stanc Wrote:A fact that almost certainly does not matter. In the last 125 years, the US Army has never adopted a new cartridge to upgrade old weapons.
Not true. After the civil war we converted the muskets in inventory with the 1865 Allen conversion which is better known as the Springfield Trap door rifle.
https://www.youtube.com/watch?v=jckv3dfwvSY
Correction, you stated in the last 125 years so you are correct! A case could possibly be made for the M-14 since it is an upgraded M-1 Garand but that is conjecture on my part.