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.


  • JimBobble

    As a fan of the .375 Ruger, this tickles my innards.

    • A.WChuck

      “See a Doctor if your innards are tickled for 4 hours or longer.”

      • Larry


    • The .375 Ruger seems like a very sensible round. A short action version of the .375 H&H seems like just the ticket for dangerous game on a budget.
      But the .375 Raptor uses widely available .308 brass. That makes it even more attractive.

      • Bevin I’m curious, what are the gun laws like in Taiwan?

        • Terrible.
          Gunpowder and guns were invented in China, yet nowhere in any part of China are individuals able to own guns.
          Not the mainland. Not Taiwan. Not Hong Kong.

      • Larry

        Bevin you are trying hard to get me into this little round, I like you, like my .375s and love the Ruger round.

        • The largest bore rifle I’ve owned is a black rifle in 7.62 NATO.
          But I would love to have a .375 bolt action sporter.

  • Rick O’Shay

    Well. Yet another round for the caliber hunt.

  • Spencerhut

    Didn’t these guys released the 450 Raptor a while back? If it’s the same folks the .450 Raptor went no where. I even tried to build one for a customer. Several phone calls and e-mail went unanswered. I hope they do produce it, and return the phone calls of people trying to buy it.

    • Joe

      Yeah, I liked the concept, but I’ve yet to see one.

  • alex waits

    I like the numbers, especially coming out of a 16in barrel.

  • Eric Strabel

    I love my 375 Ruger, but why would someone load a 375 bullet, designed for at least H&H velocities, into the 308 case when there’s the 358 winchester with bullets made for that velocity plus pistol/revolver bullets? Dangerous African game with an AR would be the only reason, I guess? Have at it Hoss.

    • BB

      Hunting a platoon of armed bears?

    • Subsonic hog hunting… let that sink in 🙂

      • iksnilol

        I’d use .50 AK then.

      • JSmath

        One of the first things I thought of, and then I remembered how few suppressors on the market would be compatible with this, either due to pressure or diameter. Curious what the Cosmic will do paired with it, but I have my expectations tempered between okay and decent.

    • FarmerB

      Yeah, and I’m wondering how many countries in Africa would allow you to turn up with an AR?

  • Duray

    How is the 45 Raptor an “improvement on the 458 SOCOM?” It’s faster, sure, but it’s a larger round for a larger gun. That’s kinda like calling the 300 Win Mag an improvement on the 300 Savage. It’s just a bigger round for bigger guns.

    • Christian Hedegaard-Schou

      Came here to say exactly this.

      If anything the .45 Raptor is an “improvement on the .460 S&W”. Oh wait. It uses the same load data. It *IS* a .460 S&W (just made for semi-auto actions).

    • Amanofdragons

      Same thing. Personally I believe it as a downgrade to the socom.

      • Sledgecrowbar

        It’s more powerful for the larger 308 AR action, but if you were looking for the advantage of the larger round for subsonic use, the AR-15 action would be smaller and lighter. I agree that it’s erroneous to say the Raptor is an improvement on the SOCOM, I don’t think they have anything to do with each other.

      • Anonymoose

        To be honest we should compare it to the .375 SOCOM.

    • Anonymoose

      Moar boolits per clipazine (20+ in a modified .308 mag vs 7 in a 30-round STANAG mag). Also it does a 300gr boolit at 100fps faster, and uses more common .452/.454 pistol boolits over .458 rifle boolits used in the SOCOM, .45-70, .458 WinMag, etc.

      • Christian Hedegaard-Schou

        .458 SOCOM gets 10 or 11 cartridges in a 30rd USGI magazine. Not 7.

        It gets 7 in a 20rd USGI mag.

        I would argue that .458 bullets are far more common and with a wider variety available than .452 bullets, since they run in weights from 200gr to 600gr.

        • Anonymoose

          Text amended. However, not many people are going to shoot >405gr bullets unless it’s a .45-70 (or anything over 300gr), and .452″ is easier to find cheap bullets and bullet moulds for. If you want to shoot 500 or 600gr bullets out of an AR platform it’s going to be very slow if not subsonic, but if subs are your goal, .458SOCOM is your cartridge.

          • Christian Hedegaard-Schou

            The whole point of the .$458 SOCOM was to duplicate .45-70 performance in the AR15 platform.

            I shoot 450’ers myself, and there are plenty of guys on the 458 forums shooting 500 and 600gr bullets.

          • glenn cheney

            HUMMM….We old school traditional platform types, lacking the sophistication youse guys have, we just use that ol’ time religion….450 Marlin…Awww, I know….What’s a 458 cartridge doing in a lever?
            I dunno, but, if ya’ get locked out of your own digs, forget your password, the 203x whatever battery just puked, someone shot the gate lock with a .22, I’ve found, that when you really really need it, (never leave home without it, hell no, it ain’t in my wallet) when you need breech birth…it goes horizontal no problem.

  • CS

    Is it subsonic?

    • Anonymoose

      With heavy enough boolits.

  • Kevin Gibson

    Exactly what will this do that a jillion other cartridges won’t? If anyone really thinks there’s a meaningful difference on game in the field…well, I guess they’ll be the suckers that buy it. The .358 Winchester already has that particular niche covered, and the .350 Rem Mag does it even better. Not sure why a slightly larger bullet would cause anyone to think that suddenly things will be “better”. The .358 Winchester is already an outstanding cartridge.

    • Vitsaus

      My guess would be heavier bullets in the AR10 platform than most loadings that .308 can handle.

