That's right I want to re-chamber a 280 to 7x57. Long throated, how much barrel length will I lose? Captdavid

Since the 7x57 has more body taper then the 280 you would need to set the barrel back a lot. I'm too lazy to calculate it and haven't had coffee. I doubt you have enough shank to handle it. If you could the fit in your stock would be terrible. Buy a new barrel.

After coffee "eyeballing" it says you would need to set your barrel back around .7"

In most bolt actions if you were to cut off the shank and re-machine a new one, you can rechamber to the 7x57 with no problem. So you will loose the length of the shank, but we don't know what rifle you are starting with, so we can't say what amount you would loose. Less then 1" in any case.