I have the 7/8oz mold because my "smooth bore" 870Rem "deer slug" barrel shot the old Browning 7/8oz slug load more accurately than any of the "heavy's". So far, I have loaded it with 17.0 of Red Dot with a AA wad and hull and have gotten about 1350fps. The groups have been about 2 1/2" @ 50yards. I'm going to "shoot for" (pun intended
) for about 1500 to 1550fps, which the loading data indicates is possible with their "listed" powders at normal (shotgun) pressures. The recoil has been relatively low and I have loaded the shotshells on a MEC jr 600 press, just substituting the slug for the "shot", and using a standard "folding crimp". I'll take accuracy over velocity, at this point, if I can find the "magic" slug that will better 2" groups @ 50yards.
According to LEE's data, the 1oz slug can be driven just about as fast as the lighter slug, I've just not owned any shotgun that would shoot them as accurately.