I disagree, I think it's purely old-school thinking that makes people think they need to use 7-rounders for carry. Factory hardball (or any non +P defense loads that are the equivalent of hardball) just isn't all that hot. I shot Wolf factory hardball the last several years in single stack matches all over the place (including two Single Stack Classics). It's fairly mild stuff. My current Single Stack load just chronoed 179 p.f. at the WI Sectional yesterday, making it approximately equivalent to most factory hardball (traditionally a 230 gr. load marketed at 825-850 that actually goes somewhat under 800 fps).
Have you changed anything about your ammo? You gotta watch using plated bullets, some guns don't like them. I briefly owned one pistol (an XD-45 Tactical) that shot anything I fed it except it would choke nearly every round with plated bullets (which are quite soft compared to hard cast or jacketed). I would be very curious to know how your gun functions with something other than those plated bullets.
(By the way, plated bullets work great in my revolvers, I shoot lots of 'em!)
After I purchased a press, this load is the only load I have shot. This is the same load that has been running well in the 7 round mags.