If you are looking to up grade an earlier Webley this might be what you are looking for:
http://www.collectiblefirearms.com/PistolsWebley.html
http://www.collectiblefirearms.com/PistolsWebley.html
Does anybody know if these parts will fit and work on the older MK I, II , III , IV ?
Does a modified mk1 with this mkIV barrel and cyl. Would be still antique ?
Yes, it would still be an antique as long as it retains the original frame.



























