Yep, its a Rifle Shoppe lock then.
I can usually get 6150 springs sufficiently hard quenching in WD40. On occasion, though, it doesn't get hard enough, and I have to warm the oil first on a coffee warmer plate (I think 104 degrees is supposed to be the ideal temperature) and then it will harden enough. I HAVE to warm the oil with O1 Siler tumblers and sears...and even then, I don't think it's hard enough. I really don't like O1 steel...
but, I live with it...
Temper them tumblers and sears down to brown with the propane torch. Heck, you could probably go to purple or blue with this stuff, as 4140 is an incredibly tough and hard wearing steel, and doesn't necessarily need to be rock hard (which is why so many modern guns use this steel).
Springs I temper down "all the way" to a nice dark gray blue with a propane torch (the colors go: straw, brown, purple, blue, light blue, red [which you may or may not see], and then dark blue gray, which is as far as you can go before having the steel begin to glow in dim light again). Heat the part slowly and lightly, and move the torch all over the spring back and forth until it is dark gray-blue all over. I hold it at heat here for several minutes with the flame of the torch lightly feathering the part. Set it aside on a piece of wood or a brick or something non metallic, and let it cool. It's simple and easy. There are about a thousand equally valid ways of hardening and tempering springs. :winking: