Forgot to add/ask. Are you using a Harris Bipod to site in with?

If so there is your problem. Those things are notorious for causing issues with zero if you do not use them in the field under the same conditions as you use them on the bench.

What ...............Harris Bipods ????

iv'e got many leupolds and once in a while i'll have trouble with them but you will know when your at the range when the bullets are all over the place my last one was a leupold handgun scope mounted on my 454 casull just blew up the internals but leupold fixed for free of course.

You changed your resting spot on the fore arm, different fore arm pressure.

Have you checked it right after a poor shot on a deer. May just be as has already been mentioned target panick.

Definitely resting the gun/barrel in a bad spot! Years ago, I had one of the "dream mornings!" I shot at 3 different bucks and missed! I didn't have the heart to even pull the trigger on the fourth one, and just watched him walk. After analyzing everything from my gun to my sanity, I realized that I was resting the "barrel" on a rigid rest, altogether different than range shooting! Since then, I've been dead-on accurate! Not the gun, not the scope, not the bullet, and really, not the shooter,,,,,,except where the shooter was resting his rifle!

Exactly what I told the OP in my post #5 that can cause big problems with accuracy!