FWIW, I have found that the 38/357 cases can be a little temperamental in moon clips. (Much more so than rimless cases like the 45acp/9mm) Specifically, if the clip isn't seated RIGHT AGAINST the rim, the rounds can get cantered and not want to go into the cylinder as a group (of 6/7 or 8). This misalignment can also bend the clip. A tool will help ALLOT with getting them right but even then, I have a process to assure they are right. Namely I stand the clip full of rounds on a flat surface, (bullets up, clip side down) and try to spin /move each round individually within the clip. If they have enough play to spin a little, they usually are seated right. IF they don't, it takes a push down on the clip with a screwdriver tip (on both sides of the round) to seat them correctly. ( You'll feel it pop into place.) Finally, I like to keep a open revolver close by to drop fit each loaded clip into the cylinder. ( Yea, I know they make a tool for this too but I find it unnecessary.) If you have any fitment issues, this last step will find them.
p.s. I would suggest that a rubber band or tie wrap run from the hammer , through the frame and back around the hammer will keep the cylinder from closing while you fit check.