[6] As the Chief of the Bureau of Naval Ordnance stated in his 1897 Small Arms report to the Secretary of the Navy, "In making what may appear a radical departure in its selection of a caliber smaller than as yet adopted elsewhere...the Bureau is convinced it is looking to the future … it is surely wise to attempt to advance with one stride as far as existing conditions allow toward the goal to which the world is moving with slow steps.

[6] Winchester made the ammunition for the government,[1] which in turn provided each competitor with 6 mm USN cartridges and 0.236-inch caliber rifle barrels, the latter supplied unchambered and with receiver threads uncut.

[9] The new loading had an effective range (individual rifle fire) of 600-700 yards, at which point the blunt-tipped bullet rapidly lost velocity and energy.

[17] Contemporary medical reports of the day noted the 112-grain (0.26 oz; 7.3 g) bullet produced noticeably greater damage to tissue and bone than other contemporary military cartridges when fired at full velocity (2,560 fps), and the bullet's copper jacket frequently fragmented or detached entirely from its lead core after penetrating a hard substance such as bone or metal.

[19] Colonel-Commandant Charles Heywood of the Marine Corps reportedly refused initial deliveries of small numbers of Lee rifles to Marine battalions until he received assurances that an appropriation would be made to the Corps for at least 3,000 Lee rifles, improved target ranges, and enough ammunition to continue existing marksmanship training programs.

[25] The possibility that a 6 mm bullet might lack stopping power had been raised as far back as 1895 when the cartridge was in the process of being developed for adoption.

[26] However, the high velocity 6 mm round was ahead of its time in terms of powder technology and barrel steel metallurgy.

[32] Nevertheless, the board acknowledged the rimmed .30 Army round was less than ideal when used in modern machine guns, and the decision to adopt it for the Navy and Marine Corps might be postponed until a rimless version was developed (which would eventually take place in 1903 in the form of the .30-03).

[11][15] As a result, the light, roundnosed 6 mm bullet lost much of its effectiveness at 600–700 yards, while the 220-grain (0.50 oz; 14 g) round-nosed bullet of the .30 Army service cartridge was still considered effective at ranges of 1,000 yards or more, an important consideration in the days when rifle and indirect machine gun fire at distant targets such as massed enemy infantry was considered necessary.

[11][15] While by no means a universal opinion, the lack of shocking power of the 6mm Lee reported by some Marine units in combat may also have weighed against the idea of delaying a change to the .30 Army for all services.

[25] A further complication was that issues of barrel wear from the Rifleite smokeless powder and corrosive primer used in the 6 mm cartridge continued to plague Navy ordnance authorities.

[9] Rapid developments in military small arms ammunition would soon demonstrate the advantages of a magazine-fed rifle and machine gun cartridge with a rimless case and spitzer bullet, features not found in either the .30 Army or the 6mm Lee.

[27] In 1899, the Navy officially adopted the .30 Army cartridge for all small arms, though it continued to use the 6 mm for existing stocks of Lee rifles and Colt machine guns.

Unfortunately for Bannerman, the powder used in the 6mm Government cartridges had deteriorated to such a degree they were determined to be unfit for sale, and the company destroyed the entire lot rather than resell them to the public.

With a reputation for penetration and explosive effect, the 6mm Lee was reportedly quite popular as a hunting cartridge in Alaska and Northwest Canada.