RE: tight groups
ditto to what these guys had to say. My 700 taught me the hard way that there are many vairables to getting the right load. A couple of things to keep in mind though.
Some barrels are neat freaks, so keep the barrel clean and see if it likes it clean or lightly it fouled. (Mine likes it sqeaky clean with no fouling shot)
Most hunting barrels are sensitive to heat so give it some time to cool between shots.
In my experience nothing affects the loads point of impact(and accuracy) more that bullet seating, so find a oal that it likes and fine tune from there.
If you have a problem rifle(flyers), which it appears that you do not, don be afraid to try a sims doughnut. It worked for me.