To answer the original question, .45 acp target loads (also called softball loads) are down loaded shells that are specifically used and required for certain indoor target matches, at distances of 50 feet or so. They are made to be accurate, and just powerful enough to operate the slide of a 1911 auto.
The most popular brand of these is Federal Gold Match, which come in both 230 grain bullet loads and I think 185 grain loads. They are expensive, about $35 a box or more. You can get them through most big companies, such as Midway and sometimes Cabellas.
I do not reload and can't give advice on that subject, but I believe that the factory specs for these softballs is about 750 feet per second, as opposed to 850 feet per second. Still a hard hitting round for a handgun.
For me, I just don't see the appeal of shooting this ammo with a conversion cylinder out of an Italian remake of a blackpowder cap and ball. It looks like the cylinder has to be removed for each reload, and then unscrewed to open it up for new shells, and then put back into the revolver. What a slow boring process, and for what?
Best Mannyrock