[rhmc24]

A bit of case history with a Colt 1905 .45ACP. When the 1905 was in production, prior to the 1911, the .45ACP cartridge it was designed for and the US Military .45ACP had a similar relationship to the .38ACP and .38Super, though not as wide a gap in relative power.

The 1905 & 1902 are exactly the same gun, but for parts related to cartridge size most parts interchange. A 1905 slide with fit the rails of a 1902 & vise-versa. Failures as discussed here are not uncommon in the 1905. I have seen three and owned one. By failure I mean cracking at the front of the slide, both sides at the front of the slot for the slide lock. The crack proceeds upward & forward at maybe 45 degree angle.

The cracks on the one I had were open close to 1/16". Apparently that affected the relationship between the notches that lock the barrel into the slide just forward of the eject port because a previous owner had installed shims just ahead of where the rear barrel link meets the frame. From that I think when the cracking reached some max amount, malfunction occurred -- which probably would tend to eliminate catastrophic failure. The slide material doesn't seem to be heat treated, just a strong, tough and fairly ductile steel.

In my case, I 'V-ed' the cracks, welded them up and filled the gap at the slide lock with weld & squared off the muzzle of the frame. After refinish prep of the slide and rest of the gun I sent it to Turnbulls & had the markings replaced & charcoal blued. Since I knew where the work had been done, I could see it but nobody else has.

I think it was this one:

 

[rhmc24]

For whatever it's worth after bluing after a weld ---- back in the day when I was busily working on clients mostly pre-1800 guns, I now and then got a job to restore a barrel to its original length. That produced a joint of three different steels, the original, the added piece and the deposited weld. With that I had a joint that showed - whatever I did in finish. Old guns usually wanted a brown or an antiquish bare iron.

Then I was using a stick welder with electrodes least in alloys I could get. Later I used a MIG welder with the standard wire.

I can't recall how I discovered it other than trying thru frustration, but the fix for me is to do my almost finish polish, then heat the welded area and immediate area red hot, then after cool do finish polish.

I had done a weld on a Colt auto and talked with Turnbulls who predicted the weld would show after their blue. Minor weld, I gave my treatment, figured I could touch up somehow, I sent it anyway and it came back hardly visible. Another of my 1902 re-creations had been victim of at least half dozen bubba events of saw, file and grind, which I welded up, gave my red heat treatment. One I missed and it was plainly visible that I just left as-is, something a future owner might guess about.

I've used Turnbull charcoal blue which may or not give a different result from other hot dip blues.

 

[rhmc24]

Mine is a MIG, not a TIG, a Lincoln maybe 10 years old now, 100 Amp, their smallest at the time. I bought with it the gas bottle for inert gas it needs. Same kind of welders can use a wire with flux in it that eliminates need for the gas. I don't know what if any difference in performance. There must be some reason for the two kinds.

I once had a TIG welder, roughly same idea as the MIG but the MIG deposits the wire into the weld while the TIG just draws an arc from an electrode that doesn't melt and you use a separate rod filler. It requires inert gas to operate. One of its benefits is it will weld aluminum if you feed it with aluminum rod. Versatile, but I got rid of it because in NY where I was at the time, you couldn't own a gas bottle and the gas supplier kept harassing me because I was keeping his bottle tied up with the little amount of welding I was doing.

The idea of using some of the donor material as filler could probably work with a TIG but not with the MIG system due to its wire being the filler.