My 2 cents worth.
According to the Boys in Lewistown, Idaho, at least back in the early '80's, the Speer 150gr 8mm was their "light" bullet, therefore it was built with a light jacket. I found this out when my 8mm blew up on a Whitetail ribcage and produced a neat little flesh wound, but no entry. Successive shots put the deer down and after I got it home and taken care of, I got on the phone to Speer and that was their explanaton. Never had the problem with a Sierra or Hornady 150gr and 51gr of IMR3031 really lit up the sky when I touched off my Persian Carbine. Bullets lighte than 150gr are available, but never shot well in my rifle.
Regards,
Sweetwater