Drilling and tapping rifles - A few questions

[Dreamcast270mhz]

My father was looking at doing this to a few rifles as it doesn't look too hard but he does have some questions:

1. We don't have any sophisticated machinery to stop the bit from going too deep, what techniques can help prevent him from drilling too deep?

2. As far as mounting rifle scopes go, whats a good way to mark spots to drill?

He has prior experience with drilling wood, plastics and drilling some holes in steel, is anything else needed to attempt this?

 

[xr1200]

You really need a mill to do it right, there are some bolt on jigs made for military rifles, but its best left to an expert. Don't let any smith touch it unless they have a mill. A hack with a drill press will ruin the gun.

Most good smiths should do it for under $50

 

[HankC]

The hard part is making sure the holes line up to each other and to the centerline. Will be easier if he use a drill and tap fixture. What kind of rifles? Some rifle receivers are case hardened and you can use a grinding stone to break the skin then drill. Use a tape or even paint marker to mark the drill bit to prevent drilling too deep.

 

[Dreamcast270mhz]

He has a sporterized Carcano (it is a carbine), a hex receiver MN and possibly a mauser 98. I did mention the above poster who said leave it to the smith. He says he may just leave it to our local smith. Thanks for answering this guys, as I have no know-how on the subjects of metal working.

 

[rcmodel]

As already noted, without a drill & tap jig, a good drill press or mill, perhaps carbide drill bits, and some experiance tapping holes in very tough and/or hard steel with tiny little taps?

Don't even think about it!

One broken tap in a hole will cost you more in the long run to get it out and the hole fixed then just farming it out to a good gunsmith with the tools and experiance to get-R-done right the first time.

rc

 

[jimmyraythomason]

One broken tap in a hole will cost you more in the long run to get it out and the hole fixed then just farming it out to a good gunsmith with the tools and experiance to get-R-done right the first time.

It only takes one to take ALL the fun out of doing it yourself. Having said that though,I have D&Ted a lot of rifles (almost exclusively Mauser 98s) and have broken only one thread tap back in the late '70s. Let me say that without the proper broken tap removal tools it could have been a very bad day! I use the Forster jig and a drill press with excellent results.

 

[triggerman770]

D&T

quote"Don't let any smith touch it unless they have a mill. A hack with a drill press will ruin the gun."

a hack with a mill can also ruin the gun.
I have a drillpress and a milling machine, and do most of mine on the drill press
using my fixture. Mill set ups take a good bit of tome, and this has to be charged for,whereupon the customer generally has a fit, when he sees the bill.
but the gumsmith route is the "way to go"

 

[Jim K]

Gee, xr1200, I guess I was a hack. I drilled a lot of rifles using a drill press and a jig and I didn't ruin any of them. In fact, one of the ruined rifles I saw was drilled on a mill; the holes were straight, but about 5 degrees off center.

Jim

 

[Clark]

I have done dozens with a drill press and a drill and tap jig, after I already had a mill.

I do them all on the mill now. Things can go wrong with the jig.

 

[sniper5]

I do a bit of my own gunsmithing, but drilling and tapping is something I farm out even tho I have the tools (drill press, drills, taps including some plug and bottoming taps, know how to make alignment jigs, have an x-y table on the press) if I REALLY wanted to. The reason: If something goes wrong and I did it, I have to pay to get it fixed. If I farm it out and something goes wrong, the gunsmith has to pay to get it fixed. And in drilling and tapping there are thousands of things that can go wrong, and the receiver of a gun is not a place to make mistakes.

 

[Pokyman]

Drilling and tapping most receivers is not hard to do as long as you have the correct machinery and tools. If you don't have a drill jig to assure correct hole spacing or a milling machine and some experience you could end up being disappointed with the end result.
With the questions you have asked, I would recommend that you take the rifle to someone with the equipment and experience to do the job.

 

[Clark]

I have modified the drill and tap fixture so it will fit 1903 Turk high rear humps, and I have modified it so it will fit Mausers with the barrel still on.

I think the best way to do it is with barrel removed and in the mill.

