I just purchased stevewhr's 45-70 cowboy and was taking stock of my reloading supplies. I am a rookie reloader. I have a box of 1000 old remington kleanbore primers No. 9 1/2. I do not know how old they are. Price on end of box reflects 9.95 looks like it was marked up from 8 something. Inside the flap of the individual boxes is 393-5061. Is this a date code? I am wanting to start working up a load for the long range dinger ringing. Should I use these primers? Would they act differently than newer primers? I got these and several boxes of pistol primers when i purchased my first used reloading press. The pistol primers are CCI and they are still ok.