1 - Inadequate end shake. I know that is uncommon and few folks consider the possibility of too little as there is usually too much, but it does happen on rare occasions. Sometimes due to inadequate fitting and occasionally due to build up in the cylinder center hole keeping the bushing from seating properly.
2 - The face of the cylinder is often not square to the axis, causing run-out of the face as you turn. Very possible that one side of the face is touching the rear of the barrel as it heats up/expands from firing.
3 - The cylinder base pin may be a little loose allowing some wobble. That won't usually play into binding, but it could under some circumstances.
4 - Rear face of barrel may not be square, leaving a high spot that can grab the cylinder as it expands from firing.
5 - Combination of the above.
The easiest to fix is end shake. Clean the cylinder bore really well, check the bushing for full seating, and adjust the fit as necessary to get the minimum amount of end shake to accommodate heat expansion without binding. Next is the base pin. Belt Mountain sells oversized ones that work really well and are a great upgrade. Brownells sells a kit to recut forcing cones and one of the cutters faces the barrel. A lot of money for one gun, but you might be able to rent it from 4D Reamer Rentals or one of the other tool rental houses. The cylinder is a little tougher to do. You need a lathe (or mill) and the appropriate fixturing to indicate and face the cylinder to remove any high spots.