Yes, you are reading that correctly, but I think the problem is your twist will be too slow for the heavy bullets, not too fast.
For the .223 anyway, a 1:12" twist is versatile and will allow up to probably 60-64 gr. bullets. A faster twist is needed for heavier bullets and for the 62 grain steel core military rounds due to their length, which is as long as most 70 gr. bullets. A 1:9" twist will let you shoot up to about 73 gr. bullets. A 1:8" or even 1:7" twist is preferred for the 77 and 80 gr. bullets. Not sure on the 22-250, but I would be surprised if it wasn't nearly identical in its requirements as far as barrel twist. Velocity does play a component, so the 1:14" 22-250 may stabilize the same weight as the 1:12" .223, for example.