PF is always important as a metric, regardless of rules. I think WST/320 is very resilient for sub-major 9, 9 major being a pretty specialized load. Most practical pistol is inside 30 yards. Occasionally we have 40 or 50 yard targets, but they are pretty rare. Loading production ammo down from 130 to 120 PF with 147's, I'd say the big drop is past 50 yards. But at 20 yards it's not a problem at all. And if you keep your production charge constant and go from 147's to 124's, you can drop down to sub-minor and get good hits at 50 yards. Cycling the gun depends on using appropriate springs. If you're going to drop into sub-minor with 147's, malformed bullets may not cycle.