Two diameter GG bullets

[flatsguide]

Well thanks guys. That will get me going in the right direction, although Kurt's suggestion of going to a PP bullet has crossed my mind. It seems like the chamber of the Browning might favor a PPB wrapped to or .001 over bore dia. One could then seat the bullet well out into the lands and gain powder space, as opposed to a GG bullet that one would have to seat deeper into the case.
But that last statement begs the question why can't a GG bullet that casts bore diameter, .450, be seated out into the lands just like the PP'd ones?
I mention powder space because It seems to come up so often, particularly when it come to .45-70 for the longer, 600 + yard! shooting. I guess I should add here that I plan on shooting Silhouette, but did enjoy long range shooting years ago. My line of thought, that may be in error, is that a good load that would work for Rams may not work for 1000 yard target work, but a good load for 1000 yard work would be good for Rams, so why not develop a long range load that will work for both.
Just trying to get a handle on which direction to go and in the meantime I'm building a PID temp regulator.
I do appreciate your insights guys.
Regards, Richard