Need M98 D&T advice

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  • Last Post 13 February 2014
tturner53 posted this 03 July 2012

I've had the good fortune of making a new friend who has a machine shop. Our first project is to drill and tap a Mauser 98 for a Redfield Jr. scope base, one piece. I ordered a tap and drill set from Midway, it turned out to be tapered. I'm doing this with the barrel on so need a 6-48 bottom tap to do the front holes. Here's my questions; where is a good place to get the tap? Anybody have a spare they want to sell? Would it be better to go with 8-40 screws instead? And, can the bolt be bent without using a real jig? Looks is not a high priority. Any advice would be appreciated as I am no machinist and the guy with the shop builds custom cars, not guns. He has a big lathe and a big vertical mill. I'm a gun plumbertinkerer but have always wanted to learn these basic skills. I have a few good books. Thanks  (The Redfield Jr. is the one with a flip up rear aperture sight, made for a 98).

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gnoahhh posted this 03 July 2012

One trick I have done is to take a starter tap and judiciously grind the tip off to continue threading to the bottom of the hole. When I say judiciously, I mean a little bit at a time continually quenching in water to keep it cool. If the tap changes color at the grinding interface, you're screwed as you have just taken the temper out of it. Needless to say, keep it square. I only did it when I was in a bind and couldn't wait for a proper bottoming tap to arrive. Worked well.

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raytear posted this 03 July 2012

tturner,

I have never actually bent the bolt handle for any Mausers I have owned--about 10. What I have done is to cut off the handle at the point where the stub will be flush with the outside of the receiver, saving the camming surface of the root. I use a Dremel for this with an abrasive wheel. Then I add some metal to the cut off end of the handle--ca. 3/16-1/4 inch. (For my taste, simply bending/forging leaves the handle a trifle short thus requiring more strength to open.) Next I reweld the handle to the stub remaining on the bolt. I usually put a downward and backward sweep/angle to it when doing so. Then simply dress the weld with files, emery cloth, and wet/dry sandpaper used wet.

It does require a heat sink and heat paste, and a “weld a bit, quench a bit” routine. Now, I do not do the welding myself since that is a skill I have not acquired. I engage the services of a welder or gunsmith with whom I have developed a relationship.  If using a welder, it is especially important to explain the need to avoid over-heating of the camming surfaces of the bolt.

For $14.95 plus shipping, last I saw, you can order a kit complete with a tap, a screw and a new, shaped handle. You cut off the existing bolt handle as described above, drill and tap the end of the stub. Then slip the new, turned down bolt handle over the stub and secure it with the screw.  Most any of the mail order gun supply houses carry this item. I have thought about ordering one to convert the straight handle on a particular rifle that has iron sights.  My local gunsmith had the bad form to die in his sleep a couple of weeks ago, so I'll need to groom a new welder.

You might also look at Jim Carmichael's Book of the Rifle. He shows a technique for dealing with military bolt handles in that volume.  Hope that is of some help.

Happy Independence Day and Good shooting! RT

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Reg posted this 03 July 2012

Drilling and tapping , as long as one is careful and follows basic machining techniques can be easily done. Bridgeport type mills are the best to use. Sweep the head, get on dead center and know where every screw is going to be. Do not split the inner locking area. Grind back another tap and make your own bottoming tap. The bolt handle is a cat of another color. It's one of those things that if you do not have a real good idea of what you are doing, take it to someone who does. A lot of guys will forge or weld on another handle and let you do the finish work. I sure have seen a lot of ruined bolts that were done by those who had good intentions but no ability. And yes, you can just buy another 98 bolt if yours gets messed up, they are cheap but------ then you have to refit the headspace and you still need to lower that bolt handle. Get it right the first time.

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raytear posted this 03 July 2012

Reg is all too right re: getting someone who knows what he is doing.  The only bolt I ever had ruined was by a “gunsmith” who made an extremely poor weld AND deformed the cocking cam in the bargain!  After some persuasion he purchased a new bolt. Happily when I checked the headspace myself, it was OK. That is a rare occurrance!

Happy Independence Day and good shooting! RT

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Ken Campbell Iowa posted this 03 July 2012

midway has bottoming taps ...order 2 or 3 then use your taper tap to start a thread or two, followed by the bottom tap

you could drill y tap the first hole, then attach the sight base, then use the base for the next guide hole...heh heh, yep it's cheating ...

a good body shop will have an experienced TIG welder guy...this is for delicate work, ....but do tell him about keeping things cool ken

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tturner53 posted this 03 July 2012

Thankyou all for the help. With what I've picked up here I feel confident to go forward, with the help of my new friend. He seems to know what he's doing, an old guy with a nice shop. He takes very ratty old cars and makes them into car show hot rods. Very meticulous, fabs up a lot of custom parts. He brought up having a heat sink paste before I had a chance to speak up about it. I'll order a couple bottom taps from Midway. Unfortunately this gun will not pass muster for a CBA match as it is a mix master 1912 Steyr 7.62 Nato but will look a lot like an old sniper rifle when I'm done. Replaced the issue front sight with a taller/wider one from Brownell's, notched the issue rear sight. I have a nice El Paso Weaver 6x to put on it when the work is done. In reading up I found the Army used Redfield Jr. bases on 03A4 sniper rifles, probably used the 6-48 screws too. Good enough for the Army, good enough for me.

