Well PDshooter, H335 is one of the powders that I have heard works real well in .223, so I think you should be able to play with it a bit and get some better results than what you have seen so far.
As Walter mentioned, you may want to play with seating depths... that can make a huge difference in accuracy. Have you set your seating depth by the following method?...
Slightly squeeze the neck of a spent case so that it snugly grips a new bullet when you insert it into the case by hand. Gently chamber this dummy round. The idea is to have the bullet forced into the case when it contacts the rifling lands. Gently remove the round and measure it with calipers. (repeat this a few times to make sure your measurement is consistent) Now you know the max length your round can be... back off a little and you should be in the ball-park as to your seating depth. Play around with this and see what gives the best accuracy.
Definately play around with the powder charge. If you haven't been experimenting with this, then you will be surprised at the difference it will make. (Be sure to start low and work up to max charge for your rifle... don't exceed published max loads)
You said you are using military brass... keep in mind that the case volume is less with MIL brass, so your max will be with a lesser charge than commercial brass.
Just a few other things:
- make sure your brass is all trimmed to the same length.
- neck sizing only after your brass has been fired in the bolt rifle you are reloading for will give better accuracy.
- clean out primer pockets and debur flash holes.
If, after all the above, you still don't have good accuracy results, you may want to experiment with different powders and/or bullets.
..just my .02