Those sniper guys are hot for 8-40 threads, but I have never seen 6-48 strip out of anything but an Aluminum 10/22 receiver.

 

[gunplumber]

I would like to hear about drilling and tapping glass-hard receivers like the old Sav 99s and a bunch of milsurps out there......I have a method but it's complicated and takes time. What do some of you folks do?

 

[jimmyraythomason]

I D&Ted a Savage 99 several years ago. It wasn't one of the older ones,probably 1970s vintage. I don't remember having any particultar difficulty.

 

[Jim K]

There are extremely hard carbide drills and taps today that will cut into just about any receiver, but the old fashioned way was to spot anneal using a torch on very low flame, so you softened an area only about 1/4 inch in diameter which would be covered by the scope base.

Depth of hole doesn't matter a lot. For the holes in the rear ring and the rear one in the front ring, you can usually just drill through. You will have to clean out and maybe shorten the screws if there is any interference with the bolt. The front hole can be a problem as going too deep can cut through into the chamber, but the stop on the drill press prevents that. You might cut into the barrel threads a bit, but that is no problem because the screws are not long enough to go that far in, and in any case there would be a problem only if you tried to remove the barrel with a mount screw down in the hole.

Some gunsmiths will remove the barrel before drilling the front mount hole, but I never did; why take a chance in messing something else up just to be super fastidious?

All that being said, D&T a rifle for a scope is not (IMHO) a DIY job unless you are prepared to invest more money than a single job is worth.

Jim

 

[Clark]

gunplumber
I would like to hear about drilling and tapping glass-hard receivers like the old Sav 99s and a bunch of milsurps out there......I have a method but it's complicated and takes time. What do some of you folks do?

1918 Savage 99 take down 250-3000, I made another barrel for it in 6mmBR.

I just drilled and tapped it per the pattern of a more modern Sav99.

It was no harder than anything else.

I had to make some fixturing to get the tapered receiver in the mill vise. See the little pieces of Aluminum touching the receiver?

 

[gunplumber]

Thanks for your replies Jim and Clark. I apologize for not making myself more clear. I was wanting to know of your process for annealing the holes and the actual tapping. I have a mini mill and a larger Smithy as well as a Forster jig and extension. But I was wondering about your method for softening the hole itself to be able to tap. Do you use the washer and torch method (like Jim mentioned ) or some other? Breaking a tap off in a blind hole is not my idea of spending a pleasant afternoon. I use the hot sand method and was wondering if anyone had a little faster way. Thanks again.

 

[Clark]

I have drilled and tapped dozens and dozens of rifle and other holes and never seen a hard receiver, except maybe a 96 Swede Mauser, but maybe the tap was dull.

I have been drilling bigger holes in tool steel, 4140, which is what many gun parts that are to be hardened are made from. This can be a real pain. If the temp ever gets too high, the metal will harden, which makes the drill dull, which makes the metal hotter, and I get run away thermal feed back, resulting in a ruined drill and a very hard spot.

Then I have to throw away the drill and probably order a similar sized carbide drill to cut through the hard spot.

That is why the drill tip should always be drowning in coolant when drilling tool steel.

The #31 drill for 6-48 threads is so small, that the heat conducts away from the hole fast enough with a reasonable feed and speed. I still keep coolant on the #31 drill.

I use Kool Mist mixed 10:1 with water and sprayed from a plastic spray bottle onto the drill.

 

[Jim K]

Clark, maybe you are too young to have run into M1903's and M1903A3's. The latter are hard, but the former are really hard (RC 60-65 or thereabout). The average Mauser runs about RC 30-35.

Jim

 

[gunplumber]

The 03s, some Mex mausers and ANYTHING that says Eddystone on it are very hard. I use a carbide drill then turn down a small alum rod .5in long to heat with the torch to trans the heat to the hole; then I put a 5/8 nut with the bottom cut to fit the rec over the rod. When the rod and hole is heated enough I fill the nut with hot sand around the rod so cooling is slower. Then with lots of oil, air to clear chips and a new tap per each hole I can get the job done. I seldom break a tap anymore but darn the process is slow. Takes me about 2hrs to do 4 holes this way but it is the safest way I have found Thanks.