I am new to the forum, so if this has been covered, I apologize. I have been reloading for a few years and have a procedure that works well and has been safe. Never had any problems with pistol loads or bolt action rifles, but the AR type of rifle, totally different animal. First problem encountered, lack of sufficient pressure to eject the spent cartridge, 300 AAC. Solved that problem with much experimenting different powder and charge size. Next problem, failure to chamber. After much studying on the subject found out "each chamber is different". Again had to go through the process of finding the correct neck size for my chamber. The standard casing sizer was of no value. Even though all would check ok, some would not chamber. Solved that problem with much trial and error. Now I have great 300 AAC reloads. Now on to the 223. No problem with ejection, but some, even with the same neck size will not chamber. All have same OAL, but again some will not chamber. The loads were 55 gr. JHP OAL 2 23. Now here is where the problem may be...various brass types. Any ideas.