Just need some guidance. I have a Japanese Arisaka type 38 that was drilled and tapped way before I ever got it. Unfortunately it wasn't drilled so that Weaver #70 1 piece base can be used. The holes were drilled in the wrong place. So I have been using straight tube scope(Weaver 1.5-4.5) but want to use a scope with more magnification. The problem is that most new scopes are not long enough in the body to fit between the 2 piece Weaver bases on now. I am scratching my head for ideas. Maybe get a gunsmith to make a 1 piece base? Any input is welcome.

If you want to use the Weaver #70, drill the base to match your existing holes; easier than drilling the receiver to match the base. I would do that.
Or get a one piece Weaver/Picatinny rail and fit it to the receiver and the holes you have; make it extend fore and aft to accommodate whatever scope you want.

Yep I wanted to drill the base to match the holes but the base is not long enough either front or back to be able to drill new holes to match the ones already in the receiver and the holes already drilled in the base. The rear receiver end also needs to be slightly shimmed as well.

You can buy blank base stock and drill it as you wish. Regards, Bill.

Hi Bill and thanks! Been googling these and there a million of them. I need one about 6" long. Can you recommend a good place to get one?

But don't forget you first have to machine the bottom to match your receiver ring and bridge contour; those blank bases are flat on the bottom. You will need a milling machine for that.

Many thanks for the help. Don't have a milling machine but will try to use an existing base and just drill new holes. Thanks again.

Weaver makes extension rings that can reduce the spacing by an inch. See Brownells number 955-490-450.

Bill Jacobs

The receiver contour of the Arisaka is very close to that of a Remington 700. I'd get a Picatinny rail for a 700 and go from there.

Adapt and overcome.

What weaver bases are are on it now ?

There is an OLD Weaver scope base list from the 1970"s that shows each base diameter, height and length.

I see the # 70 is for the Rem 600, is 5.90 " long has a diameter on the front of 1.290 " and a thickness of .275 "

J Wisner

Yes the #70 is what the Weaver chart calls for. However the receiver was not drilled so that this base will fit. The holes in the base don't line up anywhere close. I did drill one hole myself but I only have 2 holes that line up with holes in the receiver. I am not sure 2 holes would be enough for a scope mount to be strong enough. My gun is rechambered to 6.5/257 Roberts.

I had a Arisaka 38 with this same issue, holes drilled & threaded for who knows what sort of base.Plus IIRC one of them was off center.

This was back in the days before I'd never seen, much less heard of Picatinny rails, so I found a section of weaver rail that had a groove machined down the center of it and mounted that with JB Weld epoxy on everything including the screws. Afterwards I didn't like the lack of clearance under the scope for loading so I cut the center out of the rail which made it a bit easier.

Just went on ebay, it looked like this:


Just make your holes for the screws to go and cover the others with JB Weld! Needless to say that back then I was more concerned with things staying put and the gun had already had a tough life, if you want a quality rail Brownells has quite a few there and in steel in addition to aluminum, but as mentioned if one has a flat bottom you'll need the bottom contoured.

A Picatinny rail is nothing but a Weaver rail with specific notch dimensions and locations in it; "developed" by the small arms engineers at Picatinny Arsenal, ARDEC; I worked with them quite a lot, on Abrams Tank Armament. I mean the tank armament engineers, not small arms.
Everyone is a small arms expert; I wanted nothing to do with it.

Hey Mark, Thanks for the info. I am basically doing that now. I am experimenting with the #70 that is supposed to go on there. If it turns out well, will post a picture. f not, then I'll try something else.

I have used a weaver one piece rail for years. Two holes in the
reciever ring and one hole in the rear bridge. The Arisaka reciever
Ring is 1.340 and the Rem 700 is 1.360. .0020 difference is nothing to
be concerned with. Done deal.

Told ya.

I have used the B-Square one piece rail for the Mauser that has the notch to clear the charger clip hump on the rear ring with great success on many Arisaka's. I don't think they make it anymore, but you can find it on Ebay. Here's a pic of it:

https://www.midwayusa.com/prod...008810587?pid=576658

Here's a very similar EGW version currently made:

https://www.egwguns.com/scope-...ount-20-moa-military

Bases for the mausers will not fit correctly. The arisakas front receiver ring
and the rear bridge are the SAME diameter. If I remember correctly
I used the one piece rail for the old savage 110.