Speer does make a 55 gr TNT/ HP, that is designed for the 22.250 and the Swift....
Those might do better holding up in a fast twist 223..... they are available in the 1000 pack...
They WERE available a few months ago..........don't see any available right now.....
Kind of designed for the 22-250 & Swift. Still can't push em to max velocity that these 2 cartridges will run em.
Edited: They used to have a velocity cap on those 55s, just looked and couldn't find any information on that. Maybe they beefed em up a fuzz. I was thinking they had a cap of about 3400 when I was shooting them.
I did shoot the 55s in a 9 twist 223 several years ago, very good mist factor for what a 223 can run em.