tomhargrove: something like that could be a real quick ticket to lost gun rights and possible jail time. There are certainly regulations covering such devises and such may even be classified as 'homemade' which may not be legal.
BATF most certainly has its regulations posted on-line - I believe all government agencies are required to do so. The regulations governing the issue at hand may even date back to the Gun Control Act of the 1930s. Check the regulations first - it may be a simple matter to resolve.
If you think it illegal surrender the frame (minus every single part you can salvage) or destroy it, cut your losses, purchase a legal frame from a legal dealer and re-build. Don't make a mistake that could cost you your rights. Mikey.