Steve,
Unfortunately, I don't have any experience (or any info) on the 156 PPU bullets.
Must also note that when I started serious hunting elk in the 1970's, it was in Montana over near the border of the Idaho panhandle, which is also thick timber country. Eventually I used the .30-06 with 200-grain Nosler Partitions at about 2600 fps, and never had any trouble with penetration from about any angle. Only one stayed inside an elk, and that was a shot right under the tailbone. Never did find it but the elk died pretty much right there. Those were the old model 200's, the "semi-spitzer" design. Over the years I've found they penetrate just about as well as 250 Partitions from the .338.
