heavy hammer over a solid support to bend it cold while in place. Most probably what the factory did, but there's the chance the end threaded into the frame will bend and/or loosen on you doing it like that. Not having replacements at hand makes the hot bend a better choice for the parts starved.
It's not a big deal. I've probably done 30 to 40 of them in the last 40+ yrs between 12's and 97's. Even a couple 42's.
I learned it from other gunsmith(s) who learned it somewhere else,,,
If you can't heat that stock shank up to red w/o melting it in half, don't play w/the torch.
No I don't have any certification in anything that I can think of.
The best way to preserve the "bluing on the frame" as you said- assuming that you really mean the receiver here, the proper term for the Model 12 repeater (and the Model 21 double gun as well) is to first remove the shank, as I always have done--yes, be careful with whatever heat source you use, whether an oxygen fueled torch (make mine a Victor please) or propane units sold at Hardware stores all over America- Turner is my preference here-
Best way, IMO anyway-- is to pack the shank with the "slave pin threaded bolt" inserted into heated charcoal, wrapped in heavy asbestos sacking, that way you get even heat input into a cylindrical (sorry if that is too technical a term here) so let's say "pipe" as that is what the shank is, albeit a tapered OD shape--instead of the spot heat application from a torch tip, even moving as is the proper technique.
As to the often abused term: "certified" I knew a few dudes who said they were "Certified" welders- BS- they worked in a production Fabrication factory welding with MIG (Metallic Inert Gas) aka- 'wire welding" in the 1G position with the metal sections to be thus welded together clamped in a jig or fixture-
Any Willie off the pickle boat that can law down a bead of caulk from a caulking gun in the down-hand position can become a "certified 1G position MIG welder)- assuming someone with the right welding op. background sets the wire feed speed (amperage or "heat" for him) as well as the OCV- open circuit voltage- affects the shape of the weld bead as deposited in the joint- along with the wire AWS rating, diameter, coating and shielding gas delivery pressure, flow and admixture- if not a straight 100% as delivered shielding gas--
