Please note: in photo to the right above, 375 SOCOM (Left) vs 458 SOCOM (right) for size comparision

"One Cartridge". 375 SOCOM 375 SOCOM by SRB, loaded with a .375" or 375 caliber, 200 grain JSP (Jacketed Soft Point)  projectile, and “SBR 375 SOCOM” Head-Stamp. 

Please Note:  Because this cartridge is used in both a pistol or rifle firearm, it is listed in both Shooting and Collectible Pistol and Rifle Sections.

History of this cartridge: The 375 SOCOM (United States Special Operations Command) was introduced in 2016 and one of the latest cartridges for the AR-15 platforn rifle, see below info on AR-15 platform. The 375 SOCOM is a necked down version of the large 458 SOCOM, necking down the case mouth to accept .375" or 375 caliber projectiles vs. the .450" 458 caliber projectiles of the 458 SOCOM caliber cartridge.

History of M16, M4, AR-15 cartridges: The first cartridges used in the introduction of the M-16 rifle and later in the M4 and AR-15 platform rifles were 5.56x45mm NATO cartridge and .223 Remington cartridges. However in the past 20 years or so, many new cartridge calibers have been developed for the M16,  M4 and AR-15 platform: 6.5 Grendel, 300 blackout, 450 Bushmaster, 338 Spectre, 458 SOCOM, and new 375 SOCOM and many more.