The six inch drop from 200 - 300 yards is perfect but the 3 inch rise from 100-200 is just weird. A 100 yard zero should mean -2.5 at 200 and -8.5 at 300. Is there a booger stuck between your rear base and the top of your rifle? With that said, as long as its consistent... you have a really good thing going.
There are really two options for a 7mm RM... 1...as mentioned a couple of times, sight your rifle in for maximum point blank (which is something like 336ish yards)...that puts you 4" high around 158 yards out and 4" low at 336 yards (zero at 284 yards)...anywhere within that range you center the shoulder with the crosshair and squeeze the trigger... see http://www.backcountrychronicles.com/maximum-point-blank-range/ for additional options--4" above/below = 8" target... 2...you mentioned that you had a Nikon scope...does it have a BDC reticle...if it does, follow the directions for it...that means you will need to set your main crosshair to zero at 200 yards then verify the other marks at their suggested range...with this system you are good to aim and shoot out to 250 yards...but can fine tune your placement if you know the range to target (so a good rangefinder is a big help)... 3...basically the same as 2 above, some rifle scopes have turrets that can be adjusted in the field to specific distances...if you have a scope with adjustable turrets follow the directions on how to set up...those may require a 100 yard zero and you adjust from there...the advantage with this system is that your range with a 7mm RM is only a function of a good rangefinder and common sense...Savage rifles in 7mm RM are generally far more capable of reaching out there than all but a handful of shooters... 200 yard zero with 140 grain Federal Nosler Partition 50 yards = 0.4" 100 yards = 1.3" 150 yards = 1.2" 200 yards = 0 250 yards = -2.4" 300 yards = -6.0"
first kill with my 7 mag last night, Highly impressed 150 yd. doe shot, she never flinched, shoulder shot. 150 grain core lokt. Gun was sighted in two inches high at 100, and I hit about that high on her where I had the crosshairs.