Been told those crescent shaped plates were placed against the inside of the elbow and not against the shoulder. Haven't read any documentation or diaries or contemporary texts on the issue, but this is what those who are more learned than I (and that's a whole heckuva lot of folks) told me.
BTW, the Great Plains is one great rifle.
Vigilantibus et non dormientibus jura subveniunt. Molon Labe!