I just purchased a new to me, non G2 contender. It is an easy open frame with the 3rd variation hammer. I just bought a 10" .38 special octagon barrel, and it won't fit! It feels like it gets jammed into the gun, and the barrel won't release to break open. Am I missing something? My other two barrels go on and off without a problem. I looked at the lugs, and they are slightly different. The barrels that fit, have an "E" stamped on the underneath, and the .38 has a "G". Any help is appreciated.