Well...
For example, 6.0 gr Unique with 115 gr Berry PRN (2000 AD vintage) at standard factory OAL wouldn't give you pressure signs, but it would foul the barrel pretty badly. I didn't own a chronograph back then. It had the same recoil impulse and POI as expensive self-defense factory ammo, so I felt pretty smart... ...until I found out what Butch's Bore shine was meant to do....