No offense PawPaw but missing a deer at 40 yards has nothing to do with your zero.
The 40 yard difference between a 100, 200, 300, even 400 yard zero is small. Much smaller than a deers vital zone.
For instance, a 180gr Hornady SP from a 30-06 with 2700fps MV and a 300 yard zero would be 1.7 inches high at 40 yards. With a 400 yard zero, it would be 3.1 high at 40. 200 yard zero, 1/2 inch high.
Any of those would kill a deer and CERTAINLY not miss it.
The difference between any of the various zeros shouldn't cause any problems. We might make rush shots and misjudge in the field, it's easy to do and I've done it many times myself but we should also KNOW, as in know by putting bullets in paper, where our bullet will be at any range we are willing to fire one at an animal. If you KNOW where your bullet will be, the "problem" is the nut behind the butt, and we've all been there.