SKULLANDCROSSBONES65,
I don't know what number of rounds you put through the chronograph to get that number. If it was 10, then your standard deviation will be about 1/3 the extreme spread of 60 fps, or about 20 fps. That's neither remarkable nor terrible.
The first trick for consistent velocity is to always have the powder in the same position in the case at firing. If the load is compressed, it will stay put, but if it isn't, always handle the gun and cartridge to place the powder over the flash hole. That will provide maximum pressure and the most consistent ignition. If your range's rules allow it, chamber the round, tip the muzzle up and tap the butt of the stock to set the powder back and then lower the gun slowly to level to shoot.
If you want to do better than that gets you, pay extra attention to ignition. Debur the flash holes and prime carefully to compress the primer between 0.002-0.004 inches (.05-0.10 mm) beyond the point where you just feel the primer's anvil making contact with the bottom of the primer pocket. This is called Setting The Bridge (of priming mix between the nose of the anvil and the bottom of the primer cup) or Reconsolidation of the primer. It is seating them pretty hard, but that specific range was found best for ignition reliability and consistency by U.S. Naval Ordnance at Indian Head back around 1980, and it still seems to be best today.
You can also do this by the brute force feel with some success:
"There is some debate about how deeply primers should be seated. I don’t pretend to have all the answers about this, but I have experimented with seating primers to different depths and seeing what happens on the chronograph and target paper, and so far I’ve obtained my best results seating them hard, pushing them in past the point where the anvil can be felt hitting the bottom of the pocket. Doing this, I can almost always get velocity standard deviations of less than 10 feet per second, even with magnum cartridges and long-bodied standards on the ’06 case, and I haven’t been able to accomplish that seating primers to lesser depths."
Dan Hackett
Precision Shooting Reloading Guide, Precision Shooting Inc., Pub. (R.I.P.), Manchester, CT, 1995, p. 271.
Figure you are going for a percentage of Muzzle Velocity (MV). Hackett's '06 10 fps SD is just over 0.36% of MV at 2750 fps, a typical velocity for that gun. If your 223 Rems have an MV of 3200 fps, then an SD of 11.6 fps is equivalent and you are looking for an extreme spread of about 35 fps.