Same problem with some 357 Mag 125 gr FTX fired out of a new 627-5. I had just bought this box of ammo within the last couple of months.
While the new ammo loaded smoothly, I had to push the ejector rod on the side of the shooting bench to eject the spent brass. Other brands of factory and reloaded 357 ammo ejected easily.
After I got home, I measured the remaining 20 unfired rounds out of that particular box and compared them to 100 FTX rounds I'd bought last year. I checked the diameter midway down the shell case below the bulge of the bullet. The new sticking ammo measured averaged .376 inches compared to an average of .374-.375 on the older ammo. I also compared the diameter of the new fired cases versus some older once fired unsized FTX fired cases that I was saving to reload - new .381 vs old .379. Just out of curiosity, I took the new and older once fired casings and tried them in my M66 and M686. Same result - the new casing would not fit in the cylinder (unless I wanted to whack it with a hammer, which I didn't) while the older casing fit flush and ejected easily.
At least in my particular case with my particular ammo and guns, it looks like that miniscule increase in case diameter after firing is causing the shells to stick. And I had not been firing 38s in my 627 before I tried the 357 FTX.
I plan on contacting Hornady on Monday. I've never had any problems with their FTX ammo before (357, 38+P, & 45), so I'm sure this is just one of those irritating things that happen on occasion. Plus it shows why it's a good idea to check our weapons and ammo anytime we make any changes. Not to mention, it's just fun to go shooting. By the way, the lot # on my box is 3110983.
Pete