Brassman is good but I've generally had to process his brass. Gunbroker is a great source of both fully processed and brass with crimped primer pockets. Federal brass is generally considered too soft and with too small a volume for loading with the 79 gr bullets now being favored in 3-gun matches. Lake City is my favorite. I have a bunch of Federal that I like for light bullets as it is very consistent.
Google Cheyenne Brass located in Cheyenne, WY; I've bought once fired .223 commercial brass from them before. They also sell other supplies. Once fired commercial brass will save you lots of money versus new brass. Another hint, make sure you small base size each shell if you're shooting it in an automatic. Once you've fired the reload in your gun I then only neck size the shell (this saves you the lube process and thus saves time) which requires the purchase of another die but it's well worth it. I also invested in a drop-in gauge to check the shell after firing. So far, after reloading 5 times, no stretching of case and 100% reliability. Darrell
You need to full length size if it is for an AR- or you probably do- I guess you could try neck sizing - if you are just going to use it in one gun and see what happens-- chrome chamber- you might be ok because brass shrinks slightly before ejection