http://www.longrangehunting.com/forums/f19/berger-thick-bullets-35973/index2.html
The thick jackets were created to solve the failure problem, which they have.
Since we haven't tested them for terminal performance, we can't
know how they might perform, so it would be irresponsible for us to recommend them for hunting, or even say they're OK for hunting.
Since I know some of you guys like to live on the bleeding edge
and you're working on things that the front line answers don't suffice, I'll offer the following additional information.
The thick jackets are thicker by about ~0.005" (more or less depending on caliber)
in the bearing surface area. From the bearing surface to the mouth, the jackets have more taper than the standard (hunting) jackets, so that the thickness at the mouth is nearly the same as it is for the standard jackets.
What does that mean for expansion? One could assume (dangerous) that since the jacket thickness is close to the same at the mouth, that expansion would be initiated the same as it is for the standard jacket, but that the subsequent expansion/fragmentation could be less violent/excessive. Another way to say it is that the bullets might not provide enough expansion/fragmentation on long range, low velocity impacts as the standard jackets because the thicker jackets could hold the bullet together more.
Then again it's possible that the thicker jackets could prevent adequate expansion/fragmentation even at nominal/close range impact speeds. This is the possibility that we're afraid of, and it's why we can't advise them for hunting, which translates to advising against their use for hunting.
Jacket design is a classic trade-off between terminal performance on low velocity impacts vs survivability in high velocity / rough barrel applications. Reliable performance on low velocity impacts drives jacket thickness down, while survivability drives it up. The shooter who wants a bullet that survives 3400+ fps MV from a possibly rough barrel, and have that same bullet expand reliably on a long range shot where the impact velocity is 1800 fps or less is
really asking a lot.
We're doing our best to understand and improve the design of jacketed hunting bullets in order to make the best bullets possible for as wide of a range of applications as possible. I see our current offerings of thick and thin jackets as a stepping stone toward a better solution. One shouldn't have to decide between high velocity survivability and low velocity terminal performance, but that's currently the situation.
Hope this sheds some useful light,
-Bryan