Home Forums Hunting & Shooting Hunting Rifles Scope height - Is my math sound?

Thanks

I try and simplify the math when I do mine. I measure the gap between the receiver and the bottom of the scope. (for an example we will say .25 inches) I know that my scope has a 30 mm tube (which equals 1.181 inches in diameter) and my receiver is 1.35 inches in diameter.
The barrel screws into the receiver at the center line so center of barrel is (1.35/2 = .675") The center of the scope as you stated above is half the diameter so (1.181/2 =.5905 inches
Now I add .5905 + .675 + .25 and my scope CL is 1.5155 inches above my bore.

Same math you did but I just find it easier to measure the gap under the scope tube.

For me, it is harder to find the CL of the barrel at the end of the scope. Most of the time, the barrel is in the radius part of the contour about that point and I can be off on my measurement.

The math looks good to me, but I usually make my measurement at the erector housing since that’s where adjustments are made.

I wish this site had a 👍 option per posts 😁. So in all honesty, for hunting purposes and distances, does it really make that big a difference? I run 0 MOA bases on all my rigs and since this morning I've measured 7 rifles and the difference is any where from .1 to .3 MOA from the standard 1.5" guesstimate.

I called Vortex about a separate question but while I had them in the phone...the guy confirmed my math was sound (long but sound) and anywhere between 100 and 200 yards .1 isn't going to make the big a difference; not that the pig can tell.

Thanks folks

I stack coins shim on the front and rear action where the screw holes are. Then place scope on the shims until there is 1/8" clearance on the scope bell. Meaure the height of your shims and you are then good to go. Look at manufacturers specs to see how their rings are measured and the height.

Center your scope reticle, insert a chamber laser and sighting the scope measure the difference close-up on the wall target.
I always get a kick out out of everyone that automatically wants to keep the height as low as possible, how your normal hold on the rifle is more important.

Phil

X2

This tells height above center of bore how? Methinks you're both confused on what he's trying to determine.

If I read correctly, this is being applied to a big game rifle to be used under 200 yards. How about: 1. Shoot the gun to see where it hits. 2. Practice to maintain your skills. 3. Buy BBQ sauce for the pigs you’ll kill.

No it tells me how well a scope fits on a rifle. Put the scope on the shim bed and you know your objective clearance. I don't need formulas to determine scope clearance. Everyone of my rifles has less then 1/8 clearance on the bell, because my method takes barrel contour into consideration. The OP is confused for sure, what happened to the formula he posted?.

Says the person that uses a chamber laser.

That's great and all, but that's not what he was asking. He was wondering about figuring height of his scope above the bore. You see, that's one of the numbers you plug into a ballistics program for getting trajectory data.

Get the measurement from the center of the bore to the top of the receiver, add the shim measurement and half of the scope tube diameter and there is your answer.

If you already have the scope on then height of receiver to middle of scope tube and centerline of bore to top of receiver.

👍