MOUNTING MODERN SCOPES ON LYMAN/UNERTL TYPE SCOPE BLOCKS

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  • Last Post 15 February 2020
joeb33050 posted this 14 February 2020

 

MOUNTING MODERN SCOPES ON LYMAN/UNERTL TYPE SCOPE BLOCKS

 Many single-shot rifles, and many older 22 rimfire target rifles have, or at least are drilled and tapped for, Unertl/Lyman/Fecker style scope blocks. (See http://www.steveearleproducts.com/ for scope block information.)

 

We sometimes want to mount a Modern, internally adjustable scope on one of these rifles, without drilling any additional holes in the barrel or action.

 

“frnkeore” on the ASSRA forum makes adapters that goes from SCOPE BLOCKS to modern scope mounts.

 

Some 22 rifles and air rifles are made with 3/8” / 11MM dovetails in the receiver, for mounting sights.

 

(Some dovetails are called 3/8”, some are called “11MM”; my experience is that all 3/8” and 11MM items are interchangeable. 3/8” rings fie 11MM dovetails.)  

 

An example is this Mossberg rifle:

Go to AMAZON, search on DOVETAIL SCOPE RINGS.

 

Scope Rings are made to fit this dovetail and mount scopes, and it so happens that rings that fit the dovetails also.

fit scope blocks. Here’s a set of dovetail 1” rings:

 

Here is a Martini 30-30 rifle with a modern scope / dovetail ring. I shot this rifle/ several scopes for thousands of rounds with lower-velocity cast bullets, and never had a problem with the scope or ring becoming loose or damaged. (I used a Weaver T36 scope among others.) I also never had a problem with zero shifting.

 

Obviously, the scope cannot be mounted with two rings above the two scope blocks and be able to see through the scope.

 

There are two problems with this scope mounting method.

 

First is the “wince” problem; most people wince when they see the rifle/scope for the first time. People are anti-cantilever.

 

Second is the “zero shift” problem; if the scope is removed and replaced, the zero shifts. I have never figured out a procedure that reliably shifts the zero less than about 4 moa. If I leave the scope on the rifle, then there is no zero shift.

Go to AMAZON, search on DOVETAIL TO PICCATINNY ADAPTERS.

 

There are two mounting systems, WEAVER and PICATINNY. Anything that fits a WEAVER mount will fit a PICATINNY mount. BUT. My T36-XR Weaver, mounted on a PICATINNY mount, will not fit on a WEAVER mount, it’s about ring spacing on the scope/slot spacing on the mount. Adjust one ring a smidgn, or a smidgn of file work on the mount, and it fits.)

Here’s a dovetail to picatinny adapter, that will clamp on the scope block and fit standard scope rings. With these adapters, scopes can be removed and replaced without a zero shift, so that problem is solved.

 

However, while two rings can be used, both must be ahead of the turret for proper eye relief.

 

Martini: 

 

M52 Winchester:

 

 

The use of two rings lessens the “wince” problem, but getting one ring behind the turret would eliminate it.

 

 

 

Go to AMAZON, search on OFFSET SCOPE RINGS.

 

Offset rings get the rear ring behind the turret.

 

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GBertolet posted this 14 February 2020

EGW makes some cantilever mounts for specific rimfire rifles, that use the rear scope block mount. I recently saw their special sale on the Win 52/75 mount.

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Bud Hyett posted this 14 February 2020

Frank Elliott in Southern Oregon makes the mount shown below. I use them on my CPA Stevens 44 1/2 since I can switch barrels easily from .32-2 to .25-20 without totally losing the zero on the target. They will be on the paper after the barrel switch;

Although one rifle shoots into the extreme lower right corner or extreme upper left corner depending on the switch. This is within the correction ability of the scopes. The other rifle shoots within several inches high and either right or left depending on the barrel switch. Both are within the correction ability of the scopes. 

The one disadvantage is the scopes sit slightly higher and the need on one rifle to use a strap-on cheekpiece to get up to the centerline of the scope. 

This also fits the need for an easy way to move from Internal Adjustment to External Adjustment scope for matches requiring external adjustment scopes. 

