SigPros, I just finished working up practice loads for my Sig-Pro and approached it the same way I do for my rifle rounds....I like to use a variety of bullets as well...115, 124, and 147gr in different configurations...124s seem to be the most consistently accurate with a variety of powder charges...My Sig likes 5.1gr of Ramshot Silhouette...clean and accurate..
Get the published max load for the round and drop down one full grain (as long as it doesn't go below published min load) and then build a series of ten for each charge weight, seating the bullets at magazine length...I'll shoot five at 25 yards at small targets and pick the best group and go with it...I just use a padded rest (rolled up shirt on an ammo box) for my shooting hold under my wrists..with a two hand hold for stability...
After I find the load I like, I set up my progressive loader with those specs and crank away...
The power split for major/minor calibers in IDPA used to be 165 (165 gr bullet at 1,000 fps), but that may have changed in the last few years...
I know that it was originally set up for the .45 acp shooting a 230gr bullet at 800fps would qualify...I kept insisting that my 10mms would over ride those but Bill Wilson was a advocate of the .45acp and didn't want to listen...
He's so stubborn about the 10mm that even though he has the capability to turn out great magazines, he won't offer 10mm mags for 1911 frames...I have to find those for a Delta Elite...fortunately I have ten of them...