Oakawbow is correct, no cant blocks are allowed and if a fore stock were purposely built to act as one it would be disallowed. As said the game was designed to allow anyone with an offhand rifle that meets the weight requirement to play. there are two classes, one is the Hunter class for rifles 10# or under with open sights and the other is an Open class for rifles 13# or under and using peep sights. That allows anyone with a TC, CVA etc to not have to have a purpose built rifle. Rules have been established and accepted by the NMLRA and I can forward a package of information to anyone who wants one.
Mark