Thank you for the kind comments. I'll be nagging Andy Callan to come up with both a suitable scenario for Billhooks and some adjusted rules. I'll post up here once I have something.
I am curious as to whether guns like these would have seen service in any sort of battle rather than sieges. On the face of it, they were hardly mobile but if you had one in the baggage train, why not use it? For example, in the 2nd battle of St Albans, Warwick had set up defensive lines, only to be out flanked. You can just imagine the Yorkist army digging in this sort of gun thinking that they would surprise the Lancastrians...
Wishful thinking on my part but enough to concoct a reason to deploy it!
Thanks again,