Here is the link to the precursor thread that you have to read for this one to make sense
https://castboolits.gunloads.com/sho...d-cast-bullets
I have cut me some six petal HST style bullets and they are simply too fragile and the flutes come off the body too easily when the bullets blow up.
Checking out several bullet makers, Rocky Mountain Reloading brand 9mm opens up into a three flute lead form when they do expand. They are also noted as "being somewhat reluctant" to fully expand.
Zero Bullets brand 9mm is noted to never expand except in dirt, and are rumored to show a three flute form on the occasions when they do expand in dirt.
Four flute forms are not seen at all in modern 9mm pistol bullets, so I lack a reference for the 9mm four flute form's pistol performance.
You see why I am thinking this ---- 6 flutes are too frail and 3 flutes are too strong.
Anybody got any additional real info on this topic?
Norma has a 4 flute expanding rifle bullet and there may be other older rifle bullets with 4 flutes .....
I looked further and found more examples of older bullets that did skived jacket 4 flute expansion and some that were examples of monolithic copper 4 flute expansion.
(this is a web page with many brands/bullets on it, so please click on it to view it)
https://files.osgnetworks.tv/10/file...llistics_F.jpg
I think 4 flutes would make up a good balanced bullet that would be easy to make up a fixture to produce, so I am going to drive towards simple fixturing for 2 main "all the way across" cuts at 90 degrees to each other resulting in a 4 flute expansion pattern.