My CBAC Colt M1861 has no crown, either. It shoots about as well as any handgun I've ever owned, allowing for the rotten sights.
If you decide that you simply must crown the barrel, DON'T use your files...that's definitely not how it's done. Ask your gunsmith or get BW to tell you how to do it yourself...if he won't tell you, I've got his post archived. Ask me.
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