jhalcot - you might be right in that this lightweight slug may be a good paper puncher but you will have to try it out. I checked my older Lyman manuals and the lightest weight cast slug I found was a 175 gn swc with 2 grooves.
My Lyman manual shows an accuracy load of 5 gns of Unique under the 185 gn slug for about 670'/sec. I think that 161 gn slug may perform best at slower velocities. I would try some at that loading to see how your 45 shoots.
I know that Cor-Bon has a 165 gn jacketed 45 slug that is supposed to move at some ungodly supersonic, hyper-warp velocity but those I have tried wouldn't group worth a darn from my 45s, so I still have half a 10 yr old box of that stuff hanging around.
Good luck, and let us know how they shoot. HTH. Mikey.