Originally Posted by
KhanRad
Not Doc, but it is a electro-plating process. Soft lead bullets are submerged in a copper solution, and the copper molecules attach themselves to the lead molecules on the bullet's outer surface. The weak point of the process is that it needs softer lead bullets for the copper molecules to attach to, and the copper coating is pure copper which isn't very hard. The result is an overall soft bullet. Gold Dots use this process, although they have a copper partition in the middle to add strength and when the bullet expands you can see the copper "dot" in the center(hence "gold dots").
Bonded bullets are MUCH more durable since they use a harder lead alloy for the bullet, and a harder copper alloy for the jacket, which is then fused together using the same electro-chemical process as plated bullets. The jacket does not adhere to the core as well as a Gold Dot, but the overall structure of the bullet is better.
HSTs use a deep bullet cannilure which serves two functions. It helps prevent core/jacket separation, and it helps prevent the bullet from over expanding. Remington tried to copy this with their Black Belt ammo.
Personally I still feel the HST is the best overall bullet design for the major calibers. It is about as durable as many bonded bullet designs, it has great penetration/expansion characteristics, and it is relatively affordable. We started using Speer G2s for a few years, and have gone back to the HST.