While you projectile slicing is quite good, projectiles are normally sliced right through the middle to give an accurate picture of what is inside and how it is put together. Sanding and or polishing the cut longways as you did is the right way to do it also but with a smother finish.
For the purpose of seeing what was inside, you done OK as those bugger as hard to hold on to when you want to slice them however, you should have notice a variation of hardness's when you drill them.
The brass lining is hard tempered on the tip to resist the temperature and forces exerted while being propelled inside the barrel and them, in trajectory.
Various projectile types are made for the .50cal (as per most other calibres), those seem to be the soft points where the core is either lead or soft metal. These are made not so much for penetration but more for impact (kinetic forces), where the projectile will peal the brass jacket exposing the core and mushrooming on impact.
These would not be the projectiles to penetrate through armed plated stuff, for that, they would be using the full solid rounds with stainless steel or even harder metal as the core, still dressed with the brass to void damaging the barrels' riffling and also sealing the propelling powder gasses properly...!
Anyway, I just thought that you guys wouldn't mind to know a little bit more about these projectiles) or projectiles in general...!
Cheers
George
