Rock185
Member
Ritt, I don't know what the weight rating is on the factory FM, but the Browning/FN uses a 32#. It is quite heavy and the C&S may be a similar weight. I have used the 28# Wolff mainsprings in my Brownings, and have never had a misfire/light primer strike, etc. This,even with the Winchester NATO 9MM ammo, which seems to me to have a slightly harder primer...