I have used Tightgroup almost exclusively for pistol reloading for the past several years in .38 Special, 9mm, .45 ACP, 44/40 and .45 Colt with both lead and plated bullets.
It is accurate but only useful at “target” velocities.
As an IPSC shooter I have always had to overload from .2 - .5 gn to make power factor in both 9mm (125 PF + margin) and .45 ACP (170 PF + margin). My loads are often noted as being on the hot side by my fellow competitors. Recently using my long standard published max plus load of TG in new .45 ACP Winchester cases I had a number of cases blow out on me. I have since changed to .W321 for both 9mm and .45 ACP. I still have to load slightly higher than recognised max published data to make PF but by much less a percentage and at lower overall pressures (15,500 instead of 17,000 PSI in .45 ACP according to Quickload).
As my .38 Spec, 44/40 and .45 Colt loads are much more on the mild side I will keep using TG in those calibers.