shot capsules in .38 Super?

[Mr. 16 gauge]

Been thinking about experimenting with the Speer shot capsules in my .38 Super.....any thoughts re: loads, seating depth, ect? My Super headspaces on the case mouth, so I don't know if that will make a difference. Also, you think that the load that they recommend (5.5 grns Unique) would be a good starting point?

.....Oh, and I know that it "won't cycle the action", and that's O.K.
Thanks in advance.......