    • Joshua

      well, as a letter of law argument, .358 Winchester is not a cartridge you can legally hunt heavy game in Africa with….. as was mentioned in the article, many African countries require a cartridge of .375 or above, so there’s that….

      mind you I wouldn’t want to take this out for cape buf……

      • Anonymoose

        A lot of African countries also ban semi-auto rifles for plebs, though, don’t they?

        • Joshua

          yeah, though from what I’m told that is more of a money thing, if you have enough money you can ignore that law. But having never lived there I can only tell you what I’ve been told

    • GOT12

      what will it do? it will cost 10x more to shoot, for some that seems to be enough

  • Mehul Kamdar

    Basically a shortened 38 / 375 Whelen. Let’s see how it is received . . .

  • noob

    in b4 “KABOOM: this guy loaded an AR10 in 308 with a mag full of 375 Raptor – photos to follow”

  • Amanofdragons

    Not to nitpick, but it would be a savage 10, not a 110. The 110 is the long action.

    • John Daniels

      Yeah, but if you put a short action cartridge in a long action rifle, you can load heavy-for-caliber bullets (in the case of .375″, that means up to 375 grains like Cutting Edge makes) all the way out to about 3.3″, which could be useful for subsonic applications.

  • I think that this is a alternative to the .375 Reaper that Whiskey 3 (John Culpepper) failed to bring to market with his “Less than Honest” business practices.
    Either way it looks cool as a big brother to the .300 BLK.

  • ??

    So it’s a longer .375 whisper with a shorter neck?


    No need for all the rounds.Why not put 200 grain Bullet in the 308.

    • Anonymoose

      Doubletap did it. Also, Hornady offers a 220gr .308 as part of their “International” line (which means you can’t get it in the US).

  • Why won’t people leave that poor wheel alone already, it’s been reinvented so many times the sad thing is practically square now.

  • Klaus Von Schmitto

    I think I’ll just stick with 358 MGP since it goes into an AR mag and delivers a 200 Gr FTX at 2200 FPS.

  • SpartacusKhan

    how does it compare with the .375 socom from Tromix for the AR15, I wonder?

  • mazkact

    Innovation is good for all of us. I thankfully am a stick in the mud, one day I may branch out and try 6.5 Grendel but for now I’ll stick with all of my mostly old tried and true cartridges. Everybody is still chasing 6.5×55 a Nineteenth century design.

  • Oldtrader3

    Why not a 9.3×57 Mauser? You get more case capacity in a factory cartridge case! Over all, I would rather have a 9.3×62 Mauser for many reason over the .308.

    • Xtorin O’hern

      um, because 9.3×57 does not fit in an AR-10

      • Anonymoose

        Perhaps in a BN36, but at that point you may as well go with a .35 Whelen. On a side note, I’d be all over a 7.62x54R AR-style rifle, and maybe if we got one made they might start importing the weird 54R-based rounds like 6.5x54mmR, 9x53mmR, 9.3x54mmR, and 9.5x54mmR (nugget case with .375 boolit). iirc, Barnaul makes a 9x53mmR load specifically advertised for walrus hunting, and the novelty alone makes me want to get a box.

  • Some Rabbit

    40 years ago everyone was necking down cartridges. Now we’re necking them up.

    • iksnilol

      Makes sense, less barrel wear.

      • Anonymoose

        Yeah, we’re shooting our guns a lot more than the average fudd 50 years ago with his .243 or .270 that he only shot maybe once a year.

  • Sledgecrowbar

    I’m not sure I’d recommend this round for all North American game. Being a heavy bullet for the cartridge capacity, it would be good at limited range, but I wouldn’t choose this for a hunting expedition over a cartridge with more powder under the same bullet. The advantage is having 20 rounds semiauto, which sounds nice for people who aren’t necessarily hunting but find themselves in bear country and don’t have a thousand yards of visibility on all sides, but I would choose a round that can be expected to humanely take the largest game at farther range if I get to pick.

  • Daniel Woods

    Didnt someone do this like two years ago with the 375 reaper?

    • Giolli Joker

      My initial thought, then I realized that one was sized to fit Ar15 magazines, this is a bigger round that fits .308 length chambers.

  • Joe Met

    “the release of his latest caliber” It is not a caliber, It is a cartridge.

  • Larry

    Since I am a sucker for 375s I will be looking close at this round.

  • Richard Lutz

    Parent .308W is all you need

    Pray tell what is wrong with the parent .308W round which is clearly more feed reliable? It is supremely versatile with a huge range of factory loads and countless .30 caliber bullets that can be loaded into it. It can be used on rabbits and anything up to elephants when loaded with 220-grain round nosed solids that will reliably penetrate an elephant’s skull. How many people can shoot anything much more powerful than a .308W without developing a flinch? The 9.3x62mm has too much recoil for me, much less a .458WM.

    The only other round worth considering for general purpose use is the 7.62x54R round that is better for single shot and double barrel rifles on account of its rim. I prefer the 7.62x54R round as it has near identical ballistics to .308W round and is chambered for the most rugged and reliable bolt action rifle ever made, the Mosin-Nagant. The overrated Mauser 98 is nicer in some ways (and prettier) but falls on its face in the areas that really count, as we saw in Russia during WW2 where the Mosin was clearly superior, due to the Mauser’s closer tolerances and its stoppage prone double-column magazine.

  • jonp

    I’m all for new cartridges but why do I want this over my 35 Whelen?