got to go, the 223 is a great little cartridge. Maybe it has something to do with its parent design the 30-06. No it doesn't use the 06 case but it shares an almost identical profile but smaller.
Some things just work no matter how hard folks try to screw them up. The 223rem or 5.56Nato cartridge is one of them. I have played a lot with this little gem. I have played with everything from Unique and 2400 pistol powders to 700X shotgun powder and close to a dozen different rifle powders from 4227 to H1000. All of them worked well with my test base of bulk 55gr Remington spire point bullets. I used magnum small rifle primers in IVI cases and loaded them all to the same OAL. I would do 100 rounds at a time. Of course this wasn't all with the same powder. I would make up 4 different loads of 5 rounds each to check over my Chrony. Then take them to the range for testing. Lots of different velocities and pressures as well as points of impact.
If you decide you want to try something like this make sure you start with the lightest load first and work your way up. Just common sense but I am always amazed at how many people just go straight to the max load in their manuals then add a bit more. If you have a tight enough chamber and a strong rifle of modern design it may be safe but if you don't know don't do it.
After all was said and done there were a lot of very suitable powders that were very close in performance. The two shining stars were BLC2 and Win748. Varget and 748 were almost identical. BLC2 gave me the best overall performance with the 55gr flat base Remington made spire points. I bought 10,000 bullets in bulk from an auction about 20 years ago. They were all from the same lot. They were very cheap. I paid under $200 for all of them after taxes and auction fees. I remember the auctioneer asking me how many 1000 count boxes I wanted at the price I had bid and I took all of them.
That was all I was interested in at that auction. There weren't any other firearms related articles at that farm auction so I paid up and left.
Anyway, if you can find the powder you like as well as the bullets you like all will be well.
The nice thing about the 223 is that depending on the rate of twist it will digest anything from 40 grain bullets up to over 100 grains and do it well.
It is fantastically versatile in that you can mix and match components and still get great results. If your pennies are tight it's amazing how well the cheapest stuff on the shelf shoots. If as you indicate hand load goes again, the cheapest stuff shoots very well and in most cases works just as well as the pricier components.
IMHO it's one of the best cartridges out there. With the proper bullets it takes Deer and even Black Bears out to a couple of hundred yards cleanly.