Last updated 11.7.2010

Building a better mousetrap

Or...further study in concept, design and manufacture
of long eye relief scope mounts for vintage military rifles
and specifically
the German infantry Gewehr 1898 8x57mm

The wonderous Lange rear sight of the Gewehr 1898 Mauser

We are close to nirvana.... in so far as the Gewehr 1898 is concerned.

This NcStar 4x32 LER scope was the only one I had available to mount on this rifle. It will be exchanged for a new NcStar 2-7x32 LER scope shortly. The 4x32 scope is positioned as far back as it can go. You'll notice the adjustment turret is bumped up against the rear ring. It could stand to come back another 1/2" or so. The 2-7x32 is more forgiving.

Being that this is the first prototype it has rough spots and errors and places I intend on improving. But overall this is the most stable, strongest LER mount I've yet made. I'm very happy with where it is now and I'll be happier when it's where I want it. The mount will extend a bit further back towards the shooter about 1". There will be a 2nd ring clearance groove on the front part of the rail. And the final clamping rails will have 2 screws on each side instead of 3.

I was asked why not extend the rail back over the receiver as a cantilever mount for a conventional eye relief scope?

Several reasons. First these NcStar scopes have only 8 to 10 inches of eye relief as it is. That's not really "long" eye relief but intermediate eye relief. In comparing the eye relief of 8 to 10 inches with scopes that require much more eye relief you come away with a much better visual presentation when the scope is only 8 to 10 inches instead of 12-14-16 inches. The picture in the little round glass tube is just better at 8 to 10 inches. As it is there is very little handicap in using an LER scope with 8 to 10 inches of eye relief when compared with a conventional receiver-mounted scope.

A cantilever mount extending rearwards over the receiver would be higher than this mount. That's a negative integer in my book. Plus with unsupported rail you have flex. There is/are some such mounts that utilize a setscrew as a "leg" or support under this cantilever rail that bears on the receiver. I don't agree with that as a design feature as it bespeaks CHEAP and POOR. It also enables damage to the receiver crest of an in-the-white 100 year old rifle that could be worth $1,000 or more. Even using a brass-tipped screw is out of the question.

A conventional eye relief scope would then require some alteration of the bolt handle. That defeats the purpose of "doing no harm" to a valuable and collectible rifle. My design criteria was: as low as possible - extremely strong - extremely stable.

With some other LER mounts you can have: very low - very strong - somewhat stable. This is due to attachment limitations. This is where the Gewehr 98 stands head and shoulders above most all other military bolt action rifles.

I snagged this Lange sight one night on fleabay. Cost $20 + postage. These aren't so easy to come by anymore.

I disassembled it, cleaned it and inspected it. It's in nice condition. It'll be used in the shop to further develop the LER mount for the Gewehr 1898 German infantry rifle.

It's almost as if this rear sight was designed as an LER mount as a secondary use. The pin ears serve double duty to hold the base and act as the recoil shoulder.
What possible better anchoring method is there than these two grooves on each side of the base?

How can you weatherproof the underside of steel mounts and preserve your rifle's rear sight base trapped underneath the mount?

Lee Liquid Alox Cast Bullet Lube
White Label Lube (same as)

The only junk action I have in the shop disassembled is this Belgian FN Venezuelen Mauser. The only part that's salvagable is the bolt. With a new welded handle it'll go a hundred years in some custom rifle. I try and find a constructive use for the other parts like the barrel stub and receiver.

I used the receiver to make the precision arbor to face the front of the receiver. This arbor runs between centers and has less than .0005" run-out (half-thousandth).
It can also be run in a 11/16" collet. I need to make one of these arbors for the Swedish Mauser action as well.

This is the simple cut made to square the face of the action as part of the blueprinting process. Other steps will involve lapping of the inner torque shoulder and very lightly lapping the bolt lug races. This ratty old junk action will serve great purpose as a training aid. I really dislike making irreversable errors (oops!) on a good action.

So, I have a couple of the rear sight bases and elevation leafs for the FN Venezuelen Mauser. The barrel stub is a very convenient milling fixture for holding the rear sight base on the milling machine.

This is the elevation leaf. It has this round piece transecting the leaf. Its .151" diameter, close enough that a No. 24 drill rod could be used to fabricate a similar part without lathe turning as #24 is .152".

The elevation leaf slides back under this ledge and is kept firmly in place by the considerable pressure of the leaf spring (painful fingers will attest). The tiny pin that goes through that hole is there only in the event the elevator spring breaks. The tiny pin keeps the elevator from falling out of the rifle. Its a back-up retention design. The rifle's sights will function perfectly without that tiny pin.. until the elevator spring breaks.

This shows this ledge from the underside.

When the elevator spring is in place it can seem impossible to get the elevator to cooperate and slide into place. The failure to achieve this assembly can be the impetus for the creation of new profanity and new combinations of old profanity.

So, that explained everything didn't it? You understand perfectly and exactly how a new design long eye relief scope mount can be retained using the
existing technology of the original Mauser genius.

I believe the threaded hole should also be utilized simply because its right there and available. Its a M4x.7 thread so it can contribute some
substantial anchoring force when combined with two other means of anchoring a new design mount that I haven't quite illustrated yet... have I?

This design is an embryonic journey. It is my aim to perfect and refine designs until they peak. This mount design is going in a direction that LER mounts
for this type of Mauser base haven't taken yet. That's why it's being presented here as it unfolds and establishes prior art.

As well, I have a second (and third) design that anchors the LER mount in a completely different manner.
That one will remain incognito until the prototype is completed.

One of the major failings of cheap LER mounts is horizontal instability and way too much elevation adjustability as the byproduct of an imprudent design.
The use of one single attachment point with two or three strain screws simply cannot offer a stable platform for repeatable accuracy from a rifle.

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D.L.van den Brink
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