Yep..........the grand total of "any load book" is limited at best.
Even your own data shows speeds of less than 140 fps difference. Hence the HUGE difference.
The only real HUGE difference is that the typical .223 WSSM is chambered in a faster twist barrel making it more suitable for heavier bullets. The things I shoot with a .224" caliber rifle don't require heavier bullets.
The original question "is it a good caliber"........my answer yes..........do I want one in place of my 22-250 AI.........not a chance.
Not sure on your math bud.
223 wssm 22-250
H414 50.5 4301 62,400 PSI H414 41.0 3933 47,100 CUP 368 fps difference
H380 49.3 4292 62,300 PSI H380 41.0 3855 39,200 CUP 437 fps difference
VARGET 43.5 4278 63,800 PSI VARGET 39.5 4135 51,100 CUP 143 fps difference
BL-C(2) 46.2 4352 61,800 PSI
H4895 43.0 4320 62,900 PSI H4895 37.0 4060 48,700 CUP 260 fps difference
average of 302 fps for the four max loads.
Personally, I believe the round is hype. What about barrel life? I sincerely doubt you could get 4 or 5 thousand rounds down the tube, accurately (hold a 1" group at 100 yards).
Couple this with the expense of brass and the cost for the amount of powder to achieve these unreal speeds....better off to go several different routes.