I have a LK-93 that used the #11 caps I like it so much that I bought a case of #11 caps for it. I have taken several deer with this rifle and it always worked well. To hunt on government property around me you must qualify with the rifle you will be using, The 1 year I did this the requirements where, one must hit 3 out of 5 shoots on a paper plate at 50 yards. My first shot was center of the plate and the 2 ND was touching the plate, The ranger master looked at me and told me no need for me to shoot any more :grin:
I have since got 2 encore m.l. barrels 1) 209x50 handgun barrel and 2) a 26" 209x45 rifle barrel and the both use 209 primers. I do not see a way you could use a #11 cap on a break action barrel safely and still be reliable
I do know one advantage of using 209 primers, They are more water proof then #11. I have soaked a 209 primer in a glass of water for 2 hours and the thing still fired, the #11 did not