mike,

as vapodog says, stay away from 2 scopes and rings - more trouble than it's worth.

Re "upward pressure on barrel, I'd get that taken out by a gunsmith. Not good
as POI will change when the barrel heats up.

Just load a few rounds of each bullet weight and go down the range and see where they shoot.
Sight in the gun with your most used load and then try to get the other load shooting to this
point by using different charge weights, bullet seating depth etc etc but ONLY change a ONE thing
at once so you control the variables.

Also, try using ballistic tables to get you as close as can be without multiple visits to the range.

Hope this helps.

500 Nitro