You're headed for some frustrating & fun times [img]/ubbthreads/images/graemlins/grin.gif[/img]
Some suggestions on your first question:
First you have enough rifle now as far as caliber goes.
Next you may wish to consider a bit heavier bullet. One with a better BC. These usually won't be the partition bullet.
It'll thump me too much you say? Nah, not with a good muzzle brake
, which is another consideration.
If possible move your target for load development out to at least 200 yds. 300 would be better. Added feature is the exercise gained.......
Having said the abouve: I'd start with the rifle you have.
First a good cleaning. Remove all copper and all carbon from chamber to muzzle.
Then I'd get 'er pillar and skim bedded and fully free float the barrel.
Then I'd start load development again.
If the barrel was properly broken in and still doesn't shoot well after all of the above I'd consider the Tubbs Final Finish processas a final step. Don't think one can go wrong with it any time in barrel life of a factory barrel.
Geez, I hope you haven't already thought of all of these things. I feel like a dope, again. [img]/ubbthreads/images/graemlins/crazy.gif[/img]