Did you test them at full-lockup (trigger held all the way to the rear)? If you didn't that may be the source of the problem. Rock Island/Armscor revolvers use a modified version of the old Colt double-pawl lockwork (modified in that they replaced the Colt V-Spring with a coil mainspring and separate trigger return spring). This differs from the more common S&W, Ruger, Taurus, Rossi, and Charter Arms lockworks in that the Colt and RIA hands stay in contact with the ratchet throughout the trigger stroke (S&W and Ruger hands leave contact with the ratchet after the cylinder stop engages the cylinder). This is why, at full lockup, an older Colt revolver (and by extension, an RIA) should have no perceptible rotational play in the cylinder (sometimes called the Colt "bank vault" lockup) while many other brands like S&W, Ruger, Taurus, Rossi, and Charter: the Colt/RIA cylinder is being held in place by both the cylinder stop and pressure from the hand.
Because of how the double-pawl lockwork operates, there needs to be a bit of "wiggle room" in the cylinder when the hammer is cocked but the trigger not yet pulled because if there wasn't, the action would bind as the hand would still be trying to rotate the cylinder while the cylinder stop is preventing further rotation. I've seen several Colt revolvers that, if cocked slowly, didn't rotate far enough for the cylinder stop to drop into its recess in the cylinder but, once the trigger is pulled, the hand rotates the cylinder just that smidge further to lock into place properly.