Take the dust covers off the rear ring.
Set your windage (back ring) and your elevation (front ring to "zero".
Set up a target at 100 yards to get a your starting zero.
Set the rifle in a good rest (front and rear) and bore sight the barrel and the scope to the target by the use of the screws under the dust caps that you removed.
Do some actual fire at 100 yards and fine tune the zero by use of the screws under the dust caps.
When you have that complete, the scope and rifle will be sighted dead on at 100 yards and the Windage and elevation will be set at zero. Now make your elevation and windage corrections when going past 100 yards. When your done shooting, rotate the rings back to zero and your always on a 100 yard zero to start the next time.
They are 1/4 clicks and the cross hair is etched on the glass. A great scope for longrange hunting. They were way ahead of their time.
I have a Kuharsky rear base on mine that looks like a large Unertl rear base. It gives me over 450 1/4 min clicks. I have not found a better scope for longrange hunting then the 6X to 24X Balvar (old style) and I've used most all of the curret scopes.
You will not be able to get out past about 650 to 700 yards with the factory rear base unless you start out with a 300 or 500 yard zero by use of the screws under the dust caps.
Yes I love the scope, and it looks awesome on my 1967 Remington heavy barrel 6mm. Shot a .500 3 shot group at 100 yards, with factory ammo. I hope to tighten this up with a good handload. Then set scope for 200 yards. And record clicks for ranges to 500.
I have a place to shoot groundhogs out to 1000 yards, on a large dairy farm. Planning on using the 6.5 Gibbs beyond 500 yards.
Sure these sound like short shots to some of you seasoned guys, but I am excited about some long range hunting.
Grateful, to all for the help. Us rookies require extra.... LOL