I have a friend who loads 150 gr Hornady RN bullets and routinely wins matches with his Krag.  Now I realize that this is a RN vs a Spitzer... however the 150 gr RN is short enough to present quite a jump to the rifling in the throat.  I've tried them and couldn't get enough accuracy with them to make it worth my while... but we all know that Krags like what they like, and his Krag loves 'em!

I also know guys who use A-Max bullets, Match grade HPBT... etc.  Bob Wolfe (madsenshooter) often experiments with different bullets and loads for his many Krags too.

Haven't messed with the 155gr.  I've got some good 100yd groups with lighter bullets 123s, 130s and 140s, but they don't seem to be willing to hold the bull at 200, or I'm just getting too old and visually impaired to keep shooting.  I'd think the best bullet to eliminate jump would be the Hornady FTX 160gr for the 30-30, even they would likely have some jump, but I can't say for sure as I've not tried them, they're too pricey for me!  The only bullets I know of that will eliminate jump, while maintaining a short enough OAL to function through the magazine are cast bullets, like the 311284 or the NOE 316365 spitzer (only shot through a .310 groove diameter rifle), maybe a 311299, which I don't have.   Even Hornady RN 220s have more jump than some realize, but the shank is still in the caseneck when the bullet starts to take the rifling, minimizing any misalignment that might occur between caseneck expansion and the bullet hitting the throat.  After experimenting with the lighter bullets, I'm beginning to feel the old timers, like Whelen were right.  He said 172s and up, back before 168s were available, so I'd guess 168 and up.  I can't say how the FTX would be feedwise.