Seems to me the older BT's look like the current "varmit" BT's and they thickened the jacket a bit on the "hunting" BT's. Is this correct? Anyone noticed any improved performance on game?

Yes they are different.I've cross sectioned some with a file and the new ones look more like a non bonded Accubond.

I believe when Nosler went to the 50-count boxes of B-Tips was when they had the 4th Generation B-Tip Design. That could be wrong, but I've used the first three Grenerations and they all worked OK when placed properly for each of those specific Designs.

They were all relatively Fragile in the beginning and have changed the Design a lot of times to toughen up the Big Game B-Tips.

I tried them when they first came out in my 270 WIN,was using Hornadays before.They blew large holes in deer even out to 200 yards.
It seems that when they went from the solid bases to the bts,they went to far in the fragile dept.
They have been toughened them now and seem to be back where they once were,but with the plastic tip folks seem to think bullets need to have to work right nowdays.YMMV

I have been using the 150 grain .277 ballistic tips for over 25 years with great success. All on shot stops with massive tissue damage. I have heard of many problems with the lighter 130 grainers but have never heard any complaints with the heavier choices.

If I were pursuing Elk and Moose sized critters I would second guess the caliber as well as the bullet.

Hotcore, I think the 50 count boxes came out with the 3rd generations. The 4th generations started with the introduction of the Accubonds. The accubond uses a redesigned, thicker jacket, and the new hunting BT's are using the same thicker jacket.

Hey AS, you could be correct.

I also beleive the Combined Technology bullets were tougher bullets from their introduction. I use the BT's a lot and find that they have been toughened up a bit too much, losing some of that instant kill ability, at least with the 150 gr. 7MM bullets.