It is my understanding that, not too long ago, all the heavier caliber Balistic Tips plus the 180gn 308 were 'toughened.' The jacket is now made thicker toward the base. Have I got this right? I now notice that Nosler is making a 168gn 308BT. Is this heavier, toward the base, also? If so, will the 165 still be avaliable? Thanks for your help. capt david