I'm doing load development in 06 at the moment with Horn 165 SP (bullet # 3040 - flat base). I'm using H4350 and Re17, WLR primers, seated 0.020" off. My rifle likes Re17 under Horn 150's and 180's. To my surprise, the H4350 grouped better in my gun with the 165's. I'm re-shooting 58.0 H4350 and 56.5 Re17 this weekend. I suspect the H4350 is going to go deer hunting this fall.

As others have said, I've had better luck with bullets other than Speer. In order, Sierra, Nos BT, Horn, Nos PT, Speer. There are exceptions - my 35 Rem Contender loves both the 180 and 220 FP. When I'm having issues with groups, I usually load some tried/true loads with Sierra or Nos BT and try that. Usually, the gun will shoot the Sierras/Nos BT into small groups - that tells me my gun may not prefer bullet X I'm trying to force feed it. In the case of Nos PT, I usually accept a bit larger group size as a trade off for bullet integrity. I'm pretty sure a 1.25" gun will still kill elk just as dead as a 0.75" gun at the ranges I shoot.

As a reference, my current 06 shoots bullets into 1 - 1.25" groups. I consider this pretty good for a OEM stocked, no stock enhancement, pencil barrel Ruger Hawkeye (Ruger UL with 20" barrel). The gun wasn't designed to be a 500 yard bench gun - it was designed to be carried. I carry it alot and use it for treestand hunting. 99% of my shots will be less than 200 yards, most less than 100. It plain works well.

Adversity doesn't build character, it reveals it.