You will either have to shim the rear base or change your mounts to Burris Signature rings and mounts. Those have an offset bushing kit available to pick up as much as 40 MOA if needed.

I mounted a scope in low QR rings/mount. At 50yds at the edge of adjustability, the scope is still 3.5" higher than round impact. How do I fix this?

Steve

I'm wondering what scope you are using, I am having the same issue on a 375 H&H model 70. I noticed the scope I'm using, a Leupold 1.75 x 6 has only 35 inches of adjustment vs 64 inches for my 3x9 Conquest that I have on my other 375, I may just switch to another Conquest because I don't want to go with shims.

You may want to check your scope's adjustment range as I looking around there is a large variance between brands and models.

Jim