In my experience,shooting national match with an M14, you need 2-3 clicks to go from 100 yards to 200 yards
200 yards to 300yards = 3 clicks
300 yards to 600yards = 12 clicks
That's pretty much the case for M59, M80, M118, M118LR, where you won't find more than 1/4 MOA difference in their trajectories. It also applies to M1 and M2 Ball ammo as well as M72 match ammo in the M1 Garand.
It works for the most part with M852. M852 is loaded slow, at only 2550 fps, and it will be about a half MOA lower at 300 yards, about 1 MOA low at 400 yards and 2 MOA low at 600 yards. However, increase the load to get a 168 gr SMK to 2700 fps and it will match M118 and M118LR within 1/10th of an MOA out to 600 yards.
In essence, what is happening is that the higher velocity of the 149-150 grain rounds offsets their lower BC, and the 150, 168 and 173 and 175 grain rounds have fairly similar trajectories out to 600 yards.
In your specific case, a Hornady 150 gr FMJ-BT at 2750 fps and a 168 gr A-max at 2700 fps will be pretty well matched out to 400 yards with nearly identical trajectories, with the A-max going about 1 MOA flatter at 600 yards.
Whether the zero will be the same is another matter as the recoil impulse and angle of departure also changes a bit with the different loads.
Your best bet is to zero one of them as your primary load, set it up on your rifle with 100 yard basic zero, confirm it at 300 and 400 yards, and then shoot then other load with the same zero and adjust as needed to get a new 100 yard basic zero and corresponding 300 and 400 yard zeros. Then all you have to do is note the change in zero going from your primary load to the secondary, and add that to the scope when you switch from the primary to the secondary load.