Selecting the proper steel alloy

I recently began making some gunsmithing tools to sell and I was wondering how professionals choose which alloy to use?

I am sure that most jobs come with a specifical alloy that is to be use but if there is no spec what then?

I was using some 12L14 which worked very well but i read that it was not that durable. I next tried 1018 but when cutting threads this did not produce as nice a finish.

Is there a durable steel allow that is easy to machine and readily available.

I buy from Shapiro metals in st. Louis, MO but their prices seem high

LaSalle Steel made/makes Stressproof which is nice to machine and has useful wear and strength properties.

Cruicible Steel makes Maxel 3 1/2, which is even better.

John

I have no clue what stressproof or maxel is BUT we use a lot of 4140 around here. Machines very well, will finish real nice with a light cut and is readily available in an annealed condition. Very tough and can be hardened. The only one I have experience with is the 1018 which is .18 % carbon (did I get that right) while the 4140 is .4%. 1018 can be case hardened but it sounds like 4140 would do the trick. If you want to harden there are pletny of experts here that tell you the quick way to do it.

Stressproof is strain hardened 1144. Nice stuff to work with.

IIRC, maxel is a pre-hardened 4140.

ETD150, also from LaSalle Steel, is another 4140 variation which is pre heat treated and has certain additives for machinability. Its hardness and strength is in line with typical grade 8 bolts. For the strength level, the machinability is excellent.

One big problem with leaded screw stocks is their tendency to rust. Anything made from 12L material would have to be plated or otherwise protected if its going to be handled much because otherwise it will turn into a ball of rust in no time. Then you have a significant expense in case hardening for durability on top of the plating costs. Screw stock brings a premium price over carbon steels to begin with, and once you add the operations necessary for durability and surface protection, you're paying a very high price for ease of machinability.

If we knew a bit more about the specifics of what you're making, it would be easier to make a recommendation. Do you need more strength? Better wear resistance? etc etc.

1045 is nice to machine , and finishes well .
it will harden to a reasonable depth , and is
fairly durable .

4140 is very useful , and will harden deeper than
1045, but costs nearly twice as much.

on the other hand, 4140 prehardened to rc-35 or so
can be machined , eliminating grinding/hard machining
after h/treatment to fix the dimensional changes
from quenching.

what are the requirements? durability , finish ,
cost , heat treating , hard, tough , etc...

I am beginning to make some small gunsmithing tools, Receiver bolt face laps receiver turning mandrels.

I dont have any requirements as far as durability or wear resistance. After making and selling my first lapping tool out of 12L14 I became worried that the tool would not hold up.
Heres a pic of the receiver lap. I also want a easily available material to use. I dont want to plate or paint the stuff i make at least right now. Since i learned from this website that 12L14 rusts easily I'm going to quit using it. I may switch to 4140. Anyone know a cheap place to get it in St. Louis, MO


Thanks to everyone that replied

I hope this post is perceived as constructive but the threadform doesn't appear to be a true sharp-V...normally, the will tear right at the crest, but the 60deg profile is still clearly visible, it kind of looks like the "lead" was "split" while chasing and the threadform got hit with an unintended pass.

The knurl looks great!

No offense taken. All of my machining knowledge came from books and I am learning on my own.

The threads came out kind of rough and I went over them with a file which may explain the threads not looking like a V. The threads still screw into the receiver. Btw the threads are 55 deg for the mauser receiver.