Long Eye Relief
Scope Mounts
For Vintage Military Rifles
A Study in Concept, Design and Manufacture
Feb. 11, 2008
1908 Brazilian Mauser
There are some commerically available LER mounts in the marketplace. S&K Like:
Ok, so I can't count. Still, even with out of balance likes versus dislikes I think the S&K mounts
And then there's the B-Square-------
Return to index © 2008
See further down the page for a synopsis of commercially available LER mounts.
A high percentage of milsurp collectors and shooters are now older and afflicted with the universal fuzzy eye syndrom.
We like shooting but can't see the sights so well anymore.
The second group are those who enjoy hunting with their collectable military rifle but find the sights aren't calibrated or
otherwise suited to hunting. Many rifles, as with the 1896 Swedish Mauser, are calibrated to zero at 300 meters rendering them
fairly useless unless changed or otherwise modified. The object of this discussion centers around mounting optical sights to
collectable rifles without modifying or permenently altering them and damaging their future collectability and monetary value.
The mount on this 1896 Swedish Mauser represents my 3rd alteration. It succeeded in some features and failed at others.
As it was my first attempt I did drill out the rear sight base setscrew to a larger size.
This violated my first rule of LER design criteria:
This mount did succeed with two of the four rules in that its as low as you can go and its steel.
Where it fails is in not having adequate eye relief adjustment. It works fine with the Tasco 3x28 scope but does not
allow enough rearward adjustment when the NcStar 4x32 is mounted. I did shoot an exceptional group with cast bullets
using the NcStar 4x32 scope but had to "choke up" on the stock to get a repeatable sight picture, and that repeatable sight
picture is absolutely nessessary for repeat shot accuracy.
For some time I've had a minor case of obsessive interest in LER scope mounts for several vintage military rifles in my collection.
Some rifles are more accurate than others and its those rifles that provide the most satisfaction in developing LER scope mounts for.
The Finn m/39 Mosin-Nagant rifle was my 2nd attempt at a LER mount. The m/39 represents a superior platform
to the Swedish m/96 in that the ladder pin is 4mm to the Swede's 3mm and the rear sight base setscrew is M4 to
the Swede's M3. Its just a broader and larger platform overall.
Many, not all, but many vintage military rifles have a setscrew that holds the rear sight base in place to locate
it for the soldering at the arsenal or factory. Soft solder is used, not silver solder as many assume. Many times the
base of this setscrew becomes soldered during the process rendering easy removeal very difficult unless heat is applied
just enough to melt the solder and allow the setscrew to be removed. Too much heat and two negative results can happen:
1- some solder can bubble up around the rear sight base.
2- the bore can shrink if overheated by anything but a propane torch.
Do not ever used oxygen-acetylene on soft solder on any barrel. It is fully capable of shrinking the bore dimensions
underneath the rear sight base. I've seen it and I have a sample in a 1895 Chilean Mauser 7.62mm Nato conversion.
This mount is quite good in design and function, though it doesn't allow enough rearward eye relief adjustment. It can also
be made lower by 3/16" to 5/16" by moving the front cross-cut back to clear the front ladder pin "ears" so the whole Weaver
rail could be lowered. See the yellow line in the front and red in the rear representing where the mount should extend to.
There is some limitation as to how low a position can be attained with some rifles, such as the Finn m/39, due simply to rear sight
design. Still, the 2nd effort at this Finn m/39 mount will be both lower and a longer mount to allow more eye relief adjustment and
more ring recoil shoulders milled in. The attachment is utterly simple and extremely strong as it is.
Along comes the German World War 2 K98k 8x57mm rifle. And with it comes one of a few rifles better suited than
most for mounting a LER scope mount. Why? The absense of any handguard between the rear sight base and receiver
allows a much lower scope position than those rifles with a tall hump of wood getting in the way.
