doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Interesting Dr. Gaddy letter..

It's easy to demonstrate what you're describing at home. If you check a piece of steel with a magnetic when it's heating up, there will be a point when it suddenly becomes non magnetic. If you remove the heat, the piece will stay non magnetic while it noticeably cools and will slowly regain magnetism. It'll still be in decalescence much cooler than it took to put it there.

The interesting part of Doc Gaddy's comment was that he didn't catch the temp of the steel coming down, he brought it down to below 'critical', and then held it for an hour. The other interesting tidbit is he said that case hardened original receivers tested to have pearlite in the thin case layer, not martensite which would be the form it would be in if it were hardened steel.

I think file 'skating' and 'glass hard' is a bit subjective. When I ever do it, I'll only try it where there's no chance of showing. Just because the file doesn't 'bite' into the steel doesn't mean the finish won't get scratched up. I think case coloring is sort of playing games with poor heat treating practices in exchange for appearance and fit. I think that's Doc Gaddy's point. Only thoughts is all.

We should also remember that back when L.C. Smith, Parker and Ithaca (among others) started, 1020 mild steel with lower carbon content was the "state of the art" for forging receivers on drop board molds-- and "double fitting" was std. for gun making then- not until WRA, a pioneer in metallurgy working with USSteel, developed the M21 and the fitting of heat treated AISI 4140 nickel chrome moly alloyed medium carbon steels- as heat treated, eliminating a costly and somewhat in-accurate surface hardening technique- Dr. Gaddy was a very well informed man, and his detailed analysis and printed results are 'gospel"--

It's been too many years since Oscar shared here. He was spot on, in his letter to Mr. Brownell regarding temperatures. He often warned folks he'd help that the information was not correct from Brownell's. Drop a line to Mr. Schilling who's helping many European Manufacturers now if you're not convinced.

Geography for the Running Fox, and all.
Early morning 27 July this year, I drove down into Montezuma to "open up" Brownells. There they were....GONE.
An open "corner store" told me they had moved up onto I-80 closer to Des Moines.
So Brownells is now located in Grinnell Iowa - but NOT several klicks north up into the town proper (ask me how I know), but rather almost just right off I-80 exit.
Watch for the sign - which should BY NOW (one would hope) be raised and visible from the Interstate.
And the "new" Brownells, is NOT the dinky little order office where you ordered your parts on a "fill it in yourself on the pre-printed form" and then the staff went off into the warehouse and found your selected items for you. The new Grinnell location is a mega state of the art warehouse with a co-located large retail store. In the retail store, sit at the computer bank, follow the bouncing ball on the computer screen, submit your order, wander around for 10 or 15 minutes right in the big store, or sit down and read the interesting magazines in the commodious waiting room, and then your "picked order" from the co-located warehouse appears, pay the lady, and get back on I-80.