If memory serves hunting rifles must maintain their original configuration so I'm going to say no to using an after market thumbhole stock.
Factory guns with thumbhole stocks may be an exception to the above.
In the heavy rifle class (unlimited) they were allowed when I was shooting but there's a 10lb 2oz. weight limit.
Shoot them an email. They will fix ya right up. Ask for a rule book if would like to.
silhouette
nrahq.org