Farm boy from Illinois, living in the magical Pacific Northwest

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RicinYakima posted this 14 February 2020

I bought one from Frank last year, and it has been a great. My 40/50 Sharps Straight kicks hard enough to bad things to the old scopes. Now I can use a current scope and not worry about my originals.

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Ken Campbell Iowa posted this 14 February 2020

thanks guys.  these gadgets could save us a lot of hassle occasionally ...

hey Bud ... ever try angling your crown to bring those groups on your switch barrel back to a more common zero ? ....

ken

 

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Bud Hyett posted this 15 February 2020

Hey Bud ... ever try angling your crown to bring those groups on your switch barrel back to a more common zero?

140 shots this Wednesday testing a load and trying to regain some competency for the coming year.

First test was for the scope and its ability to hold zero. Found the scope needs five shots after adjustment to center and hold. I have long suspected this scope needing more shots to center and hold the adjustment.

Second test was to see where the rifle shot after cleaning. Twenty-five shot groups were shot and the rifle went 75 rounds before the groups went wild. Twenty-one out of twenty-five shots in the third group went sub-minute, three were out due to cracked necks and one was out when I steered the rifle with the trigger. 

I am not messing with the physical makeup of the rifle after that grouping, I will try to earn to live with its idiosyncrasies.

 

 

Farm boy from Illinois, living in the magical Pacific Northwest

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joeb33050 posted this 15 February 2020

Frank Elliott in Southern Oregon makes the mount shown below. I use them on my CPA Stevens 44 1/2 since I can switch barrels easily from .32-2 to .25-20 without totally losing the zero on the target. They will be on the paper after the barrel switch;

He is the person I referred to as “frnkeore” on the ASSRA forum makes adapters that goes from SCOPE BLOCKS to modern scope mounts. I didn't have/find a picture of his adapter.

Frank's adapter is $110. Dovetail scope rings at $9.99, or an adapter at $8 or so will do the same job, I have used a ring for many rimfire and 30-30 cf cb shots.

 For any heavy-recoiling rifle, Frank's adapter is a better choice. 

Steve Earl put blocks on a rifle for me with 8-40? rather than 6-48? screws, also a stronger choice.

All that said, I have never seen or heard of a scope block breaking free, breaking screws.

 

 

Although one rifle shoots into the extreme lower right corner or extreme upper left corner depending on the switch. This is within the correction ability of the scopes. The other rifle shoots within several inches high and either right or left depending on the barrel switch. Both are within the correction ability of the scopes. 

The one disadvantage is the scopes sit slightly higher and the need on one rifle to use a strap-on cheekpiece to get up to the centerline of the scope. 

This also fits the need for an easy way to move from Internal Adjustment to External Adjustment scope for matches requiring external adjustment scopes. 

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  • Bud Hyett
joeb33050 posted this 15 February 2020

EGW makes some cantilever mounts for specific rimfire rifles, that use the rear scope block mount. I recently saw their special sale on the Win 52/75 mount.

I CAN'T FIND SUCH IN THE EGW CATALOG, AND WOULD LIKE TO FIND THIS SOURCE. ANY MORE INFO?

Thanks;

joe b.

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Bud Hyett posted this 15 February 2020

Joe B. - The reason I use a stronger adaptor is that I have had a scope come off the barrel. Unusual case possibly, but this made me paranoid. 

Mounting a K4 Weaver with the Davis Long Eye Relief Adapter on a Ruger .30 Carbine Blackhawk. We drilled and tapped the barrel for Unertl bases using Weaver .22 Rimfire rings to have a scope for shooting beyond 50 yards. This was in the mid-1970's before the many scope mounting systems came out.

First shot and the scope was in the air when the rings let loose. Possibly the weight of the scope with adaptor with the leverage of the weight in recoil exceeded the ability of the rings to hold. Anyway, the man next to me caught the scope in mid-air and the scope was saved.

A year or so later, Weaver came out with a good scope mount for this rig and I bought one. The rig was cumbersome, but good for keeping around the farm for stray dogs, they would instantly run at first sight if you had a rifle or shotgun. 

I used Herco and a cast 110 grain tapered flat-nosed bullet. The load was good on any dog up to big German Shepherd size, they took several shots to bring down.

Farm boy from Illinois, living in the magical Pacific Northwest

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