The case is forced out of the chamber back against the breech plate which causes the primer to be pushed back into the primer pocket.

Otherwise every time you fired a round in a revolver the cylinder would bind up, just like what happens when you fire a "primer only" round because:

-the primer's pressure forces it out of the pocket (because the primer pocket's flash hole restricts the pressure) & it stays out, against the breech plate because there was no powder charge to force the case back into the breech plate resetting the primer back into the pocket, flattening it, & putting the tell-tale "forensic" marks on it from the breech plate's imperfections.

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The cylinder is essentially "floating" on the yoke's barrel.

The yoke's barrel gets pounded, & flattened, (causing excessive clearance & endshake) not by the cylinder (& rachet face) being forced rearward against the breech plate (which is away from the end of the yoke barrel) but by the frame of the revolver recoiling rearwards pounding the attached yoke's barrel into the the cylinder's innards.

The cylinder being harder wins, the end of the yoke's barrel being softer loses.

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Waiting for the break of day