New .308 Based Cartridge – The 375 RAPTOR

    Arne Brennan, arguably the real “brains” behind the 6.5 Grendel cartridge, has announced the release of his latest caliber, the 375 RAPTOR. Building on the knowledge gained from the 45 RAPTOR (an improvement over .458 SOCOM), the 375 RAPTOR is, in-short, is a shortened and necked-up .308 Winchester for the larger diameter “slicker” 375 diameter bullets.


    The .375 was chosen for a few specific reasons:

    1. .375 is the minimum caliber allowed for dangerous game in Tanzania and Botswana. If this is good for large foreign game, it will certainly be sufficient for all North American game.
    2. The bullet is already in common manufacture by well-known companies such as Nosler, Sierra, Speer, etc.
    3. It will work for both super and sub-sonic. Heavy pills such as 350 grain bullets are available from Sierra.


    Brennan’s company, North American Sportsman, LLC calls out a major points for the new caliber.

    1. Designed to work directly with .308 bolt-action and semi-auto platforms. Only a barrel change is required.
    2. Brass is easily converted from existing .308 Winchester cases without the need for saws.
    3. Runs at the full 62,000 psi pressure common to .308 Winchester.
    4. Works in common PMAGs (but requires some filing).
    5. Works with the complete range of ball and extruded powders.

    The caliber is releasing with full availability of reloading dies and reamers. Medesha Firerams has stepped up to support the custom manufacture of barrels, brass, and other items. 

    In 2014, we released the 45 RAPTOR which redefined the concept of a big bore modern sporting rifle with true 200 yard range capability.    Never one to rest on our past accomplishments, we continued the evolution of ideas and design with the result being the 375 RAPTOR – An evolutionary step forward in power that goes beyond any other big bore cartridge available for modern sporting rifles or short action non-magnum rifles.  

    • The 375 RAPTOR delivers 300 yard large game hunting performance with over 3500 foot pounds of muzzle energy and over 2000 foot pounds of energy on target at 300 yards in a typical hunting rifle configuration making it suitable for any game animal found in North America including Deer, Moose, Elk, Bear or Wild Boar.

    • The 375 RAPTOR is direct conversion for any short action rifle currently chambered in 308 Winchester requiring only a barrel swap whether your choice of sporting rifle is an AR-10, LR308, SR-25, G2, Remington 700 or Model 7, Savage 110 or Browning BLR.

    • The 375 RAPTOR delivers sub 1-inch 100-yard accuracy using hunting bullets, while maintaining a 300-yard terminal velocity of 1800 fps or greater for reliable bullet expansion.

    • The 375 RAPTOR maintains a +/-3 inch flight trajectory from the muzzle to 200-250 yards impacting a 6-inch diameter vital zone without hold-over or sight adjustment.

    • The 375 RAPTOR is easily formed by any hand-loader requiring only resizing and case trimming to complete the process of converting commercial 308 Winchester or military 7.62 NATO brass.   Conversion is so easy and options of parent brass so abundant, it makes producing native brass unnecessary.

    Those interested can learn more from the new 375 RAPTOR Website. 

    Nathan S

    One of TFB’s resident Jarheads, Nathan now works within the firearms industry. A consecutive Marine rifle and pistol expert, he enjoys local 3-gun, NFA, gunsmithing, MSR’s, & high-speed gear. Nathan has traveled to over 30 countries working with US DoD & foreign MoDs.

    The above post is my opinion and does not reflect the views of any company or organization.