Adjust Euro side mounts - like on Swede or German sporter rifles

[Potashminer]

Hopefully this is the suitable forum for the question? Not so much about optics, but about mounting them on a rifle.

Picture below should show a side mount appartus for a German Mauser 98 - rifle is set up as a hunting gun - evidence suggests that it might be a "guild" sporter circa 1920's or so - so this is not a military side mount, but principles might be the same?? And I have no reason to believe that the rifle and this side mount came from the same era, but they came to me screwed together.



So, the front ring appears attached with a large screw up through the bottom, at the front. The rear ring appears to have an up/down dovetail and then a left/right dovetail - each with opposing screws to move the piece - then a larger screw to "lock in place" - I presume.

So my question - how is it possible to move a rear ring - left / right and or up / down - without bending the scope tube, if that front ring does not move? Maybe I have not figured out the installation sequence. Any advice is greatly appreciated for how these were meant to be installed and used.

 

[Potashminer]

Curiosity got the better of me - so I removed that front screw - appears that the front ring has a shoulder "spigot" that goes into a socket within the side rail - that would make sense to work with the left and right adjustment of the rear ring that is on a dovetail. But is also a vertical dovetail back there for up and down - can not figure out how that can be done without bending the scope tube??

 

[AP]

Many early European (German) scopes had provision for elevation adjustments (but NOT windage adjustments) within the scope tube… the base/mounting system provided windage adjustments … in your case if concerned about twisting the scope I would use a shim(s) on the base to achieve windage and then utilize the scopes elevation turret to zero

(Btw … unless the rear ring can move in an ARC when the front ring is rotated slightly left or right with the scope tube while adjusting the opposing screws bearing on the rear base … the scope will still be subject to some ‘bending’ .. although hopefully minuscule)

 

[Potashminer]

Yes. I have a 4x32 Hensoldt scope here that does not have a windage turret - only an elevation turret - so windage must be dealt with within the mounting system. But that sort of begs the question why this type of side mount would have a vertical dovetail for the rear ring, as if for elevation adjustment, but then has no obvious way - to me - for the front ring to respond to an elevation change made within the rear ring assembly??

Picture in Post #2 shows that spigot and socket of that front ring - seems to explain how the front ring can pivot in response to a windage change by the horizontal dovetail below the rear ring.

I looked in the "Crown Jewels" book - the short rail side mounts purchased from Germany and used on the Swede M41 sniper rifles appear to have a windage adjustment only - apparently it was these civilian type of mounts that also included an elevation adjustment - can be seen just in front of the rear ring in picture in Post #2 - I am not figuring out how that was supposed to work with that front ring installation, though...

 

[AP]

Picture in Post #2 shows that spigot and socket of that front ring - seems to explain how the front ring can pivot in response to a windage change by the horizontal dovetail below the rear ring.

understood … but even if the front ring pivots — it appears that the rear ring only moves laterally which will place the scope tube under tension when the rear ring is moved any appreciable distance.

as for the rear ‘elevation’ capability … I think it is best used simply to ensure that the scope is mounted with minimal vertical torsion on the tube … and not as the basis for making significant elevation adjustments …. There are European rings that can provide both (limited) windage and elevation adjustments without significant torsion applied to the scope tube …. EAW for example