On topic and more to say...
I haven't seen one of the new 'factory' j-frames cut for moonclips, but I do have a 640 that was cut by Tom over at TK custom. His 'newer' clips are stainless but they are still quite fragile and bend easily. It doesn't take much for a slightly bent clip to hang up the cylinder. I've tested each clip I received and I have noticed that the tolerances vary. Some fit the ammo better than others'. To that end, some ammo fits much better than others.
Anyway, try another clip or two as mentioned above. Tom does offer a flatness tester, which is essentially a machined piece of flat stock. I have it and it does tell the story as 2 out of 20 were bent right out of the package. Yes, they are going back for replacement. Unfortunately, Tom doesn't currently provision a 'clip saver' tool for the j-frame so for now, it's a bit of a crapshoot.
For those interested, this is what you'll end up with if you jump in with both feet. Frankly, I experimented and discovered the blue moonclip loader to be bit cumbersome. I found that I can effectively 'hand load' all but the last round easier than with the loader. For the last round, it works and prevents bending. The stand-alone puller (screwdriver handle) works very well.
Summary: At nearly six-bucks a pop (shipped) these may not be the true cats meow for some j-frame owners'.
Regards,