It is easier to get close to the lands with hunting bullets than target bullets as hunting bullets have a longer full diameter length.
It's been more than a decade since I had the rifle. From memory, I tried the Hornady 58 grain Vmax, Speer 70 grain TNT, Hornady 75 grain HP, Speer 80 grain SP, Sierra 85 grain HPBT, Hornady 87 grain SP (looked like a round nose), Nosler 95 grain Partition, and Sierra 100 grain SPBT. None would touch. The Hornady 105 Amax was discontinued and if I remember correctly it needed a 1-9" twist to stabilize, so it wasn't like the super long target bullets we see today.
Did you have a 721 or 722? I was thinking these rifles probably got shot more than most of the newer rifles today. It seems many people nowadays sight-in a rifle and never use it again or use is sparingly. It makes me think of my uncle who has a 244 Remington in a 722 which has been shot alot. He doesn't have that many rifles. His son is the exact opposite and has many and doesn't shoot any of them very much.