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dbuffington
February 26, 2012, 04:08 PM
Hi Folks!

I have an older Leupold scope (fixed 12x with adjustable objective) now mounted on a Browning B78 (a.k.a., Winchester 1885) using Leupold STD bases and mounts.

http://www.buffingtonassociates.com/davephotos/B78mount2.jpg

However, at with the maximum adjustment of the dials, the the point of impact at 100 yards is still about 4 inches high and 4 inches left of the point of aim.

http://www.buffingtonassociates.com/davephotos/B78test.jpeg

I understand I can make a rough windage adjustment using the centering screws on the base. (But which way should I move the scope?)

That leaves the elevation problem ... that is, what can I do to bring the point of impact down?

Thanks!
Dave

musher
February 26, 2012, 04:23 PM
Ya, handle windage as you say.

First check the scope on a different gun with different mounts Might not be the mount at all...

If the scope is ok, maybe you can handle the elevation problem by

1. shimming the rear base upward
2. mill the underside of the front base lower with a ball end mill
3. measure your rings and make sure you haven't inadvertantly ended up with some combination of low and medium (back and front) that's screwing up your elevation
4. maybe some combination of medium and low (back and front) or whatever will get you on with your adjustments in the center or bottom half of the scope adjustment range.

You might have to to lap the rings to get a decent fit.

dbuffington
February 27, 2012, 11:17 AM
1. shimming the rear base upward...

Which wouldn't be difficult with a thin piece of brass. Thanks!

Scorch
February 27, 2012, 06:38 PM
Shimming the rear base upwards will raise the point of impact. You are already hitting too high. If you are going to shim anything, shim the front.

To move the POI side to side, move the rear in the direction you want the bullet to move, in your case to the right.

Is that the original barrel? The profile looks like an aftermarket barrel.

dbuffington
February 27, 2012, 07:31 PM
Shimming the rear base upwards will raise the point of impact. You are already hitting too high. If you are going to shim anything, shim the front.

Aaack. I taught myself Calculus, and still, this sight movement stuff makes my head hurt :p

Seriously, I now have another reason to suspect the front sight ... I've seen some other photos of B78s, and the front base is turned the other direction. Hmmm.

Is that the original barrel? The profile looks like an aftermarket barrel.

It is indeed original.

Thanks!
Dave

Clifford L. Hughes
February 27, 2012, 08:22 PM
Buffington: I'm not going to adress your elevation problem because many members already have. The windage is another ball game. First you must center the cross hairs in your scope. You do this by running the cross hair knob all the way to one side then count the number of clicks that it takes to move the cross hairs to the other side of the scop. Now divide the number of clicks in half and bring the reticle back this number of clicks. Now adjust your base windage screws untill, through your bore sight, the cross hairs are centered.

You might try a new base and rings for your elevation problem.

I have the same scope; however I have target turrets an a small dot reticle on mine. It is a deadly combination on ground squirrels.

Semper Fi.

Gunnery sergeant
Cjifford L. Hughes
USMC Retired

dbuffington
February 29, 2012, 07:58 AM
Many thanks! Did you have the target turrets installed by Leupold?
Dave

P.S. I also received a detailed response to the same question from Leupold...

If the scope was mounted on another rifle prior to being mounted on the Win. 1885, you should re-center the scopes adjustments. It could be that you have a lot of adjustment dialed into the scope as a result of being mounted on the other rifle.

The elevation and windage adjustments of a scope can easily be centered. Place the front of the scope against a mirror or place a small mirror against the objective end of the scope. That would be the end farthest from your eye as you look through the scope. Make certain that the mirror is large enough to cover the entire objective. It must also be flat against the objective. Look through the eyepiece as you would while aiming at a target. If the scope's windage and elevation adjustments are off center, you will see two images of the reticle (cross-hair). To reach the center of the adjustment range, simply turn the elevation and windage dials until you see only one image of the reticle in the center of the scope.

Now when sighting in the rifle, use the large slotted screws (windgae screws) at the back of the mount to make all your coarse windage(left & right) adjustment. Just fine tune the left or right with the scopes adjustments.
When using the windage screws at the back of the mount, you will loosen one screw and tighten the other. Basically you are moveing the back end of scope in direction you want your point of impact to change down range.

The reason for making all the coarse windage adjustment with the screws at the back of the mount instead of the scope is because....the more windage you dial into the scope itself, the less up and down adjustment you will be able to utilize.

If after following this proceedure you find that you still don't have enough elevation adjustment, you may need to place a shim between the base and receiver at the rear.