BBF; I've done that for pistol loads. Seat the ball flush with the case mouth which leaves a bit of a groove around the edges. I just rubbed some lube, Bore Butter 'cause I had some, into the groove.
For SASS shooting there must be projectile visible in front of the case. My solution with blackpowder was to drop and compress a load with a wad cut from waxed milk carton, then a pea sized blob of SPG under the ball. You can size, in a regular lubrisizer, a ball to groove diameter. Frinstance, a .440, or even a .451, ball sized to .429 for a .44 case. Seat the sized ball 'til the bright band left by the sizer is pressed just inside the case. Smokeless doesn't support the ball from beneath like BP does, but a wrap of teflon plumbing tape will provide enough lube-action in a smokeless "fad powder" load.
For a better balance with the roundball in a pistol, try a .44 special or even a .44 Russian case. In a rifle, OAL and feeding problems will be a limiting factor.
For a .45 round, get a 155grain EPP-UGG, "Big-Lube tm" mold from Dick Dastardly or bullets from Springfield Slim. It is the same weight as a .45 roundball. They come as a 6 cavity LEE mould. (I wished they had one in .430, but no luck yet!)
http://www.biglube.com/In a pistol lighter projectiles almost always strike lower than heavier ones.
In a rifle there will almost always be a very noticeable difference, but each design of rifle is a law to its self.