Hi...FYI bumper or decorative chroming is a corrosion / dressing up finish that doesn't wear well. Hard croming does wear and is the type of chroming used to rebuild aircraft engine cylinders and hydraulic cylinders. A hydraulic repair shop could probably point you in the right direction. Also, I was wondering, if you were with the firearm while the shop was doing the work, would it then be legal for them to work on it?