It is your setting on the crimp/seating die. Adjust the die to just touch the shell plate and back it out 1 turn. Then seat a bullet adjusting the seating stem till you get your OAL. Then back out the seating stem. Now put the loaded case back in and raise the arm of the press. Turn the die down in 1/8 turns slowly keep repeating this till you get slight crimp. Most do not crimp 223 but I do but I use the Lee factory crimp die. Onec you get the crimp you want push the case back up into the die and lock down the lock ring. Then with the case in the die all the way up no take your seating stem and turn it down to you feel it touch the bullet..and then lock the seating stem in place. Try another case and check the OAL again adjust the seating stem if needed.

Hope this helps