This mount is a work in progress as it has yet to have the attaching screws machined in place. The Weaver rail
is 5 inches long and allows an entirely adequate eye relief adjustment forward and back. It may yet be lowered more
but not more than .050" between the base insert and Weaver rail. Its a two-piece design with the Weaver rail attached
to the base insert via screws. This allows some latitude in design and attachment. This will be one very cool mount.
You may notice a less than uniform spacing of the recoil shoulder cross-cuts. With prototypes there's a certain amount
of ~eyeballing~. What we don't measure we fake.
This is how the K98k mount started out.
Then this. Things change during the initial machining process, ideas formulate and
visions ferment.
The K98k and some few other 98 models such as the Czech Persian 98/29 have what is known as a removeable tangent bed rear sight.
The tangent bed was removeable so the rear sight could be calibrated for different ammunition. By removing the tangent bed
we're presented with a slightly superior base to design an LER mount.
This shows the tangent bed in place. That screw on the far right is a sort of clamp screw that helps hold the tangent bed in place.
It is fit rather tightly but comes out without too much ado.
(See further below for examples of rifles with non-removeable tangent rear sight bases)
Another one of the more suitable rifles for a low LER mount is the Gewehr 1898, the original 1898 Mauser military model of
Germany in caliber 8x57mm. Some models of 1891 and 1909 for Peru and Argentina also have this type of rear sight.
Isn't this a nice large mounting platform? A pin hole location in the ladder ears and grooves running down each side of the flat base.
At present it appears rather large and ugly but things will change as that
design vision ferments.
This particular Gewehr 98 is a bit raggidy. It spent considerable time in Turkey after
World War 1. Its a Mauser Oberndorf dated 1917. Not pretty but it serves as a fine shop
rifle and range rifle.
Some 98 Mausers with non-removeable tangent base rear sights:
1909 Argentine Mauser
Czech 98/22
...and many others
This is a 1908 Brazilian Mauser caliber 7x57mm. The tangent curve is built into the rear sight base.
This type of rear sight base presents a different design criteria than the K98k or other rifles.
The 1909 Argentine Mauser caliber 7.65x53mm is nearly identical to the 1908 Brazilian with the exception of this little
square elevator lock,
chipped on this example below:
Dimensionally it is not exactly the same but close enough for designing similar mounts.
These 1908 and 1909 rear sight bases are very common
among 98 Mauser contract rifles.
Moving into an area of entirely different rear sight base design are the following:
German Commission Gewehr 1888
With the ladder upright....
1893 DWM South African-Chilean 7x57mm.
This particular Mauser rear sight is shared with the 1891 Argentine and 1895 Chilean Mauser.
When in the down position the elevator slides to the top of the ladder and locks into a dovetail
located integral with the ladder spring. This leaves the two edges of the ladder with a perfectly
functional clamping surface about 1.8" long. It'll take a prototype to determine if this method of
attachment is adequate. The German Commission 1888 and the Japanese Type 99 don't have a
similar ladder locking feature.
...and with the ladder upright.
Japanese Arisaka Type 99 caliber 7.7x58mm.
... and with the ladder upright.
The 1888, 1891, 1893, 1895, 1908, 1909 and Type 99 require a different achoring method in
what I term a "top hat" anchor...
...because it looks like a top hat!
Doesn't it?
It slides into the thin groove intended for the elevator spring and is held in place by a setscrew.
Shown is the 1908 Brazilian rifle 7x57.
This is the base type of the Gewehr 1888, 1891, 1893, 1895 & Type 99 rifles shown above.
Darrell's Scout Mounts, S&K and B-Square are the primary players.
Darrell has designed and supplies LER mounts for several vintage military rifles.
Shown there is a Swiss K31 with a very popular mount.
All photos of Darrell's mounts are used with permission:m39scout at bellsouth.net
The K31 mount.
Another very popular model by Darrell is this one for the m/39 Finn Mosin-Nagant
7.62x54R rifle.
The Russian/Soviet 1891/30 Mosin-Nagant rifle.
