Disclaimer to begin with
, one thing I would suggest, if you were to purchase one, have the headspace checked or at least have it thoroughly inspected by a "competent" smith. These things are over a century old, seen who knows how many rounds, and like a .303 Brit, 8x56r Steyr and a x54r Russian, they headspace off the case rim. It's better too know, than it is to blow.
And it's not a good photo, but if you notice in the bottom photo, the bolt handle groove, it more or less acts as a very crude safety lug, as the bolt handle slot is notched into the receiver. Would I bet my life on it, absolutely not, but I also don't ever recall of hearing anyone with a Krag bolt shoved through their skull.
.30-40 Krag, .30 Army, any modern brand name made ammo should be safe. Modern ammo manufactures load a little below spec because of all the older firearms are still in existence. One of those nasty legal little words known as, liability. Another is the .45-70 Springfield, most run of the mill bla bla ammo is spec'ed for the old Springfield Model 1873 trapdoor. When in reality, you can get .45-70 Gov't ammo loaded approaching .458 Win Mag levels, just god forbid you touch that round off in an old trapdoor rifle. I've used .30-40 Krag 180gr HSM ammo for quite awhile and also used the regular plain Remington 180gr. It's also fairly popular as a handloaded cast bullet round, given the ammo is run in lots or not at all during peak times for other calibers.
Also, these were set up for 220gr bullets like you stated, so it takes some slight site adjusting to accurately fire the 180gr rounds.