DRB
These Sub-Caliber Cartridges are based on the .30 Cal Army case (30-40
Krag
). “They were designed to be fired from sub caliber barrels mounted within or on the outside of the main artillery gun tube”. The first of these sub-caliber cartridges were developed in 1902. Some had enlarged primers to be used with the standard artillery firing pin and some had 0.317 dia Berdan primers. Some had typical .30 Krag projectiles, but starting in 1924 the some of these sub-caliber cases were loaded with the 1924 National Match 172gr., gilding metal-jacket, boattail bullet. This loading was adapted in 1925 as the Cartridge, Sub-Caliber, Cal..30, Model of 1925. Beginning with Lot 30, (FA 28), M1ball bullets appear to have been used.
These cartridges were designed primarily for the sub caliber tube used in the 3-in. seacoast gun.
During 1927-27 a quantity of Model 1925 sub caliber ammunition was released to shooters thru the DCM as a substitute for Cal. .30 Ball, M1898 Krag cartridges, which at that time were not available.
All of the above is from “History of Modern U.S. Military Small Arms Ammunition” by Hackley, Woodin and Scration, Vol. I. This volume has a lot more information on this cartridge, I have given you just a bit of this information.
DRB, there is a illustration on page 93,, very similar to yours but it was loaded on Mar 20, 1923 and is from Lot 20
Any one with even a passing interest in U.S. Military small arms, should have all three volumes. Vol. I & II are available, Vol. III is finished but not yet printed.
Added note: this ammunition was available thru WWII.
45B20