There's more that goes into hp's than meets the eye. This is an over simplification on alloy and hp size/shape.

Typically you want to use 1bhn alloy per 100fps up to 12bhn. meaning
8bhn ='s 800fps
9bhn ='s 900fps
10bhn ='s 1000fps

The shape and depth of the hp play huge roles in how the hp performs. Same bullet with 3 different hp's as cast.

Penta point ='s 800fps to 1000fps
Large round hp ='s 1000fps to 1200fps
Small round hp ='s 1200fps to 1400fps

In the 5-24 post above, that bullet was done with a center drill. Center drills make an excellent cupped hp.
4-piece Center Drill Set

The 158gr bullets pictured below do well in the 38spl's and heavy 9mm's with their large hp's.


Swaging jacketed hp's from range brass:
It depends on what you want to use the hp for when it comes to weight retention. It took several tries to come up with a hp for hunting with the 44mag that would expand and stay intact. Simulating the velocity of the hunting load for +/- 75yd hits.

The 45acp on the other hand, I wanted the bullets to frag/implode. These bullets left fist sized holes in wet pack and were 7 1/2" deep or out the back of the 9" bundle.


Ness bullets for the 30cal's. The ness bullet was designed for pest control in gardens without having ricochets.The hp is extremely large/long. A cut-a-way of the bullets hp.


That ness bullet in wet pack 13bhn/1800fps. All that was left was the gc/base of the bullet. The rest vaporized.


A hp whole is 1 thing. Making the wright hp hole for the bullets velocity and the type of alloy being used is another.