About five years ago I sent a 357 50th Anniversary to Hammilton Bowen for his Western Classic Conversion along with a Deluxe tune upgrade and a few other things he found needed done once the gun was there. I left this gun a 357 with the barrel staying original except for some reshaping of the front sight. After looking at the roll markings on the top of the barrel and the warning on the side of the barrel for four years I decided it all had to go. I contacted Mr. Bowen about barrels he had on hand and for a very reasonable price he sent me an almost pristine 4 5/8" OM 357 barrel. I got the barrel installed and had to set it back a bit to make it work. Then the suprise not once did I check the diameters of the two barrels against each other. The OM barrel is about 1/32" smaller than the NM barrel and now leaves a gap between the ejector housing and the barrel that tapers from nothing by the screw to .016 in the back where the ejector housing fits into the frame. I looked at jurry rigging the ej housing but think now I'm going to build a custom ej housing to fix it. If I would have done all my homework I would have caught this before I started and would have just polished the exhisting berrels roll markings off. It does look nice with the OM markings on the barrel thou. Oh well I hope this information helps someone else in the future and they remember to go one step further than rep1954 in the thinking process before they start wrenching.