27 August 2018
I have good success with BPI Original filler in my .500 S&W rifle load for Bear. I chose to use the filler because my bullet is plain based and the filler provides a quasi gas check to protect the bullet base. This is per info and recommendations from BPI. My load:
RCBS 50-340-SWC as cast .502" in #2 alloy, Tumble lubed twice 45:45:10.
30.2 gr H LilGun
BPI filler, 11.8 gr to rim
1700 fps verified.
Note that the same load but with 35.3 gr WC820 clocks the same velocity interchangeably.
BPI is a fluffy flake high temp plastic filler that compresses easily and measures well from a Lyman #55 measure.
I get zero leading in my single shot Handi .500 S&W Mag. and attribute that to bullet fit as any cast bullet smaller than .502" in that rifle leads like bad, filler or not.
I practice and hunt with a Triggerstick monopod standing and kneeling, and the both loads consistently group <1" @ 50 yards.