Lyman 43rd Edition: Bullseye: 3.0 - 3.5 gns for 869 - 961'/sec from a 4" bbl; Red Dot: 3.0 - 3.6 gns for 858 - 963'/sec; Unique: 3.5 - 4.5 gns for 883 - 1039'/sec; Herco: 3.6 - 4.6 gns for 840 - 1010'/sec.
I prefer the Unique powder as providing the widest range. 4 gns of Unique will move that slug to almost 1,000'/sec, which should take the bowlingpin off the table if you hit it square - roundnose slugs have a tendency to 'glance off' bowling pins - it may rock them but unless you hit them square they will remain standing.
You can also try the old Lyman358480 133 gn cast swc for the 38 Super or resize a 141 or 148 gn wadcutter to .356 and seat it as far out of the cartridge as it will go and still chamber in your pistol - bowling pins do not like wadcutters.............