Looks to me like you are pushing the CYLINDER backwards, toward the standing breech/recoil plate of the gun. Normally, when the gun is loaded, most of this space will be taken up by the rims of your cartridges.
If you mean the cylinder turning slightly as you cycle the action, then that is something entirely different. ANY gun will have some play, especially when the hammer is down and the trigger is not being pulled. The only play that you worry about is when you have the hammer down on an empty chamber and the trigger is held back, as in what the situation would be had you just fired a shot. In this condition, play should be absolutely minimal... but there still will be a little bit.
If the guns were made with NO play at all, they would not be as reliable as they are because the action would start to bind from heating after about 2 shots. And they would cost a LOT more.
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