In summer when I use green leaves as wads, no worries about this.
For "proper ' wads, if they build up too much air pressure, (for the one over the shot) Bite them around the edges to nick them and they'll ram down smooth.
Paper works for wads, as does "Spanish" moss. All seem to shoot the same patterns as far as I could tell.
(Used the leaves so's not to set fire to the fields at harvest time.)
Best,
R.
Ed, Indeed. You beat me to it!