On 'Military Surplus Collectors Forum' there is a very useful (copyrighted) post by Peter Laidler on "CHS" (cartridge head-space) in the Lee-Enfield.

IMHO - This article (pertaining to the rimmed .303 cartridge) offers some insights into head-space with the U.S. Krag-Jorgensen rifle and carbine.
(Note - The L-E bolt does have a separate & replaceable bolt-head).

Google Search: Peter Laidler on-line index

select: Index of Peter Laidler's on-line series of articles

scroll and select: Cartridge Headspace (CHS).

(p.s. - Mr. Laidler, age 71, is currently undergoing a legal case in G.B., so there is a lot of unrelated 'search stuff').