Greenhorn to the scene. I am used to shooting a ball 5.56 nato round. this round tumbles very easily. I choked because the deer I was looking at for about 3 minutes was behind several bushes and branches. It was roughly 80m from me, zero wind, light snow and I was prone and my balls froze. I could easily see the kill zones but the brush made me worry about a clean kill. Swamp area is not what I want to drag a 200lbs animal over while crashing thru the ice. Question: how bad does the .06 with a 150gr medium grain round tumble if at all? Next time should I shoot thru the brush? I am an expert shooter by the Marines standards several times over. I am confident in retrospect I should have taken the shot but again, I was worried about draggin the deer, which I could not tell male or female due to the brush, thru knee deep water & making an ethical kill.

I've never seen a 30/06 "tumble" although any bullet will deflect or deform if it hits something, including brush. I won't shoot through brush unless it's literally right up against the animal. You might also want to check regs in your area. In some (like mine) .223s (5.56) are considered too small for big game and not allowed. As I'm sure you know, shot placement is everything and not wanting to wound and chase the animal shows a great ethical decision.

I don't shoot through brush.

Any bullet will be deflected by brush. If the brush is up close to the animal, the bullet will probably hit close to where you are aiming. If the brush is away from the deer, the deflection may be enough to miss. Usually if you have a clear hole through to the vitals, you'll hit it.

I think you made the right decission.
If you don't know, if its a doe, or buck, and brush is there.
You did the right thing, in my opinion.
Like you said dragging a deer in waiste high water, could possably cause highperthermia to you.
So you did the right thing.

JMHO

If you can not totally identify your target it is a no shot, for starts. (Even for me if I have an open buck and doe tag). It does not take much brush at all to deflect a shot. At less than 20 yards a 1/2 sapling deflected a 12 gauge slug totaly off the deer behind it (me shooter, with a friend witnessing) .
A shot not taken is a good shot. You never have to worry about a wounded animal, the animal is still out there and you have a clear conscience. It is cool to let the animal walk- you dont look desperate to kill. It is uncool to make excuses about the poor shot that maybe wounded an animal. It is no big deal to pass a deer, but it is a huge deal to take a shot you will wonder about for maybe years to come. It is the slobs who justify blasting at every flash of brown that ruin the sport, and as time goes on they get even more careless.

Thank you all. Feel a bit better about the choice. Going to the same spot in a few days. Hopefully ill have pix to post on what I passed up.