Scope base drill holes 0.450 apart?

Hi everyone,

I just acquired a customized small ring Mexican Mauser that's been drilled and tapped. Unfortunately, the mounts didn't come with the rifle. The front pair of holes are drilled in the standard Mauser pattern and a spare Mauser front base fits well. The rear pair appear to be slightly non-standard. My extra Leupold M98 two piece rear base has holes drilled about 0.500 apart. The rifle's holes appear to be drilled about 0.450 apart.

The online base charts put out by the major vendors are useless as they don't provide the distance between drill holes, yet I seem to recall having seen such a chart in the past. Can anyone point me to such a chart, or does anyone know for which rifle or make the 0.450 drill pattern is standard?

Thanks

If you discover the holes were tapped in the wrong place on the reciever you could have the scope base milled to fit. My one Rem 700 action had the forward most hole offset to the left (pitiful!) I milled out the base to match the holes in the action. If you don't have a machine shop near by, mail the base to me with measurements, and I'll mill it to your measurements.

I know a guy that has at least a half dozen rifles built on Mexican actions. I can check with him to see what his are. (shoot me a PM if you would like me to check) But, in all honesty, custom rifles can be drilled and tapped for any bases imaginable. If I were you, I would just take the rifle to Cabela's, BassPro, or Academy and try as many as you can find until you find one that works.

I have a bag full of weaver bases. I'll look through them and see if I can find one with the holes 0.450" apart and then cross reference it...unless the question is fully answered before I can get around to it.

I had a 1903 sporter once, I had to weld up one of the holes in a Redfield base, and match drill it to the receiver.

Not ideal, but not hard.

For the record, this is the chart that I had remembered seeing:

http://www.brownells.com/.aspx/lid=11214/GunTechdetail/W-R-Weaver-Company-Mount-Base-Specifications

Unfortunately, I don't see a 0.450 spacing.

Well...so much for a dead end idea.

I emailed Leopold technical support; with a little luck, someone will know something.

BTW, thanks for all the offers of help, everyone. I really appreciate it.

Then there is always the option of drilling an existing base to match, instead of altering the rifle. - Just a thought.

A one-pice base or picatinny rail would work for that.

I don't have a lot to add but I do remember that there was a different set of scope bases for the FN small ring Mauser and the sporterized 98. The Mexican Mauser is a small ring also which may be why the holes are .450 apart

While this is a zombie thread, it's worth mentioning that I finally discovered the answer to my question. The drill pattern was 0.436" inches apart. The pattern is from some old Mauser/M70 Weaver pivot mount bases, of all things.

Whoda thunk it?

So, how did you address the issue?

Cabela's only has the bases for FN Commercial Actions.

I am currently dealing with this. Small ring Mauser that no small or large ring bases will work with the spacing the receiver is drilled for. I am thinking someone had a spare base/bases laying around and drilled for them instead of the standard spacing.

I just bought a set of the discontinued Weaver pivot bases and rings.

We will see what we see.

I'd just buy a base and drill the holes where they needed to go.

There are already two holes drilled in the rear bridge, and it isn't all that big. Thus the effort spent finding an existing match.

Let me clarify: drill the necessary holes in the base, not the rifle.

Ah, that makes sense. I looked at the Leupold blank bases for just that reason, but the situation looked complicated. The bottoms of the bases have to match the contour of the bridge, the heights of front and rear must coincide, and the holes must be a good fit. The rifle, while nice enough, doesn't really warrant a significant $$ investment. When I found what appear to be the correct bases for about $20, I decided to go with quick and easy. The pivot mount/base combo appear to have been a marginal design from what I've read, but it's a low recoil rifle (7x57) and I think they'll be satisfactory.