Last couple years I've been playing and hunting with a couple of 6.5 CMs. Excellant round for long range hunting but I do love my Model 70s.
So its back to my old standbys, M70 Featherweights, 257 Roberts for deer/antelope and 270 Win for elk.
Developed a good load for the 257 110 gr Hornady ELD-X and now for the zero.
My 257 Rbts is a pencil thin barrel post 64/pre FN Model 70, meaning it likes to walk after 7-10 rounds, not good for banging steel at distance but for a hunting rifle, the first shot is the one that counts.
Conditions may or may not be perfect, so for zeroing I like a 10 round group, over a 10 day period. One shot after taking the rifle from the gun safe. Different times of the day, differnent temps and humidity. On the same target, with no corrections until after the 10 days. It may be hot and dry, clouldy, cool and raining. Doesnt matter. I change nothing on the rifle.
I shoot from normal field positions as I would hunting.
If I need to adjust, I'll do it after the 10 days, then start over.
I dont get the best groups, but If I can keep the groups to 2 inches, I'll be happy. That should keep me in the vital zone of deer and antelope past 600 yards, further then I really need for hunting.
My 270 Featherweight is the new FN Model 70, it came bedded and doesnt walk when it gets hot like the 257, still I'll comfirm my zero the same way, 10 shots over 10 days.
This is how I zeroed my Counter/Sniper Rifle when I was in LE. More so then hunting the first shot was more critical.
I have two antelope, a deer and elk tags for final check of my zeros come fall.