To the OP's original question, here's my limited experience:

Weatherby Vanguard S2 Varmint Special in .22-250, shoots under an inch 5 shot groups at 300 yards with hand loaded 55 grain SGK HPBT, closer to 1.5" 5 shot groups with 40 grain Nosler Varmageddon FPHP

Weatherby Vanguard S2 Synthetic in .308, doesn't shoot the 150 grains Nosler Accubonds all that well, something like 8" groups at 400 yards. Going to try 165 grain Nosler Accubonds this afternoon

My brother and I had identical Browning A Bolt II Synthetic rifles in .270. I got his to shoot under an inch with handloads at 100 yards, couldn't get mine to shoot under 3". I think there's a headspace issue with that rifle, probably need to send it back.

My dad's Remington 700 SPS in .223 shoots 1.20" 5 shoot groups at 300 with hand loaded 55 gr SGK SPBTs.

Just more data points for you