yes the extra space is certainly a contributor, also a culprit on these particular shells in this or any 45 ACP revolver is the bottleneck cartridge design of their 45 ACP shotshells....not the plastic shot caps like the normal revolver shotshells
Attachment 51634
Just like the .22 Hornets in those short lived N frames, a bottleneck cartridge in a revolver gets pushed back and expands so violently against the firewall that the thing is deformed and the bottleneck expands partially into the cut part of the chamber and partially into the freebore part of the chamber and reforms itself to that new nearly immovable shape...it was a PIA