Little known but very good western from 1991, is “Into the Badlands” with Bruce Dern. His character does a cylinder swap with a Colt Walker (holding the wedge between his teeth to keep his hands free) during a gun battle.
Also, don’t forget Will Munny (Unforgiven) begins the film with a Model 1858 Starr revolver, set in 1881.
And although not a muzzleloader, here’s a size comparison of the aforementioned .50-140 with:
l-r .22 short, .22 lr., .56-50, .45 Colt, .45-70, .43 Spanish, .450-577, .50-140 (3 1/4”).
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