Drill/tap M98 Receiver: Case hardening is too hard(?)

[TomBulls]

Hey, guys- help me out, please.

A gunsmith is working on one of my rifles right now, and I need him to drill/tap a 1939 M98 Mauser receiver.

He's telling me that he doesn't have the right equipment to drill/tap this receiver because the case hardening is too hard.

It started out with the high-carbon drill bits being dulled before making any serious purchase on the receiver, and then he tells me that he needs to use some high dollar porcelain drill bit which requires it's own special holder. Now we've broken two of the porcelain drill bits and the days and weeks are piling on with no end in sight. That I am only being billed for labor and not for these other consumables, which are rapidly increasing his costs, is convenient-- but what I really want is to get my rifle finished.

My dilemma is that I don't know anyone in the area that I trust to do this sort of work. The last guy I had to do similar work on my rifle, well, that was the last time I'll ever let that guy touch any of my rifles again... So, I'm sort of stuck. The guy I'm waiting on right now is school trained and does all of his work at a store-front. He's a new gunsmith, so I'm guessing that he's still learning a lot about the trade, right?

Here's my question: Is he truly just dealing with an exceptionally tough case-hardened receiver courtesy of pre-war production standards, or is he lost-in-the-sauce and B.S.'ing me? Is there something that he SHOULD be doing to more successfully accomplish this job?

-thomas

[Bren R.]

Someone should be along soon to suggest spot annealing.

Bren R.

[TCLouis]

OR maybe carbide bits

[FrankG]

If you make a deep enough center punch mark with a small center punch you will have no problem ! Ive done bunches and bunches with no need of annealing. Only annealing Ive ever needed is on Springfield and Enfields.

[Alan in Vermont]

If it is only case hardened it should be possible to grind through the case with a small round stone in a Dremel tool. If it is heat treated all the way through that is a horse of a much different color. I'm not sure if spot annealing is a viable option for through hardened receivers or not but it surely has a place on case hardened ones. Or maybe it's the other way around, my memory fails me on this as I have never done it, only read the procedure. I didn't ever stay at a Holiday Inn Express.

[largom]

A small carbide ball nosed end mill or a carbide center drill will cut thru the hardness and then you can use the required drill bit. Is your smith using a milling machine or a drill press to drill with? Speed of the drill bit can be very important. I have drilled and tapped dozens of 98 Mausers without any problems.

Larry

[TomBulls]

A small carbide ball nosed end mill or a carbide center drill will cut thru the hardness and then you can use the required drill bit. Is your smith using a milling machine or a drill press to drill with? Speed of the drill bit can be very important. I have drilled and tapped dozens of 98 Mausers without any problems.

Larry

I don't know which he uses, to be precise, but it is a bench-mounted vertical drill with a rotary handle for raising/lowering the bit.

Thanks for the tips. I'll recommend that he read-up on spot-annealing, or perhaps look into the use of these other bits before trying to use the smaller one for drilling.

[Mooseman]

Diamond drills...
I get them at jewelry supply stores and they come in 1mm,2mm,3mm etc. They look like a small mounted stone and you run them high speed thru the case hardened area, then you can drill with a normal HSS bit. They will also drill thru busted taps and drill bits.
Spot annealing works too but should be done on a raw receiver before it is blued if possible.

[220swiftfn]

Spot annealing with a soldering iron/drop of solder works. So does using a dental burr. Keep in mind that you can't just plow through, you have to go SLOW!!!! Drop the spindle speed down and he won't be burning out bits...


Dan

[HollowPoint]

I ran into the same problem a few years back when I decied to drill and tap my K31's receiver to accept a Lyman Peep-sight.

I've posted a discription of my ordeal before on this forum. I don't know if it will help but it may be good for a laugh.

The metal on my K31's receiver was so hard that none of my expensive drill bits would even put a scratch on the surface. I thought maybe if I held the rifle on my lap while attempting to drill my holes I could shuffle the rifle accordingly to keep my drill bit from wandering over the edge the receiver.

At one point it felt as though the cutting edge of the drill bit finall caught and was about to start drilling so I applied more downward pressure to get the drill bit to advance even further into the metal.

All I managed to do was to make the drill bit wander over the edge of the receiver and into the top of my thigh. The drill bit sunk into my thigh about an inch before I was able to stop myself.

The drill bit itself had been spinning on the surface of that hardened metal for so long before I applied the aforementioned pressure that it was searing-hot when it entered my thigh. It never did bleed so I'm assuming that the heat sort of corterized the wound; so to speak.

We learn these things the hard way. At least I do anyway.

I ended up posting an inquiry on the home gunsmithing forum and one of the guys there recommended I buy a Hi-Roc drill bit of the appropriate size.

I did so and it drilled through that hardened K31 receiver like it was hot butter. I then spot annealed the holes by sticking an old drill bit into the holes and aiming my torch-flame about an inch above the hole directly on the drill bit only. (not on the receiver)

The drill bit slowly became glowing hot at the point where the flame from the torch was hitting. That hot glow slowly worked it's way down the drill bit and into the immediate area of the hole that I'd just drilled. In short; I had just annealed the insides of the holes and nothing more. That's all I needed or wanted to do in order to tap the holes.

It was still hard to tap the holes even with the annealing. I used carbon taps just in case I broke one while threading those two holes. If I had broken a tap in one of the holes, I could have gotten the broken carbon tap out by chipping it out a little at time. The other types of taps may have been a little harder to get out.

HollowPoint

[HollowPoint]

OOPs. I double posted. My bad.

[Reg]

Sorry, but if he cannot drill and tap a standard M-98 Mauser receiver, I would question his ability. Period.

[TomBulls]

OOPs. I double posted. My bad.

The news so nice we print it twice! No worries, we've all had our own goof-ups on the board!

[shredder]

sorry, but if he cannot drill and tap a standard m-98 mauser receiver, i would question his ability. Period.

this!

[flounderman]

I haven't ran into a hard mauser. If that is a turkish mauser and he is using a wheeler jig, if he doesn't alter the guide lip it will obstruct the jig from lining up straight and the front holes will be off to the right. a diamond point in a dremel will cut the case hardening to where you can drill it with a normal bit.

[Dutchman]

Sorry, but if he cannot drill and tap a standard M-98 Mauser receiver, I would question his ability. Period.

+1000

[dragonrider]

Sorry, but if he cannot drill and tap a standard M-98 Mauser receiver, I would question his ability. Period.

Exactly, find another smith.

[Castlead]

Just the opinion of a machinist here - the dude dont know squat. Bring it somewhere else.

[TomBulls]

Thanks for the pro-tips. I'll figure something out.

[W.R.Buchanan]

I ran into this problem on my 03A3. After breaking several drills of increasing hardnesses, I used a small grinding point to drill thru the case hardening. Then it drilled thru just fine until it got to the inside of the receiver where I literally had to just shove the drill thru.

I then proceeded to break the same High Speed steel tap 4 times tapping the two holes.

This took 4 hours to accomplish on a hot summer day while sweating bullets (or Boolits as the case may be). I also did it on a Bridgeport mill so I could control everything that was happening to a high degree.

Spot annealing is the short answer, but you need to practice on a wasted receiver before you do it to something nice.

Better to let someone who knows exactly what they are doing do it. Doesn't sound like your guy does.

Randy