'BillBlab' - Welcome to the KCA Forum.

The 'truth be told' the U.S. Krag was designed to feed cartridges with a 220 grain Round-Nosed Bullet, seated to an approximate, 3.089 inch, over-all length.

The position and slope of the case-shoulder, also plays a role in the smooth feed of cartridges.

Many U.S. Krags are tolerant of different bullet profiles and shorter over-all cartridge length.

Sometimes changing the left side-plate can make a Krag more tolerant in feeding non-standard rounds.

When a cartridge is 'short', it may move forward in the magazine. When the bolt makes contact, with the rim of a cartridge that is too far forward, the case shoulder can hang up on the lobe on the interior of the side-plate.
This can cause a jam or the cartridge to 'dive'.

Bullet profiles, like 'Spitzers', can hang up on the rear edge of the barrel-breech.

Some Krags seem to eat anything.

Tell us more about your 'dummy' rounds.
Pictures of everything always helps solve a problem.