Funny you ask, because I did this weekend with 204 Ruger. My identical load is 3820 with CCI 41s, and 3780 with Winchester SRP. I didn't check against other CCI primers, though. I generally get the same velocities with WSRP and 200s.
FWIW, and I don't know if this goes for others, I have a hard time getting low SDs in 223 bolt face cartridges. On the other hand, I don't work too hard at it because they aren't things I shoot out all that far, but I consistently get mid 20s in 223 bolt face, and 4-9 or so in 308 and larger bolt face. I mention that because the 41s give me better SDs than 400s in general.
Ack, now I see you are asking about 34s. My experiences have been good with them as well, but I have less data as I load and shoot less large frame semi auto.