'King carp' - Your brass muzzle-cover/front-sight protector is the Standard Issue one for the U.S. Krag rifle. It was adopted and manufactured at Springfield Armory in the early 1900's. This device sells normally for around $65.

Your first posted photo was a bit fuzzy and fooled me. It looked like one of the private commercial covers used by some competitive shooters back in the early 1900's.

Your Sling, Butt-Trap - Sectioned Cleaning Rod, and muzzle-cover, are nice accessories, that easily add $250 to the value of your Krag.

FWIW - If you need an original Krag Oiler (for the butt-trap), Grandpa's Gun Parts has them for $20.