From what I have read the lake city brass has a little thicker casewall. One post said something about one brass being able to fit up to almost 5 grains more powder in a commercial 223 that was converted vs lake city. Would have to search around to find it but I will not be running real hot loads anyway since most of what I handload will be for fun anyway. I know that a lot of people posted about the "x-treme" bullets copper plated 150 grain 308 bullets being pushed over 2000 FPS (in a 308) without any issues even though they are rated for no more than 1500fps. At 10 cents per bullet they will be great for a plinking round and a lot of people are begging X-treme to make a 220 or 240 grain bullet.