Do you load your own or only shoot the factory loads?
If loading your own, you might try using RL-22 or H-4350 with the 165gr loads. If you need something more than a standard bullet, use the Nosler Accubond or Hornady Interbond. Both can be had in 150gr and 165gr weights, as well as Hornady's standard Interlock's. Most of these can all be had in the 180 gr weights as well but for your rifle I would stick with using a standard bullet over the newer types simply doe to the velocity you will be driving them to. When you get starting velocities of around 2800 the impact velocities sometimes do not promote good expansion from the heavier bonded core bullets as well. There is also the Remington Core Lokts as well to choose from.
If shooting only factory you might give the Hornady 165gr Interbond in either the standard or Light Magnum load a try, as well as the Remington 165gr Core Lokts. I know they aren't the newfangled stuff but they do have a long repetition for working.
I have three 03A3's with the same barrels of which only one has shot factory ammo since I owned it. IT shot the Remington 165 load great keeping them under 2" at 100yds easily in a pretty stiff wind. Both of the others have done exceptionally well with the powders listed above and Win cases and primers. They will both shoot 1" at 100yds and most times if I do my part will generally get somewhat smaller in good conditions. One thing I onted with them all is a very good or extensive cleaning did wonders for them initially. Not knowing the history behind yours, you might give it a really good scrubbing with some Montana Extreme or Sweets, just to be sure you got the crud removed. Then a good coat of oil on a couple of patches and your in business. After this was done on mine they now shoot just about any weight I choose reliably. I however have no need for anything heavier than the 165's.
Wish you the best on your hunt and hope you find a load which works in yours.
