I have a Savage Predator Max in .204 Ruger caliber (ser#H387XXX). I would like to change the barrel and caliber to something where I could use a heavier bullet (I do reload). I just don't know enough about bolt heads/shank sizes etc etc. I'm hoping for either a pointer to where I could get the info i need OR, preferably, some answers and advice here. I have no idea how to change bolt heads so I expect that I should stick with a new caliber that uses the current bold head for my .204 (?). So, for starters, what calibers can use my current bolt head? And maybe what specs would I need to know to order a new barrel i.e. shank? YUP, I know what length I want.... Appreciate it....John