Mike, I think you're on to something,there is a slight bump in the lower rib no where near the lug (muzzle end),but it suggest's a rib re-lay may have happened in the past...I'm going to pull out the ejector /extractor arm's just to see this evening ,I'm not fussy on stripping and re-laying that rib ,but although I am capable I will only do it as a last resort.

Thank's for the help guy's.
Chris