Wow! I can honestly say, I don't know anyone that shoots 41 rimfire in cowboy action. At 100 rounds per match and three or four shoots a month, that's a lot for me. Not to mention a little practice.
I'm with you first place I would check is Navy Arms. Otherwise, Gun List has listed:
EXTINCT AMMO...41 rimfire short,41LC call Dick 914-331-1239
2ND AMENDMENT...1800 kinds of ammo...www.ammunitions.com or e-mail and ask firstname.lastname@example.org
WINCHESTER FACTORY AMMO...41 rimfire $22.50
[This message has been edited by Ned Roundtree (edited September 15, 2000).]