Jackie, scope Question

B

Bob Kingsbury

New member
My curiosity about scopes has gotten the best of me. Not wanting to tear into an assumed good scope, I disasembled a BSA, just for
starters. The crosshairs were actually loose. More important.
a small sleeve threaded on the forward end of the erector tube was
about 4 turns from being tight. That is where the adjustments contact
in this model. Adjustment marks there show that that small sleeve had not unscrewed, but was apparently never tight. A very loose fit at best.
Given adjustment turrets spaced 3 1/2 to 4 inches away from
The pivit point on the erector tube is scary enough. If we had sand
bags spaced that close, we would never hit the bull in the A---.
So, more to the point. Where is the gimble joint in a weaver and
1'' leopold. and is it actually neccessary to remove the front lens
or can it be done from the eyepiece end alone. Can the gimble joint itself be frozen
 
Bob

Let me first say that The Weaver, Sightron, B&L, and BSA all share the same design erector tube mount, that being a gimble ball mounted in a sleeve assembly. I call this "the universal Japaneese design". There are a few varations in how they secure the assembly inside the scope, but for all general purposes, there isn't much difference in any of them.
The 36x Leupold is different. It has a small sphericle shoulder machined into the scope tube, and the erector tube has a stepped up diameter at the eye piece end that seats against this sphericle shoulder. It is held in place by a wave spring that is pre-loaded by the reticle nut. That forms the pivot. The other end is simply springs that keep the forward end of the erector tube against the adjustment knob abutments.
On the leupold, you actually do freeze the pivot joint. I machine a ring that fits around the objective end of the erector tube, this centers the erector tube. I JB Weld the ring to the erector tube, then JB Weld the ring and tube inside the scope body. I place some JB Weld around that shoulder on the erector tube and on that shoulder machined in the scope tube, and assemble the whole thing, reticle and all. When the JB sets, the erector tube is permanently frozen in the scope.
You have to remove the front objective, (it just screws off), because you have to insert that ring in the scope body from the objective end and then slide the erector tube in from the eyepiece end. It will bottom against the shoulder that machined inside the scopes body. It of course slides into the ring that is JB'd inthe objective end.
On Weavers, (and other Japanese designs), you have to remove everything from the erector tube, and then machine rings to fit each end of the erector tube so you can mount the rings. I glue the rings to the tube, (after some minor machine work on the tube), let it set, then glue the ring-erector tube assembly inside the scope body. You have to pay particular attention to the forward and aft placement, as this is what determines the focus. The Leupold has that fixed shoulder that the erector tube seats against, so it is no problem.
If yo do miss the forward and aft placement a little in the Weaver, you can adjust it with the spanner nut that is inside the objective bell.
Hope this helps.......jackie
 
Thanks Jackie, that will be very helpful. Its painfully clear that with
the possible exception of a few good scopes, we will not get
the performance and life from standard designs.Knowing that a scope
has not failed would be a great relief
 
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