I like double rifles and i like to build stuff and have been playing with the idea of building my own, I have been researching some different materials to make the action out of. Has anyone tried using 4340 for a double rifle action? It is much stronger than 4140 at the same hardness and will bend further before braking. I guess I'm lookig for a very good reason not to use it, besides the fact it's a mother to machine.

Loren, I think you answered you own question. Why beat you head against the wall for a little unnecessary gain?

4140 is very adequate.

A few years ago there was a fellow on the forum who built a target rifle of 4340. I commented that it was a bit 'overkill' ,a fine steel for sure but not necessary. He built it anyway and won the major the tournament in his country !
But then if you were going to chamber the rifle in the 600 Overkill cartridge 4340 might be very appropriate !

Now that I think of it there was a member from Canada who made , from scratch a 2 or 4 bore double , took it to Africa and had fun !!!

I had planed on chambering it for the 12 gauge from hell. I followed the thread for a while and was quite impressed! I dont recall exactly what pressures they were running but i know it was getting up there. I know 4140 is a good steel but over built is under rated. Besides having never built one from scratch before I like the extra insurance.

If you are going to case harden it, you will want to use a lower carbon steel, like 8620.

Im not a big fan of color case hardening for the simple fact that it warps the action you just spent a bunch of time getting the barrels on face setting trigger pull and so on. I am not rulling it out and it really looks awesom! As far as using a low carbon steel i do know people who color case 4140 actions and it seems to work just fine.

Yes, they color 4140, but they don't add any "case" to it as it already has enough carbon. Different process and lower temps than used for low carbon steels. You can make 4140 brittle if you try to put a case on it so it has to be handled carefully. If you are getting warpage you are heating it too hot for too long. Turnbull knows how to do it correctly on any steel.

"Turnbull knows how to do it correctly on any steel"


Amen to that!

You might consider Rycut or equivilent. It has higher tensile strength and yield than 4350. It also machines easier. Heat treated to 29 to 36 Rc it can be machined at about 62% of AISI B1112. Gun barrels are made of this stuff.

Dave

George Hoenig, one of the best, if not the best, most talented old world gun maker in this country, used S7 for his rotary double rifles. S7 is a superlative outstanding alloy steel that is hard to beat for such use as he put it. Since you have to machine the steel a specific amount anyway, for a specific action, no matter what steel alloy you use, why use a cheap and inexpensive steel, when you can instead use a much better higher quality high tensile strength modern alloy such as S7, the best, when costs for the best are minimal, comparatively speaking? You won't find anything better than S7, and that is why George used it, trust me on this!

Oh Im sold on the coloring, I had no idea you could just color the action without casing it. Do you happen to know the number for Rycut, it makes it easier for me to find. As for S7 I suspose you can color that too right? I used to make punch and dies with S7 cuts like crap but it is super good material, Ill give it some thought.

Ryerson Steel, Rycut 40 ASM SA-230.

Dave

Perhaps you can "just color steel, without casing it," but I wouldn't fool with that sort of thing. The common coloring you see on firearms IS color case hardening; it both colors and case hardens the outer thickness of steel. Its main purpose is to give the case hardened surface, for wear friction resistance, etc., but a secondary purpose is to get the beautiful colors you see. I learned process from a very talented gun maker, a one time engraver for Colt, and also learned process in gunsmithing tech. college class in California.

And Turnbull has refined the process for higher carbon steels and can color without altering the heat treatment of them, so the average guy is smart not to "fool with it". I am not affiliated with him at all; but have used his services quite a bit for both low and medium carbon steels. Using the standard process of bone/charcoal heat treating will make a .4% carbon steel brittle. As for using a "better" steel; there is really no reason to; remember DRs were first made from case hardened wrought iron and plain low carbon steel from the late 1800s; modern chrome moly alloys are light years ahead of this. Why bother to re-invent something that is not a problem? Unless you just want to. Oh, S7 is a .5 percent carbon chrome moly manganese steel so you definitely need to be careful when heat treating that. You are getting into the "tool steel" range now. Is it necessary? And Rycut is just a trade name for leaded 4140; you guys are scaring me now. I don't know of any big barrel maker using leaded steel. Yes, it is easy to machine.