A couple of years ago I read (don't remember where) a post that Wolf primers, part # KVB223M, were factory recommended for loading .223/5.56 and would stand up to higher pressures and not have possible slam fire issues in semi-auto rifles better than the "plain" Wolf small rifle primers (part # KVB223). I bought some KVB223M's and tried them with fine results. I have since loaded and shot thousands of them with no problems and will continue to use them. The boxes are marked with ".223Rem" on them. The Wolf regular small rifle primers boxes do not have ".223Rem" on them. Later, I found that Wolf also offers primers with a part # of KVB556M, which would SEEM to indicate use in 5.56 cartridges, but I don't know for sure and have not seen any boxes to know what is printed on the box. In any case, my use of KVB223M in .223/5.56 and 300 Blackout has given no problems, and I stocked up on them when the price went down.
Bottom line: I also have CCI #41's. I have seen no difference in performance or functioning or firing pin hits between the #41's and the Wolf KVB223M's; have never had a dud primer with them so far. In .223/5.56 I am using the Wolf primers for my plinking/blasting reloads with pulled bullets. I use CCI #41's with more accurate bullets for sighting in, hunting loads, and farm animal protection (I have read Wolf primer posts about duds, and for hunting or protection I want to minimize a chance of having a dud, thus the use of CCI #41's).
Edited to add:
This is from the maker of the primers. It reads that KVB556M is for 5.56 cartridges, and KVB223M is a magnum small rifle primer. Well, KVB223M works so fine for me, that I am sticking with it! (The formatting got kinda messed up when I copied and pasted, but it is still readable.) The part numbers that have the "E" in them refer to lead free primers. The "4,43" or "5,33" refers to the primer diameter in millimeters.
www.flame.murom.ru/en/default.htm
Small PistolKVB-9KVB-9E4,43For Standard Pistol loads
Small PistolKVB-9SPKVB-9ESP4,43For 9x19 NATO cartridges
Small Pistol MagnumKVB-9MKVB-9EM4,43For Magnum Pistol loads
Large PistolKVB-45KVB-45E5,33For Standard Pistol loads
Large Pistol MagnumKVB-45MKVB-45EM5,33For Magnum Pistol loads
Small RifleKVB-223KVB-223E4,43For Standard Rifle loads
Small Rifle MagnumKVB-5,56MKVB-5,56EM4,43For 5,56 NATO cartridges
Small Rifle MagnumKVB-223MKVB-223EM4,43For Magnum Rifle loads
Large RifleKVB-7KVB-7E5,33For Standard Rifle loads
Large RifleKVB-7,62KVB-7,62E5,33For 7,62 NATO cartridges
Large Rifle MagnumKVB-7MKVB-7EM5,33For Magnum Rifle Loads
50 caliber Machine GunKVB-50KVB-50E8,02For 50 Browning Machine Gun