A closer view of the 1891/30 Russian Mosin-Nagant mount.
Darrell also markets a mount for the m/44 Mosin-Nagant carbine.
In corresponding with Darrell he offered these insights into the design and construction
of his LER mounts:
1 - My mounts are machined from solid billet, high strength, aircraft aluminum alloy. They are then black matte anodized.
The alloy that I use has a yield strength (40Kpsi) that is higher than that of standard low carbon steel (26Kpsi-32Kpsi),
and it only weighs about 1/3 of what it would weigh if made from steel. This gives it a tremendously good strength to weight
ratio, and allows for adding some extra "beef" to the mount, while keeping it light. The anodizing also adds some scratch
resistance and surface toughness to the mount. This is the THE BEST material for the job and any other material would only
be heavier and/or much more expensive without improving real world performance.
2 - I supply brass setscrew with my mounts, because 99% of my customers are collectors that do not want to permanently dimple,
scratch, damage or alter their C&R firearms in any way. However, if one is not concerned with scratching or dimpling the finish
and needs a little "feel good" insurance, then one can certainly substitute steel screws for the brass, by going to Home Depot,
Lowes, etc. to purchase replacement steel screws; however, that really is unnecessary.
2a - The screws work together as a system. The front and rear elevation screws account for virtually all of the holding power
to lock and bind the mount in place. The 4 side clamping screws act as stabilizers and force multipliers to improve the
holding power of the elevation screws.
2b - I supply a replacement pivot pin (roll-pin), but that is just for completion or "spare". You can use your original
pivot pin with no problem.
3 - The Weaver rail is machined into the mount. There are no windage adjustments in the mount, but, I have never needed
such a feature, and my scopes have always had more than enough windage adjustment to take care of my needs.
4 - I send complete instructions and a drawing for installation and initial alignment. When the mounts are installed
according to my instructions, they are rock solid, and no problems with them coming loose.
My own obervation of Darrell's mounts:
Since Darrell first began marketing this LER design I've watched and listened to his customer's feedback. Its one
thing to hawk your own goods but the real meat 'n' taters comes from the users of the product. In this regard I've
not ever heard or read of one complaint about Darrell's LER mounts. That fact got my attention. At present I don't
own any of Darrell's mounts so my entire opinion is based upon customer feedback and my own observation of the mounts
themselves. I'm keenly interested in LER mounts so those that succeed I tend to pay attention to. I do plan on
purchasing two of Darrell's mounts. One for the K31 Swiss and the other for the Russian 91/30 as I don't intend
on designing mounts for those myself.
This is a Swedish m/96 with an S&K LER mount.
It attaches with the same "top hat" anchor as above.
I've recommended the S&K when I've received queries about a LER mount for the m/96 rifle.
I like the S&K for two reasons and dislike it for two reasons.
Dislike:
are the best that we have available to us commercially for the m/96 Swedish Mauser and I'll continue
recommending them for certain models of rifles. Some of the S&K mounts I just don't like for design reasons.
I'll have more to say about this thoughout the summer of 2008.
The B-Square on the m/96 Swedish Mauser 6.5x55.
The screw to the far right is a strain screw.
The B-Square clamps around the ladder and then uses a strain screw to push upwards and hold the mount
in place. Its adequate... barely. There have been B-Square used on hunting rifles with great success.
Of this I won't dispute. But the B-Square is an inexpensive solution to a problem that needs a little more
attention to sound design principles, not to mention stronger attachment methods. But it'll put meat in the pot.
Meat in the pot with B-Square.
My scope mount making machine is this Index Model 40H vertical milling machine.
Built in 1942 for Douglas Aircraft in Long Beach, California for US Navy aviation.
It has a #9 Brown & Sharp spindle, 8x28" table, weighs 1,200 lbs and is entirely
adequate and accurate for a home shop. I've owned it 25 years.
swede1894@gmail.com
D.L.van den Brink
~Dutchman~
No photos or text may be copied
or used without written permission