I am loading the .40-70 SBN with paper patched bullets for an original Rigby single shot stalking rifle chambered in that caliber.
(You need to Login or Register to view media files and links) My rifle has a groove diameter of .411". For these hunting rounds I am patching to
groove diameter. I know that is anathema to most shooters here, but it was British express rifle protocol. It also seems to be correct for this rifle.
My load is:
* 70 gr. of Olde Eynsford 2F, the powder compressed just below the base of the neck;
* a beeswax foundation wad set on the powder;
* a 3/16" thick grease cookie;
* 330 gr. swaged .399" paper patched bullet; I source this bullet from BACO. This is the diameter of the un-patched bullet. With patch it is up to groove diameter.
* WLR primer;
* 2.925" OAL.
Take note of the lack of cardboard or plastic wads. My bullet is seated right on the grease cookie. There's a story as to how I arrived at that practice. The grease is segregated from the powder charge only by the beeswax foundation wad. That's enough, and it lets the flame disburse lube through your barrel. My lube cookie is a homemade recipe that seems to duplicate SPG. A cookie made from SPG should work as well.
This load is accurate and does not foul the barrel. It chronographs at 1521 fps.
By "accurate" I am referring to good hunting accuracy. This load will consistently group at slightly over 2" at 100 yards with the open express sights - no blowing, no wiping, shot after shot.
I can shoot 20+ rounds without accumulation of fouling. The 21st cartridge chambers just as easily as the first. I am confident I could shoot 100 rounds without blowing or wiping, and without any loss of accuracy.
There's a long thread about this rifle on another forum with lots of photos and a long dissertation about how I finally figured out what cartridge it was chambered for. Some people might find that thread interesting. Be sure to read the whole thread, as it spans a number of years. Final load development is way down in it.
(You need to Login or Register to view media files and links) It's worth looking just to see detailed photos of this extremely rare and exquisite rifle.
(You need to Login or Register to view media files and links) I would think a similar loading protocol would make good hunting ammunition for your .40-70 SS.
Curl