Technologist
Well-Known Member
I have an old Sako M98 built on a civilian production FN reveiver. The screws for the two piece bases broke (I think it was the forward ones but I don't remember) a long time ago. I've finally received the replacements in the mail but I wonder, how was this ever a good setup?
The two scope bases are mounted on a surface that as far as I know was never intended to be used as a platform for mounting optics. What are the tolerances as far as parallelity of the forward and rear reveiver rings? There is nothing ensuring the alignment of the bases as they are screwed to the receiver, except a minute cone shape on the bottom of the screw heads. In most other applications one would have added guide pins (two per base) to ensure that the bases go on straight relative to each other.
In our days of mil/mil scopes, full length top rails and very accurate factory rifles, we take scope mounting for granted.
How do I put the bases back on the rifle the best way? I know a lot of people recommend just screwing them on there and then grinding the scope rings with a kit. It seems backwards to me to correct the scope rings, that most likely, since they were actually designed to hold a scope of a specified diameter, have tighter tolerances than the surfaces on the receiver.
Is there some way to get bedding mass or some other goo in between the bases and the receiver? If I'd mount a scope on there while it sets, wouldn't that ensure that the bases are mounted well relative to each other?
I assume that the scope is straighter than the receiver, because the straightness of the scope is likely ensured by a tighter tolerance than the surfaces on the receiver, which was designed long before this kind of bases was a thing.
The two scope bases are mounted on a surface that as far as I know was never intended to be used as a platform for mounting optics. What are the tolerances as far as parallelity of the forward and rear reveiver rings? There is nothing ensuring the alignment of the bases as they are screwed to the receiver, except a minute cone shape on the bottom of the screw heads. In most other applications one would have added guide pins (two per base) to ensure that the bases go on straight relative to each other.
In our days of mil/mil scopes, full length top rails and very accurate factory rifles, we take scope mounting for granted.
How do I put the bases back on the rifle the best way? I know a lot of people recommend just screwing them on there and then grinding the scope rings with a kit. It seems backwards to me to correct the scope rings, that most likely, since they were actually designed to hold a scope of a specified diameter, have tighter tolerances than the surfaces on the receiver.
Is there some way to get bedding mass or some other goo in between the bases and the receiver? If I'd mount a scope on there while it sets, wouldn't that ensure that the bases are mounted well relative to each other?
I assume that the scope is straighter than the receiver, because the straightness of the scope is likely ensured by a tighter tolerance than the surfaces on the receiver, which was designed long before this kind of bases was a thing.