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tturner53 posted this 03 July 2012

Thankyou all for the help. With what I've picked up here I feel confident to go forward, with the help of my new friend. He seems to know what he's doing, an old guy with a nice shop. He takes very ratty old cars and makes them into car show hot rods. Very meticulous, fabs up a lot of custom parts. He brought up having a heat sink paste before I had a chance to speak up about it. I'll order a couple bottom taps from Midway. Unfortunately this gun will not pass muster for a CBA match as it is a mix master 1912 Steyr 7.62 Nato but will look a lot like an old sniper rifle when I'm done. Replaced the issue front sight with a taller/wider one from Brownell's, notched the issue rear sight. I have a nice El Paso Weaver 6x to put on it when the work is done. In reading up I found the Army used Redfield Jr. bases on 03A4 sniper rifles, probably used the 6-48 screws too. Good enough for the Army, good enough for me.

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delmarskid1 posted this 04 July 2012

If your man can weld sheet metal a bolt will present no problems. Just remember not to cut the bolt off too short. You will need that material to cam open the bolt. I cut mine nearly through and them heated the area of the cut with a cutting torch set at a whisper. When it was showing a nice orange I tapped it down and back to where I thought it should be. Then I filled the open area with short but strong tacks with my wire feed welder. Not too hot, you will blow it up. Use a few No. 5 bolts to set the welder where you want it. After the welding is done heat the bolt handle with a little more heat and bend the curve into it. I did five or six of them on my lunch break when I was at work one night. I miss that work sometimes. I took a longish lunch some nights.

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Dale53 posted this 04 July 2012

Mauser 98's have an extremely hard case hardened surface. If you don't either grind through the case (spot grinding) or so some spot annealing you'll be breaking taps. That can be a REAL pain.

I was a teenager when all of those surplus 98's hit the market. Most of us had little real money so sporterizing military rifles was a popular item. I was in vocational high school machine shop. I took my Mauser to the shop turned a nice sporter taper on the barrel and drilled and tapped the receiver for a scope mount. I used an welding torch (very carefully) to spot anneal the receiver where I needed to drill it.

Worked like a charm...

The old gunsmithing books are full of information as to just how to do this.

Dale53

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delmarskid1 posted this 06 July 2012

Roy Dunlop mentioned spot annealing mausers in his gunsmithing book. It involved grounding the action and touching the areas to be tapped with a point attached to the positive battery lead.

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Ken Campbell Iowa posted this 06 July 2012

Roy Dunlop mentioned spot annealing mausers in his gunsmithing book. It involved grounding the action and touching the areas to be tapped with a point attached to the positive battery lead.


one such point can be made from the center graphite rod from a crushed old style   d   cell battery.......file/grind the point on one end, hook up 1 to 12 volts dc leads to the receiver and rod.    positive to the rod, so the “weld gunk ” will flow to the rod, not to the receiver.

neat old trick...we used these with a sharp point to burn part nos. into metal products.  work up on the supply voltage...dc, not mainline wall socket (g) ...

ken

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6mmintl posted this 11 February 2014

Mauser actions are case hardened, you will need to break thru case with a carbide drill/center drill/end mill in a ridged set up in a milling machine, or as ken mentioned spot anneal (battery/carbon rod) but you will have to deal with “Inside action case hardening (tap slowly) and try not to break tap.

Cut bolt handle off and Tig weld on a replacement, or forge/lengthen/thin existing bolt cutoff part to suit. Forging a bolt handle is not good for metal heat treating and distorts /softens cam/threaded areas.

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Larry Gibson posted this 12 February 2014

I've D&T'd many a Mauser action (M93, M95, M96 and M98s) and never had to grind through the case hardening or spot anneal to drill. They drill very easily. Perhaps someone is thinking of early M1903s? I also use a Forster jig to keep every thing lined up.

I suggest the OP use the Jr base as a guide to properly locate the holes. There should be a lip on the round bottom of the front of the base that sits on the front receiver ring. That lip should but up against the rear of the front receiver ring. That will locate the holes correctly front to rear. Set the action on a flat piece of bar stock and place the base on top of the receiver. Another flat piece of bar stock across the top flat of the base and the base slid left or right until the 2 bar stocks pieces are parallel. Now you have every thing lined up correctly to mark the holes. Center punch and drill using a good drill press or mill as suggested.

The front hole of the front base should go just to the depth of the screw and not into the barrel threads. The rear front hole can go through the receiver ring into the locking lug recess. That hole should not go into the receiver that buts against the locking lug. The rear hole at the rear goes through the rear receiver ring.

Use the tapered tap to thread the rear holes of both front and rear. Then start the threads in the front hole. Grind the tip of the tap off to where the threads just start to taper and finish the front hole with the “bottom” tap you have just made.

If you know how to forge a bolt handle and have the correct vise block, heat sink and torch you can easily forge the bolt handle w/o any problems. Trick is to know how to do it. With just the one bolt handle to lower best not to learn on that one. Cut of the handle and reweld on as mentioned.

LMG

Concealment is not cover.........

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tturner53 posted this 12 February 2014

I should have followed this up but it was too depressing. I'm ok now. The holes were not drilled exactly right as in do not line up correctly with the holes in the Jr. base. At that point I pulled the plug. When funds are available I will take it to a trusted gunsmith to finish the job. Right now I could mount the base if I altered it a tiny bit but lost confidence in original plan so did not even attempt to mess with the bolt. As is it's a real shooter and fun gun with iron sights.

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Ken Campbell Iowa posted this 13 February 2014

if you promise to only shoot mild/medium loads, you can use one good screw plus epoxy to glue the base( s ).

use good epoxy ..devcon, marine tex ... let cure for a week before shooting.

and yeah, it would be good if that one good screw was a #8 . and if the epoxied base is located ok, you could drill brand new holes thru it for new screws. then you could call that rifle ” Fugly ” .. ( g ) .

ken

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