Thanks, Bob. That's exactly the kind of info I needed. I have an early Glock 24 from back when they came with compensated barrels but no "C" suffix for the model number. My plan is trending toward an extended-length .357Sig barrel with multiple compensator cuts both at the slide cut-out and in front of the slide. With sub-90 grain bullets, there should be plenty of gas to help the compensators work.
Any suggestion what powder might be best to start experimenting with? I have some HS6 and AA9 but if there's a "go to" powder for this application, I could use a hint.