? Never heard of a 5 thou increment. 10 thou yes. 20,30 40 60 80 thou. Some engines pistons can have sizes up to 120 thou. Is the marking impressed or etched? 0.85 would seem more appropriate, it may be a part number? or a fitter id number? or maybee they did actually make one...the best thing to do it measure the bore to make certain. is the chamfered lip still on the bottom of the bore this will tell you straight away. If this is the case...Get a new barrel.they are so easy to come by and probaly cost you nothing...:)
