ajj wrote:Evelio: I'm surprised at your report of scopes topping out. My three Weaver T-24's have WAY more than enough elevation adjustment to go the 8 or 10 MOA from chickens to rams. I must also report that I know a guy who bent not one but two scope tubes trying to shim. I've never shimmed a scope and don't know what he did (wrong) but it seems to be a hazard at least.
Not arguing. I'm a lawyer and I refuse to argue during my recreation time. I guess I'm just asking whether you've had problems with the Weaver and advising people to know what they're doing before trying shimming.

ajj,

I agree that you may not need to shim the Weaver T scope for it to work. Is it in the center of its adjustment were it is more reliable that

As usual, I'm confused - dyslexia sucks. Evelio has a good point, that keeping the scope near the middle of the adjustment range is a good thing, but wouldn't shimming the lower half of the rear ring lower the point of impact? Wouldn't you want to shim the lower half of the front ring? Evelio said it, so I believe it, just don't understand it...

There is an article somewhere on Steelchickens about "Scope Slope". The rear of the scope needs to go up in relation to the front of the scope. You are trying to compensate for the drop of the bullet over the distances being shot. Since the bullet will drop somewhere in the 8-10 MOA range at 110 meters, you need to shim the rear of the scope upwards by roughly half this amount in order to keep the scope as optically centered as possible.

I think that a good starting point is something like 0.004" of shim for every 1 inch of distance between the rings.

SteveM.

I'll have to try this on the rifles I'm setting up for next season.

I have had to shim every scope I have used for sil. I haven't bent or broke any of them.

Paul, that is interesting. My equipment experience is fairly limited.
Yep, raising the rear of the scope requires raising the muzzle to compensate. Ever seen the rigs people set up to try for prairie dog distance records? Rear rings are about five inches tall, front about 1/2 inch, crosshair is pointing at the muzzle of the rifle.

Sophia

Evelio is on the spot. I have set up probably 40-50 rifles in the past 15 years for either SB or HP Silhouette for myself or other

I'm glad my scopes don't read steelchickens.com. I haven't shimmed a scope since the days of the 1903/BSA Platiimun scope. And, somehow, fortunantely for me, my gun/scope combo's shoot well without shimming. I've run Leupold 6.5x20's in the pase bumped to 18X40 by premier reticle in the past and am currently running a Weaver T-24 on all my guns. They all track well, as proved on frequent bench sessions. Maybe I'm missing something.


Kitty.

Is it a matter of running out of elevation, or keeping the reticle in an optical "Sweet Spot"?

The scope I had to shim is a BSA Platinum. It currently is still on the Anschutz and will remain there until after the match this Sunday. After the match, I will put my new Weaver T24 on the rifle.

Here is the question. From the factory the Weaver comes with 60 inches of adjustment. Does that mean 30 up and 30 down or is it dependent upon how the scope is set at the factory?

If the adjustment is split 50/50, with 30 inches available for the drop at 100 meters and only 10 inches required, the Weaver should still be closer to the start of adjustment than the end of the adjustment. Now, I could be way off base here because I know nothing, it is just an asumption based on the adjustment level versus the bullet drop at 100 meters.

As far as the shimming goes, I used 9 inches of adjustment with the shim. I cannot guess how much I needed without the shim. Someone with more knowledge than mine will have to answer that question. Perhaps I can answer it after I mount the Weaver and test the scope without shims.

Hello AJJ
First of all you mention the word that most everybody hates ( LAWYER ).
When I stated the fact, that "most" of the scopes nedded to be shimed, I did not specify any brand in particular.
As Paul, Jettmugg, and Gator stated, they also had to shim the rear ring on their scopes to make sure the reticle is somewhat in the center of the elevation range at the pigs distance.
It actually all depends on how high your rings are, the higher they are , the most shiming you will need.
Now about the new Weavers T-24, they are specially designed for silhouette shooting, so they may have enought range on the adjustment to reach all ranges without shiming.
Now as far as bending or cruching the outside tube of the scope, that still should not have any effect on how the scope tracks. I am not a scope repair man, but I had the miss furtion, (actually I loved it ) to look at some scopes that customers brought to me in pieces, thinking that I could glue them back together, needless to say, you all know what the answer was.
But in the process I had a chance to actually look at the inside of this scopes, and guess what, there is a 1/2'' tube inside, where the crosshairs are mounted, and the elevation, and windage coming right up to this tube is what does all the tracking, the tube is not connected, anywhere to the outer tube, so if you do put a crease on the outer tube, you still will not hurt the functioning of the scope. You actually are not bending the scope.
I don't know how else to explained.
Evelio

So, elevation should be centered (assuming 4 full knob turns from bottomed to topped, bottom it then elevate two turns) and the rear of the scope shimmed until POA and POI intersect on pigs? This would keep everything as near the lens center as possible.

If I'm doing things the way you're talking, I center it at turkeys, not pigs. Turkeys are about the center of the adjustment range needed for silhouette shooting. Of course, I only do that with the Burris Signature rings with the offset inserts or figure out how much elevation adjustment I need and just get mounts with that much built-in. I have shimmed as mentioned above and I have had it make extra deep ring marks in the scope on the edge because the scope was tilted relative to the rings.

That inside tube would be the "erector" tube. It's what the adjustment turrets actually move. Remember when you used to think we were moving one crosshair or the other? Well, I did. Hey, I was young.

Well a friend of mine and I mounted the Weaver T24 on my Anschutz 64 Thursday. Then we sighted it in and low and behold, no shiming required.

Also, the sight picture is so much better. I truly did not know what I was missing until I looked down the Weaver.

Here is a picture of the rifle with the bsa and high scope mounts.