I am going to be using one of my Stiller predator action as a switch barrel rifle. I was looking on Sinclairs web site at action wrenches and barrel vises. I think i will have my dad make a vise, as he is a tool maker for GE. The action wrench is were i am having some concern. What style is best, the rear entry or port entry. I am sure my father could make one of these as well but i dont have anything except the bolt for a pattern. Would a rear entry wrench work if it were copied loosely from the bolt? What style wrench is the better choice to use? Thanks Lee