You most likely answered your own question when you said it was reloads causing the problem, but not factory loads. "Stuck slide" sounds like an oversize case, or bullet seated to long. Remove the barrel from your pistol, and do the "plunk" test. Drop a couple of your reloads in, and see if they fall all the way in as they should, or if they hang up before fully chambering. A lot of guys like the Lee Factory Crimp Die for bringing their reloads into proper spec.
Larry