Perhaps a shotshell actually behaves as we have always been told a brass cartridge does, i.e., that is enlarges upon firing and grips the chamber wall, thus preventing it from having as much rearward thrust. I was told for years that they do not, but if the video shows it remaining in the open chamber during firing, it must. What else would hold it in there?
The brass imprints that we see on the face of the standing breech may be simply caused by the enlarging of the head of the shotshell against the breech, and not so much by a rearward motion against it. Brass cartridges expand, then retract to closer to their unfired dimensions, thus allowing ejection. Maybe a shotshell acts the same way?
Very interesting.
SRH
