First off I would check the chambers and rim recess to make sure there is no crud build up, .007 is not very thick, that's about 1/4 of the thickness of a piece of computer paper. With the case spec's calling for a .065 and your rifle not closing completely until .058 there is something holding that case up. A chamber cast would be my next step. Do you know who built the rifle? If so I would contact him for advise.

Something else you could try. take something like a popsicle stick, cut the end square and scrape the rim recess, if there is a burr it will show up by stopping the movement of the stick, if its a burr the only recourse I can see is re-chambering,
Bob