I found that ALLOWBOUNCEONACTORS only does half of what I want it to: While it does allow a projectile to bounce off of non-shootable props, it only checks whether the actor bleeds or not. Hence, it will bounce off of non-bleeding but damagable actors. (Barrels, Sabreclaws, and Pods, and Hexen Pottery are a few examples.) I'd suggest another flag to compliment it, which would cause the projectile to explode as normal on actors that are SHOOTABLE and not DORMANT.
I can't think of a good name other than DONTBOUNCEONSHOOTABLE.
Obviously, this would be pointless when combined with BOUNCEONACTORS, so the latter should probably have "final say" on whether the projectile should bounce.