The BPI sabot is tending toward small diameter.
With a .512" slug it measures . 727"---So I run one
into die and reduced it .020". It is lead, swaged easy.
Shot a BPI sabot with 385gr Great plains slug in 700HE
great big gun pictured above. That Great plains slug
was reduced .020". With 300gr of super fast ball
powder blend in 3.85" case got over 4500.

Using slugs with locked on bases and RG's hollowbase
jacketed slug in 3.5" RMC brass cases in the 1887
Win levergun. RG's 670 gr HB- 2500 . Brenekke KO
435gr- 2700, Lightfield 460 gr- 2600 . Even got
a 385gr in BPI sabot to target straight.Levergun has
34" smooth barrel and with chamber for 3.5" long
cases it is run as singleshot. Barrel is a tight smoothbore
going from .726" to .722". Took out lifter and other
stuff and put in a bottom style extractor I built that
is operated by the lever at bottom of opening
stroke. Then take cases out with fingers, thus able to
handle long cases in a short action.Makes a real old timey,
neat looking, single shot blaster.Ed