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Military Firearm Restoration Corner

Drill & Tap Job


Clemson

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I am sure this has been done, but I took pictures while I worked on a Mauser receiver today. This receiver is from a Yugo M48. The barrel was toast, but the rest of the receiver is in pretty good condition.

 

DTMauser002.jpg

 

I am using a jig that I bought from Midway many years ago. It is not a Forster, but it does OK on Mausers. Here is the receiver mounted and sitting on the table of my milling machine. Note that there is a set screw that butts up to the front ring. That sets the spacing of the holes in the fore and aft direction. The rod down the center of the receiver sets the side to side spacing.

 

DTMauser004.jpg

 

The jig comes with bushings for the #31 drill that is the correct tap drill for a 6x48 hole. I ALWAYS use a new drill and a new tap for each receiver. I buy them in 5-packs from Brownells. The drill goes all the way through both the ring and the bridge. The hole locations are set so that the drill penetrates the "safe" zone in the receiver ring.

 

DTMauser007.jpg

 

The tap bushing is inserted after the drilling is done. I moved the receiver to the bench vise for this step.

 

DTMauser010.jpg

 

The reason for the Brownells carbon steel taps became apparent to me on the third hole. I broke a tap! After uttering an oath, I used a prick punch to break up a fair amount of it, then I drilled on it with a 7/64 carbide drill, then I used the prick punch again to break the remnant out of the hole. If you are going to drill & tap receivers, you are going to break a tap, sooner or later. Be prepared.

 

After finishing the tapping, I tried my one-piece Leupold mount.

 

DTMauser012.jpg

 

Here is the mount installed.

 

DTMauser014.jpg

 

If I can do it, you can do it!

 

Clemson

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GREAT TUTORIAL......Just one question. I have the same jig, and I used it to mount an FN base to my mauser that the hump was removed, and it was a half a hole off. Will the jig work for over the hump mount? I thought the hole spacing was the same on both types of mounts. Or did you move the jig back after you drilled the first holes?

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GREAT TUTORIAL......Just one question. I have the same jig, and I used it to mount an FN base to my mauser that the hump was removed, and it was a half a hole off. Will the jig work for over the hump mount? I thought the hole spacing was the same on both types of mounts. Or did you move the jig back after you drilled the first holes?

If I read you correctly.. [assume] you are referring to the difference in the leupold mount, between the FN mount and the "military" mount! The darn holes are different spacing for the rear mount!! Why? I don't have a clue! Call me "Confused-ious"

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The spacing on this jig works fine for all three holes. I did not move or reset the jig for the rear hole. This particular Leupold mount is for a Mauser with the charger hump still intact. I have run into a problem with a mount that JBird brought over. We drilled and tapped before trying the mount, and it is off by about that half hole. Now that my mill is running, I need to remember to have him bring the mount over so we can fix it.

 

Clemson

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If I read you correctly.. [assume] you are referring to the difference in the leupold mount, between the FN mount and the "military" mount! The darn holes are different spacing for the rear mount!! Why? I don't have a clue! Call me "Confused-ious"

It's because the military mount is design to use without removing the charging hump. With a srardard hole spacing you would run out of metal when you postion the first hole back enough to clear the hump. You can ust the jig for those to but it takes some carefull measuring and reposition the jig 3 times, once for the front mount, and once for each of the rear holes. But the jig will make sure the 4 holes are in line with each other, but you have to make sure of the spacing.

-Don

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I ALWAYS use a new drill and a new tap for each receiver.

Great tutorial! I try to save the bag all my taps (any size) come in. I write on the bag with a sharpie how many holes in what material. I use new ones for things like receivers, and use the once used on non critical jobs, or thin soft materials.

Good job, thanks for showing us Clemson!

-Don

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  • 3 weeks later...
I could probably sell my used drills and taps on evilbay, but they might get purchased by the guys around here, and I couldn't live with myself then!

 

Clemson :P

Thanks!!! MV

But if you use yer "regular" handle... we will figger it out!!! [i'm not likely to buy something like a tap "online"!!!]

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I have a fixture like that I got 6 years ago.

I have done ~50 Mausers on it and a few Arisakas and other things.

 

I have also drilled and tapped on the milling machine.

 

The fixture is much easier.

Harder to make a mistake with that fixture.

 

If the tapping gets hard, get a sharper tap.

Don't break one off in a receiver.

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clemson the reason your mount if it was a b square 1 piece was off is because they're was a batch miss drilled i had a dozen i had to send back.also i have a wheeler jig and i had to notch the front pillar for the k kale to square up.finally on the wheeler jig if your doing arisaka the jig i got,the hole pattern doesnt match up to any mount.thanks keep up the good work on these help sessions.

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clemson the reason your mount if it was a b square 1 piece was off is because they're was a batch miss drilled i had a dozen i had to send back.also i have a wheeler jig and i had to notch the front pillar for the k kale to square up.finally on the wheeler jig if your doing arisaka the jig i got,the hole pattern doesnt match up to any mount.thanks keep up the good work on these help sessions.

 

It may well have been a B-square mount. It was engraved, as best I can remember.

 

Clemson

 

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