Vlad, I do not consider RCBS dies as the end all, be all dies that some do. I've had some issues with their sizing dies in the past and now prefer Redding dies, especially for .223. I'm not suggesting anyone needs the $250 competition dies, but I find their $40.00 basic dies provide a good return on investment.
Regardless, you can probably fix your problem with your existing dies by screwing them in another 1/2 turn and resizing your brass. If that doesn't fix it, you have an issue with the OAL, and may need to screw in your seating die a 1/4-1/2 turn.
Isolate and adjust one variable at a time, and see which one fixed it.
