I've been shooting my M70 375 H&H with a Leupold 1-4X scope in Talley bases and QR rings. My go to load is the 300 grain TSX sighted in 2" high at 100 yards.

Today I took the 1-4X scope off and took the rings and mounted them on a Leupold 2.5-8X and installed it back in the bases on my M70.

The gun shot 8 inches lower at 25 yards with the same load that was 2" high at 100 yards with the old scope. I ran out of adjustment at -2" so I then shot it at 100 yards and found it shooting a .5" group dead on the bull with no vertical adjustment left in the scope.

Any ideas?

About 15 years ago, I had the same problem with an old Vari X-II. The older ones did not have as much ajdustment as the later ones. I got a shim for the front mount and that fixed it.

quote:

Originally posted by armadillo:
About 15 years ago, I had the same problem with an old Vari X-II. The older ones did not have as much ajdustment as the later ones. I got a shim for the front mount and that fixed it.

The 1-4x is an old VXII and has a lot of up adjustment left. The 2.5-8x is a VXIII and is topped out.

I don,t know but I hope this thread carries on and brings some understanding to some of my scope woos ..
I have a 2-7 VX II that gave me some troubles on one rifle , wouldn,t adjust far enough . Put it on another rifle and it works well ...Obviously a ring or mount problem ..

I have had different but similar sighting in problems in the past...

I,m glad it is wackin them in nice little groups @ 100 tho .. Is it still 8 low @ 25 ??

Armadillo
Were you shooting low as well before you shimmed you Front ring? To raise the point of impact you have to shim the rear ring to bring up the point of impact. Just trying to clarify for my own curiosity. I also noticed that the older model Leupold variable scopes had less vertical adjustment. I had a problem with one on my Browning Safari 458 Win. Mag. I used a lapping bar and found the rear ring actually a bit lower that the front ring. The shim cured the problem.
Thanks and good shooting.
Bob G.

If you got the time and patience, you could send it back and have the factory look at it. They would re-calibrate it and refill it with nitrogen and center the adjustments.
Have you looked backwards through the scope and checked the attachment points of the cross hairs?

quote:

Originally posted by Pegleg:
If you got the time and patience, you could send it back and have the factory look at it. They would re-calibrate it and refill it with nitrogen and center the adjustments.
Have you looked backwards through the scope and checked the attachment points of the cross hairs?

I've never heard of looking back through the scope, how does that work?

I think that everything inside the scope is attached well as I was shooting cloverleaf groups over and over again with it, I just have no vertical adjustment left.

Checking my book, with the scope adjusted all the way up my 300 TSX load was hitting dead on at 100 yards and 25 yards.

The 300 grain Hornady Solids with 64 grains of IMR4064 were hitting 3" high at 100 yards with the same scope setting. As I increased the powder charge the groups slowly moved down and slightly left. At 67 grains of powder the Hornady groups were 1.5" high and 2" left of my TSX load.

I did put a .020" shim under the rear ring and that moved my groups up 2"' at 100 yards.

I left an email message at Talley seeing if they can shave the front mount and get it back to me quickly.

quote:

Originally posted by Bob G:
Armadillo
Were you shooting low as well before you shimmed you Front ring? To raise the point of impact you have to shim the rear ring to bring up the point of impact. Just trying to clarify for my own curiosity. I also noticed that the older model Leupold variable scopes had less vertical adjustment. I had a problem with one on my Browning Safari 458 Win. Mag. I used a lapping bar and found the rear ring actually a bit lower that the front ring. The shim cured the problem.
Thanks and good shooting.
Bob G.

I don't remember which direction it was off, but I know I made it work. I bought shims from Brownells, but I think a piece cut out of an aluminum can would have worked as well. I traded it to someone years ago.

I had a similar problem with a Leupold 2X7 in the early 1970s. My brother had a M700 Remington 6mm Remington that he shot for a while with an old Weaver 6X that I loaned him. When he finally scratched up enough for the Leupold I installed it with a one piece Redfield base and rings. During bore sighting I had to turn the elevation nearly to the stop to bore sight it. He would have had only a few inches of elevation left to sight in with.
It appeared that the rear bridge of the M700 was high. I took the base to a specialty gun shop that had a cutter that matched the M700 bridge profile and had them mow off .024 on the back end. That brought the scope back to the center of the adjustment range. I also checked the rings and they were inline vertically so the scope tube was not bent. I bore sighted it again and took it to the range and it zeroed just like theory said it should. He has used that rifle most hunting seasons since and the scope has never been back off of the rifle.

I have always kept an eye on that issue since then when sighting in. I found a different problem on another M700 that I still own. It is a 25/06 that bore sights near the center of the adjustments but is about 18" low when shot at 100 yards. I think the barrel is crooked but it shoots great so I kept it. One of these days I intend to put some of the Burris Signature eccentric insert rings on it to center the adjustments.

Frank,

Check whether the scope tube is bent. I've seen this very thing on a scope that was optically perfect; fortunately, Nikon replaced the scope for me.

George

quote:

I've never heard of looking back through the scope, how does that work?

Fjold- Just turn the scope and look thru the objective end. You will be able to see the attachment points of the cross hairs surprisingly well. An old trick Russ Haydon showed me.
I've recently had impact problems but with iron sights. Turned out to be the crown on my rifle.
I was surprised how much the crown could effect accuracy.

The first thing you should do with any rifle/scope is set your scope adjustments at the center of the focal plane..Do this by turning your adjustments from start to finish then go back half way...

Now mount your scope and either with a bore sighter or bore sighting on an objects see how for off your center plane you are..

If it is a bunch, you have a problem and the way to fix it is to have your receiver ground or have your scope mounts fitted or both isn't a bad idea...Too many rifles today have the actions ground out of sinc..

A scope should be very close to the center of its adjustments in order to function properly and if your at the outer edge of your adjustments then it will not hold zero well nor will it give you the accuracy that your rifle is capable of...

This can also be done by shimming the bases, but IMHO that is a poor fix..

Any good gunsmith can fix the problem...

Thanks Pegleg, I'll look at it.

Ray, the first thing that I did was set up the scope to the exact middle of the adjustment range. The horizontal adjustment only took 4 clicks to center my regular load group horizontally. The vertical error was huge though.

George,
I'm guessing that you might be correct here. The 1-4X Leupold that I took off worked perfectly so I'm assuming that this 2.5-8 is the issue. I bought this scope used, so I'm going to consider it suspect.

I'm going to take it off and put a 3-9X Leupold on the rifle and see if that fixes the issue.

It's a good thing that I keep extra scopes on hand.

Fjold- Send the 2.5 back and ask them to look at it and upgrade it with any free factory upgrades they could offer. Leupold is a great customer service oriented company.