If you do shim the barrel, don't use anything that can absorbe moisture, like wood (unless well sealed) or (gasp!) paper (I've seen it before!). A single aluminum or brass sheet of the thickness needed works best. If I have to use multiple sheets of thin material I epoxy the layers together so nothing works loose or slips. The shim gets permanently epoxied to the forearm.
I like Nosler bullets but I've never been able to get the Accubonds or their Competition bullets to shoot for beans and I've tried several (270, 308, 338WM, 300 RUM) in different weights. I've had much better luck wifh the Sierra's. Could be seating depth, I usually go for as long as possible, mag permitting, and have had good luck with most bullets doing this. I'm just in the last 4 or 5 years started trying a few of the all copper bullets, so far some ok, some decent but none extraordinary. My budget is fairly limited so it's a slow process. I simply refuse to hunt big game with anything other than Nosler Partitions. They don't shoot in every rifle and my solution to that is to sell the rifle, which I've done 2 or 3 times! My Win M70 .270 likes the 130 & 150, my Rem 788 .308 likes the 168's and my .338WM likes the 210's & 250's. Even my 336 30-30 likes the 170's, so I pretty much have everything covered.
I also like trying different powders and have lots of different brands & types. I chrono everything and have never had much variation in lots except once with RL15. The new lot produced significantly less pressure/velocity but so far it's been the only one. If I use a lot of a certain type, I try to buy an 8lb. keg, like 4350, 748 and 296. The only variation I've seen in primers has been with custom guns, especially my .22 CHeetah. It prefers the WW over Federals.
They are all individuals and can be picky at times. Sometimes the only solution is to keep trying until you hit the combo it likes. I worked up a load for a buddies 270 but it simply refused to shoot the Partitions, preferring the Speer Trophy bonded 130's instead. They aren't a Partition but it's definitely not a bad bullet, either! Whatever works!
Cheers,
crkckr