Hopdoc,

The reason some PH's still prefer their clients to use only solids on buff, especially in thick cover, is that a good non expanding solid can be counted on to track straight. The deflection off of ribs and shoulder blades has been cited to me as a particularly good reason to use a solid, especially when sooting at an angle from the front.

I'd note too that the solid on a broadside shot will exit almost surely.

JPK