A few years ago, I tested the snapping a couple of caps or primers theory
in my Encore. A lot of people seem to think it makes a difference to snap
a couple of primers (inline) to completely dry remaining oil out of the
barrel after patching until there is no residue left on the patch. (Some oil
is bound to remain around the plug. Question is -- Is there enough oil left to
be absorbed by enough powder to make a difference? One more -- Will
blasting off a couple primers dry this oil out?)
In T/C's concave plug, firing off a couple primers seemed to make a
difference in that the first round hit at the same height as the second and
third at 100yds. In the flat faced plug, the first round hit a couple inches
lower, just as it did by firing no primers at all. Apparently the blast area
of the concave plug allowed the primer fire to spread and reach the area
in which any excess oil remained, while the flat faced plug would not.
Guess it should be noted that I spit patch between each round, at the
range or in the field.