After ~2850fps at max mag length in a custom freebore chamber I start popping some primers with crimped brass in hot weather with a 29.5 inch barrel. 2900+ is not realistic in a 223 with 88s IMO. That's the exception not the rule and is very likely not going in a magazine.
agreed.
To the OP, I would like to add that if your goal is to shoot a bullet heavier than 80 gr at speeds greater than 2900 ft./s, then you should be looking at cartridges other than the 223. Those expectations are just not safe.
ballistically speaking, a magazine length 223 sucks in the wind. If you want to shoot that cartridge then I think you have to just except it for what it is.
A phenomenally accurate cartridge with no recoil and great barrel life that is a handicap in the wind. I say this as a 223 fan myself.
Just my .02