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Had a vintage .22 firing pin snap clean in half on me yesterday
It was an old Marlin 60 I was cleaning for a customer. The pin just sheared right at the neck when I was checking the action. I had to make a new one from scratch using some O1 tool steel I keep on hand for small parts. Took about two hours with the lathe and files to get the angles and hardness just right. Has anyone else had luck with a specific type of steel for these older rimfire pins? I'm wondering if 4140 might be better for the shock.
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ray_king5mo ago
Ever try heat treating the O1 after you shape it? I've found that helps a lot with the shock resistance on those old pins. What tempering temp do you usually run?
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wesleyburns4mo ago
Funny you mention that, I actually heat treated myself out of my own shop one time. Left a batch of O1 pins in the toaster oven a little too long and had to air out the whole place for the rest of the afternoon. For these little rimfire pins I do a quick torch heat to non-magnetic, let it air cool, and then temper at 400 for about an hour. The 400 gives it just enough toughness without making it too brittle. 4140 would probably work too but I've never tried it on something this small, plus machining it without carbide is a pain.
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