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View Full Version : 4140 steel vs. 4340 for a handgun.


tonerguy
November 23, 2001, 08:16 PM
Any metallurgists out there? I understand that 4140 is the steel alloy used to make most forged frames and slides for 1911's.

I'm told that 4340 is being used in some new 1911's - Valtro's. It is supposedly a little better for wear , but harder to machine.

Any informed opinions?

WESHOOT2
November 23, 2001, 08:46 PM
What does Caspian use for their carbon frame?

I'll bet that's an informed opinion.

kurt IA.
November 23, 2001, 10:04 PM
4140 In its annealed state has a tensil strenght of 95000 lb/in.2. Normalized it's 148000. 4340, is 108000 annealed, and 185000 normalized. Both are used for the same things, shafting, gears, exc. Hardness has the 4340 just a little above the 4140, 61BHN in the normalized state. The 4340 also has a higher core hardness than 4140. The Yield strenghts are 4140 annealed, 60500, normalized, 95000. 4340 is 68500 annealed, and 125000 normalized.

tonerguy
November 23, 2001, 10:51 PM
How might these numbers relate to a handgun? Longer life? Overkill? Any downside?

Thanks.

kurt IA.
November 24, 2001, 10:33 AM
I don't think you would be able to see any derfrence. Wile the higher hardness would lead to less long term wear, it would also add to britleness. Most firearms are 4140, harden to around 30 RC. What one wants is a fair hardness and a soft center, to ade in stayable and prevent failing, do to brittlenes.

Watchman
November 24, 2001, 08:17 PM
4140 appears to be a lot easier to aquire thtan 4340, at least in my area.

4140 is easier to heat treat than 4340 , which just about requires a computer controlled oven to get it right.

4140 on the other hand, can be heated to cherry read and quenched in heated oil and then drawn down to required hardeness.

This is why gunsmiths have been using it for decades as it require little in the way of tools. A torch, a heated coffee can full of oil at 150 -200 degrees and some tongs to hold your parts are really all that is needed.

4340 has a tendency to get very brittle if not done exactly right. As you can see by the tensile strenth posted in the other article, you really arent giving up that much in the way of strenth.

I made a bolt and the receiver for my .50 BMG out of 4140. According to the book, the hardness was required to be from 44-46 Rb. As it turned out, it was a perfect 45. I had a freind of mine that builds knives for a living heat treat in his electric computer controlled furnace, just to make sure we got it right. For all the other parts that reqiured certain hardnesses, I did them with a torch and heated oil. I've shot close to 1000 rounds thru that gun and nothing has broke yet. In fact, it dosent even look like any wear has taken place on than the bluing on the bolt.