A friend I shoot with had this problem in a 6" k frame a month ago. I have a Jim Clark 38 special long slide--made from a 38 super. I have to size my bullets to ..356. I let him have a 100 rounds & it fixed his problem. Even my .357 bullets would not chamber in his gun all the time. I took his bullets--.3575--& resized to .356 & everything is ok & it did not affect his groups.---I also have to use a taper crimp die on some 38 loads. -BY the way--The bullets that would not work in his gun worked in mine.-- JACK-