Quote Originally Posted by Abasmajor View Post
Hello,

Thanks for the comprehensive explanations from both yourself and others who have kindly contributed to this thread and helped me gain a better understanding of the reasons for using filler in BP revolver loads.

I'm still not convinced about the necessity of seating the ball close to the chamber mouth though because as stated in the original post, the recommended precision target load for nitro revolvers before the 1995 breech loading pistol ban used a 148 grn Wadcutter bullet necessarily seated a long way from entry to the breech necessitating quite a big jump before engaging the barrel rifling.

Brian

Er....when downloading a pistol cartridge such as .38 spl or .357 magnum, the much reduced nitro charge (IIRC 2.7 grains of Bullseye was a popular load) leaves a very large airspace in the cartridge. The bullet is seated to exactly the same place with a reduced charge as with a full load, thus keeping the COL within spec and thus placing the bullet at exactly the same distance from the chamber mouth. Seating a .38 spl to zero airspace with 2.7 grains of Bullseye (even if it were possible, could not be done any seating dies I have seen) would leave the bullet wholly inside the case, and nothing to crimp on.