How Much Heat is Too Much?

[nhcruffler]

Hello THR. I am getting ready to modify a mauser ( 98) bolt handle. I know you are suppose to use a heat sink & heat control paste because too much heat can soften the "third" lug that is near the handle. My question is just how hot do you have to get that lug to soften it? Are we talking cherry red or just a couple hundred degrees? I must have read volumes on forging & welding bolt handles but never saw an answer to this. Thanks, nh

 

[rcmodel]

It's not the third lug you need to worry about so much.

Too much heat without a heat sink inside the bolt, or a forging block to protect it will result in scale & slag building up on the bolt shroud threads inside the bolt, as well as annealing the cocking cam next to the bolt handle shank.

Then you will have a rough cocking rifle, and there is nothing you can do about it short of replacing the bolt.

As for how much heat is too much?
If the steel turns blue it was too much.

rc

 

[BBBBill]

Great advice from rcmodel. I don't do the welding myself, but I always do the setup for the welder and I'm always overcautious. I pack the interior of the stripped bolt with plumbers heat control paste, thread in a heat sink, and then cover the exterior of the rear of the bolt with heat control paste leaving only enough of the bolt handle stub exposed to allow welding. The rest of the bolt never gets hot enough to be uncomfortable to hold.

 

[nhcruffler]

Thanks rc & bb. That makes sense when you think about how much ( or little ) heat is required to spot anneal something ( like a receiver ).

 

[Jim K]

Heat control paste doesn't really control the heat; what it does is keep air away from the hot surface so the oxygen doesn't cause the steel to burn or change color and the bluing isn't damaged. It is not intended to be used instead of a heat sink, but as a supplement to it.

I always used those iron blocks for bending a bolt handle and that in itself, when clamped in a heavy vise, is a good heat sink. I also used an old ground rod shaped to fit the interior of the bolt (copper is a good conductor), plus wet cloths on the front of the blocks at the bolt lugs. I never used a heat paste and never had any problems. Of course I had to polish down the bolt after bending and/or reshaping.

FWIW, I don't like to weld on a bolt handle; I can turn down one and stretch it, reshape the knob or about anything else that can be done without taking a chance of a weld-on handle coming off. (I know yours would never come off, but I have seen a lot that did, which is why I always forged them down unless the customer demanded a weld-on job.

What I did use heat paste for was things like silver soldering sights and soldering shotgun choke devices, where I needed to keep the bluing from damage. I also used it on the inside of the barrel, again to keep oxygen in the air from damaging the bore.

Jim

 

[Runningman]

Are we talking cherry red or just a couple hundred degrees?

It somewhat of depends on the alloy of the steel. But generally on steel lighter blue is around 500 degrees F darker blue is around 550+ degrees F. You DON"T WANT TO SEE LIGHT BLUE. So part should be kept below 500 degrees F. Allow a buffer zone and limit area below 450 Degrees F.

 

[dirtyjim]

i prefer a welded handle to a forged but use whatever works for you best.

i also don't worry about the cocking cam, if i think it got to hot i just heat the cocking cam end of the bolt to a dull cherry red and quench in oil.

 

[fguffey]

Like Dirtyjim said, I prefer the longer bolt handle and when heating the rear of the bolt for cocking use a 5 gallon bucket full of water, hold the bolt under water and only expose the part you want to heat and harden, when it gets to the correct temperature, pull the bolt under water.

F. Guffey

 

[nhcruffler]

I got sidetracked and forgot to check back for more replies. Even more good advice. dirtyjim, I didn't know you hung out on this side of town Thanks All, NH

 

[dirtyjim]

dirtyjim, I didn't know you hung out on this side of town Thanks All, NH

nh, the entertainment value is the main reason i hangout here.
the gunsmithing section is pretty decent but its hard to keep a straight face in many of the other areas of this forum