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Making Double-Set Trigger Knock-Off From Scratch

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25 June 2003, 00:27
Nitroman
Making Double-Set Trigger Knock-Off From Scratch
I needed to make a new knock-off since the stock is too tall and the set trigger cannot reach it. I started out with all the good tools:
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And I am now in the process of roughing out the new piece:
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You can see I have some ways to go. My real concern at this point is getting the angles correct. My desire at this point is to recreate the exact same angles just the knock-off being a little deeper so the trigger arms can reach it.
I am open to any suggestions. I am using pre-hardened 4140 which I intend to case harden by placing in a charcoal powder filled black iron pipe and heating 'till red hot and keep it there for an hour or so then letting it cool. The I will heat the kicker until red and oil quench.
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[ 06-25-2003, 12:30: Message edited by: Roger Rothschild ]
25 June 2003, 00:34
D Humbarger
Nice German milling machines you have there Roger.
What steel is that you're using? Looks like stainless.
25 June 2003, 02:05
Nitroman
The steel is 4140, pre-hardened. You can tell it is different from any run-of-the-mill carbon steel when cutting it, the cut is very smooth and clean. I used a jig-saw to cut out the square and the files for the rest.
25 June 2003, 17:11
J Wisner
Roger.

You should have dropped me a line I still have a couple of dozen knock offs for the 93 Mauser.

Using 4140 you can have big problems with a water quench.

Carbon will migrate aprox .008" per hour at 1650 degrees F.

Soak the part like you said you were going to do. Then remove the part and heat back up to 1500 degrees or so and quench in oil. ATF or 10 to 20 wieght. Clean off well and draw at 675 degrees F for 1/2 hour, this should put the hardness about 48 - 50 RC.
25 June 2003, 17:21
Nitroman
Mr. Wisner,

Thank you for your suggestions. Before I do any heating I will re-read the webpage I downloaded that has several pages on temperatures and colors. I should call a welding supply house in Anchorage and get a selection of the crayons that melt at the specific temps.
25 June 2003, 18:01
<G.Malmborg>
Learn the color method, you will be amazed at how well you can do reading colors. Nice job with the files. Now you know why they refer to some files as "bastards".
[Big Grin]

Malm
25 June 2003, 18:51
smallfry
Roger... How thick is that piece? O-1 is easy to work with, and I use it oftan for internal parts.

Just make sure its not a dull red. [Big Grin]
26 June 2003, 09:26
Nitroman
Smallfry,

That is 0.250" thick, and wouldn't you know it...the knock-off is 0.240" thick. Such is life. This is why they make belt sanders. Oh, I never thought of O-1 or any of the other high-strength steels, I figured if 4140/4130 was good enough for a gun barrel it'd be plenty good enough for this. Besides, it was FFFFRRREEEEEEEE!!!

Malm, a question for you [Smile]

Know why I am using files when a Dremel and a carbide would be so much quicker?

(HEY! What are you doing HERE! You should be healing my rifle [Wink] )

[ 06-25-2003, 13:23: Message edited by: Roger Rothschild ]
26 June 2003, 03:48
<JBelk>
RR--

I wonder how the stock can be "too tall" and the magazine still fit. Wouldn't it be a lot easier to make the stock right which means the original trigger fits right?

The pack hardening chrome moly steel is an invitation to failure.

Cut it out of mild steel, polish, heat cherry red and dunk in Casenite, reheat to red and quench in water. Finished.

4140 is not good for gun parts unless you have really good heat-treat equipment. Mild steel and Casenite is a piece of cake.
28 June 2003, 06:13
Atkinson
I was wondering the same thing that Belk was, if the stock is correct then the triggers should work...