Another scope mounting question...

Pro-Line · 08-10-2004, 08:40 PM

I have a cheap old Marlin 60. It shoots great, but the scope mount must be crooked. I have put 2 different scopes on top of that thing, and the zero changes according to yardage. If I put it dead on at 25yds, it is off at 15 and 35. I mean off over an inch. The last scope I tried...a Tasco Pronghorn that I took off a muzzleloader package....was on at 25, low and left closer, high and right further away.

Everything is tight, too.

I've had this problem with scopes before, but only windage or elevation, not both.

What's the best way to remedy this? Could my rings be the problem?

sot_II · 08-10-2004, 08:57 PM

There are a couple issues.
[ul][*] Trajectory, depending on the bullet, barrel length and a bunch of other internal and external issues , you'll be off at certain distances.[*] You may be mounting your scope with a cant (a slight rotation left or right of the scope body within the mount) It may look good to you when you shoulder the gun but may not be "level" with respect to the true horizon. There are tools that can help you align the scope "level" in the mounts. V-blocking, gride true alignment somethings you can google and find out more about.[*] You may be shooting with cant yourself. You don't say how you are testing this or what the shooting conditions are so I would need more info to help you there. Remember outside, wind is a factor even at "short" distances.
[/ul]

Pro-Line · 08-10-2004, 09:33 PM

Wind will not push a 22 bullet 2" in the time it travels from 15-35 yards...every time. Even with different types of ammo.

I was shooting off a bench. The crosshairs were leveled the same as the 100 other scopes I've mounted. I put them in my gun vise and line it up with the mortar joints on the wall. Maybe the grooves on top of the Marlin are warped or crooked.

I asked my gunsmith buddy, and he said that the 60's were usually pretty scope friendly.

sot_II · 08-11-2004, 07:12 AM

Then you seem to have a cant problem in the scope, gun, or mounts.
I'd swap the mounts around all different ways, try a different scope and mount combo if possible. If you think it's the dovetail, you can mic it with calipers to see if they are true.
One other thing, try placing the mounts further or closer together...maybe there is a small bulge or lack of true in the dovetail.