Mini-Mauser scope base adjustment

[DShortt]

I have a Zastava M85 I rebarreled to 300AAC. I'm shooting cast bullets from a Saeco #301 mould bore rider design. 207 grain.

It's a sub-sonic load, 9 grains of 4227 +/- a half grain. Still working up a load. Grouping is fairly decent at 1 1/2 MOA. I just wanted to punch paper and play with Cast bullets.

My question is, since they're so slow even at 100 yds I'm out of vertical adjustment. I have a Leupold one piece base on it currently. I was thinking about placing a shim under the rear mount and using JB weld to bed both mounting points to gain vertical adjustment.

Does this sound like a viable idea? And to get, say 20 MOA of adjustment how thick of a shim should I start with?

Any helpful suggestions will be most appreciated. You might not agree with my bullets selection and that's fine. As I said, this is just a paper puncher to fiddle around with Cast bullets.

Thanks for looking.

 

[boltfluter]

Personally I would buy a new mount. If you shim the existing one, the screw holes are now tilted and the screws will not seat correctly. Just my 2 cents.
Paul

 

[AlNyhus]

You'd be better served with Burris Signature rings and the offset inserts....just my 2 cents worth.

So...you must have gotten the light primer hit issue sorted out?

 

[DShortt]

You'd be better served with Burris Signature rings and the offset inserts....just my 2 cents worth.

So...you must have gotten the light primer hit issue sorted out?

Not exactly. I'm still trying to figure out if it's the bolt rotation or the bolt hood. Next range trip I'm going to take a small piece if shim stock and place it between the receiver and the hood on one side. Then I think I'll be able to determine the exact cause.

I like your Signature Ring suggestion. I don't think elevated bases are available for these? The Signature rings ..... I've never tried them. Do you think I can get 20 MOA out of them?

 

[DShortt]

Personally I would buy a new mount. If you shim the existing one, the screw holes are now tilted and the screws will not seat correctly. Just my 2 cents.
Paul

Good point. Problem is unless I'm mistaken an elevated base isn't available for these?

 

[Jonnyofalltrades]

20 MOA is 1/3 of a degree. If you take tan0.3333 you get about 0.0058" per inch of base spacing.
Nothing against Burris Posi-Align rings, they're great. But just shim it and put the $70 towards making a lot more great plinking ammo. Just my 2 cents.
Sounds like a fun gun. Can?

 

[DShortt]

20 MOA is 1/3 of a degree. If you take tan0.3333 you get about 0.0058" per inch of base spacing.
Nothing against Burris Posi-Align rings, they're great. But just shim it and put the $70 towards making a lot more great plinking ammo. Just my 2 cents.
Sounds like a fun gun. Can?

No, not yet at least. I've thought about one and I might decide to get one yet.

This thing would be quiet as a slingshot with a can.

 

[Jonnyofalltrades]

Waaaay too much fun!

 

[Ggmac]

I have the formula, but will need to find the book . I shimmed mauser bases dozens of times in the early 70s . Do exactly as you said , I used Jb weld wirh Brownells shim kit .

 

[Ggmac]

I have a Zastava M85 I rebarreled to 300AAC. I'm shooting cast bullets from a Saeco #301 mould bore rider design. 207 grain.

It's a sub-sonic load, 9 grains of 4227 +/- a half grain. Still working up a load. Grouping is fairly decent at 1 1/2 MOA. I just wanted to punch paper and play with Cast bullets.

My question is, since they're so slow even at 100 yds I'm out of vertical adjustment. I have a Leupold one piece base on it currently. I was thinking about placing a shim under the rear mount and using JB weld to bed both mounting points to gain vertical adjustment.

Does this sound like a viable idea? And to get, say 20 MOA of adjustment how thick of a shim should I start with?

Any helpful suggestions will be most appreciated. You might not agree with my bullets selection and that's fine. As I said, this is just a paper puncher to fiddle around with Cast bullets.

Thanks for looking.

Amazon has a set of rings I’ve used before , they adjust one ring for height and the other ring is a pivot that tightens . They’re $26 . They work as is but can be made more solid .

 

[AlNyhus]

I like your Signature Ring suggestion. I don't think elevated bases are available for these? The Signature rings ..... I've never tried them. Do you think I can get 20 MOA out of them?

With the offset insert kit, you can get up to 40.

 

[DShortt]

Fellas, I just realized that the Leupold base has the twist-lock rings so unless I buy a different base adjustable rings won't be helpful.

I think I'm going to go back to a shim and JB Weld. In order to correct for the offset angle in the screw/base relationship boltfluter mentioned I plan to bed the base first, then once that has set add just a bit of JB to the bottom of the screw holes in the base so the mating surface will be flat.

Pretty sure there are a whole bunch of bases mounted with far worse alignment problems that have lock-tite on the screws because they kept working loose. Learned that the hard way myself.

 

[AlNyhus]

Fellas, I just realized that the Leupold base has the twist-lock rings so unless I buy a different base adjustable rings won't be helpful.

The Burris Signature rings are available in the dovetails, standard and Weaver style bases (Burris' Zee style).

FWIW, my Mini Mark X needed to have the rear base raised about .018 to be level with the front base (Weaver two piece bases). After using a bit of solder to establish the height, a dab of Pro Bed on the rear base established the correct level. After that dried, the solder was removed, and it was final bedded.