If you go too low with your load, the primers will back out and lock up the cylinder, since it's the pressure inside the case that reseats the primer after it backs out of the primer pocket upon detonation. The burning powder's gases need to build up enough pressure to do this, and if you go much lower, there won't be enough.
The other problem you'll face is sticking a bullet in the barrel, since there won't be enough pressure to drive it all the way to the muzzle. If you don't notice that you've got a bullet stuck, and fire the next round, there's a good chance you'll bulge your barrel.
I think you're about as low as you want to go, though I've fired literally thousands and thousands of round with that powder charge and the 148 gr. HBWC bullet, but the volume of the case is reduced considerably when the bullet is seated flush with the case mouth.
Hope this helps.
Fred