For me, any rifle with a long throat where you can not get anywhere close to the lands has been very temperamental to shoot sub 1/2" groups, and the worst was a 270 Weatherby Mark 5.
Individual barrels are usually the fly in the ointment and the chamber design that goes with it.
The most difficult case I have found to tune small groups in multiple rifles is the 22 Hornet, while the easiest is the 6 XC & 6.5x47 Lapua, discounting the 6 PPC and 6 BR as not hunting rifles. As a test, I made brass for the 6 XC from 308 Winchester PMC, Winchester, Lake City '09, and Chinese Military machine gun brass. All the 6 XC formed cases from the 308 brass shot 1/4" groups and smaller, and I consider this a good test of a cartridge design. Also, formed 6.5x47 brass from Remington 22/250 brass when there was no Lapua brass in the country. It took me a few shots to work up a load that shot 1/2" groups at 200 yards with the Remington 22/250 brass formed in a Ruger 77 Mark II with #5 taper, Brux barrel in a Laminated stock in 6.5x47 Lapua, a true Red Neck special deer/hog rifle.