Welcome, Jason,

You ask a good and important question that ties into the vast array of Krag sight changes that occurred over its 12 year life span along with subsequent front sight blade changes that corresponded to the rear sight used. The carbine sights were set up to shoot differently than the rifle sights because they had shorter barrels and were designed for shooting, generally, at closer targets. So, the carbine rear sight is supposed to use a specific front blade. Whenever you change from one rear sight to another, you risk having a mismatch and not being able to shoot to point of aim.

This also depends on what ammo you use. The carbines frequently are shot with a lighter bullet and the rifles usually are shot with a heavier bullet. This is not absolute but a general design and standard practice. You can use whatever you want and work up a good load for your specific firearm with powder and bullet.

But, we would need to see good pictures of your Krag and sights to answer more specifically. Good pictures include the muzzle and front sight from different angles as well as the Krag receiver and each sight.

Welcome to the wonderful world of Krags! More info to follow.