AR500 Steel. Some lessons learned.
As some of you know rifle steel is the bane of my existence. I hate that shits.
Because I very frequently have to repair it after an assortment of morons shoot the hell out of it with steel core or "penetrator" ammo.
In that I have learned a few things through experience I would like to share with you.
1) Forget about "just" heating it. You know, like what would happen if you welded on it or cut it with a torch. You WILL destroy the temper, rendering the steel far too soft for even repeated centerfire handgun hits. The pistol bullets probably won't go through it, but it will crater it badly. In case you don't know; that is a really bad thing. It can and does create ricochets - sometimes whole bullets, sometimes just fragments, at angles you simply can not predict.
2) Because I am an old guy, I long ago learned about oil tempering steel. It is a method that induces SURFACE hardening via quenching the hot steel in oil. This works exceptionally well in applications NOT subject to harmonic vibration. You know, like what happens when you shoot a steel plate with a gun. If you shoot it, it WILL crack the steel. Maybe not on the first hit. But by the 150th one, bet on it cracking. See "ricochets" above for why that is really bad.
3) I hear you thinking. You are thinking; waitadamnedminute! I have seen AR500 that has been cut into a myriad of shapes and sizes. They didn't do that with a flippin hacksaw! And you are right. Here is how that works. And it will also help explain why AR500 targets seem obscenely expensive . . .
The target manufacturers order NON TEMPERED steel that AR500 is produced from. It is an alloy. They cut and fabricate whatever shapes and/or sizes they want, usually with a cutting table whether it is laser, plasma, or conventional oxy/acetylene, weld it all together conventionally (low hydrogen rods or wire) and then they send the shapes out to be tempered tot he appropriate specifications.
So . . . the problem remains; howinthehell do you repair AR500 steel shot to death by idiots?
I've been researching this topic for a very long time now. Testing and debunking or validating. Up until very recently it has been 100% debunking. Then I ran across a thread on a machinist forum. Had NOTHING to do with shooting, these guys seem to mostly be working in the mining industry doing tooling for mining machines.
What I learned I found just too far fetched to be believable, so i had to test it.
Salt. Plain old table salt. Iodide optional.
Mixed TWO full 26oz paper "cans" per gallon of fresh water. Stir until completely dissolved. Then use that as a quench.
By Jove - it works !!!!!!
I resurfaced an 8" plate to get it nice and flat and pock mark free. Welded and ground - with an angle grinder - the hell out of it. I then welded a 1/2" (the size that requires a 3/4" wrench for those less fastener size fluent) grade 8 bolt to the back of it and retempered it using the salt quench. At the time the only clean flat container I had was shallow, so the threaded part of the bolt stuck up in the air, while the entire plate and weld area where I attached the bolt was submerged.
I hung it back on a piece of conveyor belt out on the range at 200 yards. I had JUST walked past the shooting line and called the range hot when it took its first 30-06 hit. Then about 19 more of them. Then countless poodle shooter and .308 hits in the next two days. On the morning of the third day I noticed the plate was down.
I cussed most every inch of the 200 yards out there to it.
The surface of the plate was paint free, but there was not a single dimple in it. The grade 8 bolt broke right exactly where it had stuck up out of the quench.
FWIW. And now you will know why I left the range to go get salt. :P
