I have never shot a deer with the heavier PBs. But, three years ago when I started BP hunting, I did what very many newcomers to BP do, I started by using PBs and pellet powder. Shot two deer the first year w/ the PBs in 295 grains. To say the performance was bad is an understatement. 2 50 grain pellets was just too much for the PBs at 50 yards or so. Don't get me wrong, it killed the deer deader than a doornail, but the bullets pretty much shattered inside the deer. Both were broadside, both had the bullet fragment and had multiple exit holes. I swore off PBs for anything other than a quick reload and final put down shot (never had to use after I started using Shockwaves).
This year I bought a used Black Diamond for my kids. Because I was using a reduced load for them for recoil purposes, I didn't think that shockwaves would be a good choice. So, I developed a 70 grain 777 load behind a 300 grain XTP hollowpoint. Very nice, accurate, low recoil solid performing load inside 100 yards. My kids killed two deer with it. But, during the second ML season, we ran out of XTPs locally and had to order some. I had some 295 grain PBs left and tested them for POI, figuring inside 100 yards they would be close and we could use them till the XTPs got in. Printed almost exactly the same. I thought with the reduced velocity the PBs would perform better. I was wrong. My youngest son shot a small buck quartering towards us. Bullet went in, hit NO bones promptly broke into at least 3 large pieces, two of which went all the way through. The base of the bullet and enuff lead to weigh about 75 grains ended up under the skin on the other side. Now, the deer didn't take a step, it was dead where it stood. But the bottom line is that had the deer been standing at more of an angle, I think that the bullet would have blown up in the shoulder and maimed the animal rather than kill it.

A fellow that I work with had one of his employees shoot a buck in the shoulder w/ a PB. It blew a big hole in the shoulder and none of the bullet made it into the body cavity. It was like it just exploded on impact. As the deer ran/limped away, another hunter in the club finished it off. Pretty miserable sight from what they tell me.

The heavier bullets may be the ticket, but I personally have seen three deer shot w/ PBs in 295and each time the bullet fragmented. Also have been told of several first hand accounts of similar perfromance. I think the bullet could be fixed if they would just make a serious copper jacket rather than the very thin, I think for looks only, copper "wash/plating".
R
Hank