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CMMG Chambers Mk4 DTR2 Rifle in 224 Valkyrie the headline at proclaims. The press release below explains the freshly minted caliber’s advantage: it’s “an incredibly flat-shooting round achieving supersonic velocities out to 1,300 yards” out of an AR-15-sized round. Do you own or would you consider . . .

an AR in a caliber other than .223, 5.56 or 7.62? A bolt action rifle in some non-mainstream caliber? A handgun chambered in .327 Federal Magnum, 5.7mm or something other than the usual suspects?

CMMG Mk4 DTR2 in 224 Valkyrie

Boonville, MO –-( Known for delivering innovative, practical products to market, CMMG continues to live up to its reputation with the release of the new Mk4 DTR2 rifle, chambered in Federal Premium 224 Valkyrie (courtesy

Federal Premium introduced the 224 Valkyrie cartridge in December 2017. Its purpose is to deliver exceptional long-range performance that is comparable to 6.5 Creedmoor, but out of a smaller, AR15-sized caliber. The 224 Valkyrie is designed to be an incredibly flat-shooting round by achieving supersonic velocities out to 1,300 yards. With the added benefits of minimal recoil and an affordable price point, 224 Valkyrie has the potential to be the go-to cartridge of long-range shooters for years to come.

Recognizing this potential, CMMG’s engineers quickly went to work developing a rifle that would maximize the effectiveness of the 224 Valkyrie and meet the needs of long-range shooters straight out of the box. The result is the Mk4 DTR2.Federal Premium’s 224 Valkyrie takes the long-range precision and ballistic performance of the MSR 15 platform to unheard of heights.

The Mk4 DTR2 has all of the fundamental features expected in a long-range AR15, including:

  • A 24-inch medium taper barrel, with a 1:7 twist
  • CMMG’s SV Brake to reduce muzzle rise
  • Magpul MOE Pistol Grip and PRS Stock
  • Geissele SSA 2-Stage Trigger

Additionally, CMMG has outfitted this new rifle with an RML14 M-LOK hand guard and all-new CMMG Ambi Charging Handle. The Mk4 DTR2 is built on a 7075-T6 AL lower receiver and a forged 7075-T6 AL upper receiver for optimum durability. It ships standard with a 10-round 6.8 SPC magazine and is backed by CMMG’s Lifetime Guarantee. CMMG also offers five different Cerakote colors as an optional upgrade.

Mk4 DTR2 in 224 Valkyrie:

  • PART#: 25AB216
  • BARREL: 24″ MT 416SS, 224 Valkyrie, SBN
  • MUZZLE: SV Brake, Threaded ½-28
  • FURNITURE: Magpul MOE Pistol Grip and PRS Stock, Ambi Selector, Ambi Charging Handle
  • RECEIVERS: 7075-T6 AL Lower, Forged 7075-T6 AL Upper
  • TRIGGER: Geissele SSA
  • MAGAZINE: 10 Round 6.8 Magazine
  • WEIGHT: 9.2lbs (UNLOADED)
  • LENGTH: 44.5 inches
  • MSRP: $1,699.95

Upper Group, Mk4 DTR, .224 Valkyrie:

  • Part#: 25BB257
  • MSRP: $899.95

Lower Group, Mk4, w/PRS Rifle Stock, SSA, Ambi Safety:

  • Part#: 55CA37F
  • MSRP: $749.95

Bolt Carrier Group, .224 Valkyrie

  • Part#: 25BA49E
  • MSRP: $174.95

Barrel Sub-Assm, 24.0″ MT 416SS, 224 Valkyrie, SBN

  • Part#: 25DB20C
  • MSRP: $259.95

CMMG Lifetime Quality Guarantee

CMMG, Inc. will guarantee its products against defects in material or workmanship. CMMG, Inc. will repair, replace or substitute part(s) (at CMMG, Inc. discretion) at no charge to the customer if a defect of material or workmanship is found. All service work must be carried out by CMMG, Inc.

About CMMG:

CMMG began in central Missouri in 2002 and quickly developed into a full-time business because of its group of knowledgeable and passionate firearms enthusiasts committed to quality and service. Its reputation was built on attention to detail, cutting edge innovation and the superior craftsmanship that comes from sourcing all their own parts. By offering high quality AR rifles, parts and accessories, CMMG’s commitment to top-quality products and professional service is as deep today as it was when it began.


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  1. Nope. I have the usual suspects, 5.56/.223, 9×19, .40, 12 ga, .22, .380 ACP and 7.62x54r.

    I can’t really afford to invest in an obscure or more expensive caliber at this point. Of the above, I shoot .40 the most frequently since I am a Firearms Instructor I get to use it for free, after that it’s 9 and .223.

  2. My main hunting rifle is a 35 Whelen custom built on a Remington 700 action. Also, an old Remington Mohawk 600 chambered in 6mm Remington is a favorite deer rifle.

      • My rhetorical question was in response to “Do you own or would you consider . . .
        an AR in a caliber other than .223, 5.56 or 7.62?”

        But hey Geoff, keep up the reading. Your comprehension should get better over time.

        • How was he to know that? You could have been responding to the original question of “Do you own an obscure caliber?” And considering he put part of the question into his response maybe you should be the one checking your reading comprehension.

          Or just don’t be a prick and let him know you were responding to the AR question then let it go from there, that’d be cool too.

  3. Most of my obscure calibers are essentially mil-surp rounds.

    I’m sure a decent number of people have 8mm Mauser and .303 British in their inventory.

    Good luck finding a lot of people like me with a stash of 6.5x50R Japanese and 7.7×58 Japanese though.

    • One of my LGS’s just got in a bunch of Mausers, and also a fairly good condition 7.7mm Arisaka. Its pretty tempting, I’d have no issue reloading it, but Ive heard the brass itself can be pretty hard to find.

      • 7.7 brass is pretty expensive, and difficult to find, though some people make it by cutting down and fire forming 30-06 brass. I bought some brass from Norma, I think through Midway USA, and just keep reloading the same few cases since I don’t shoot that rifle often.

    • 9×18 mak is as obscure as I’ve got.
      22, .380, 9×19, .38, .357, 12 gauge, 5.56, 7.62×39, 7.62x54r, and .270
      I like my ammo affordable and available.

    • 8mm Mauser woild be my most obscure caliber in use. But I stockpiled a number of crates of the Turk when available.

      7.62x54r would be the next. I only bought one crate of Albanian and milsurp 54r is getting very scarce in my part of the world.

      .303 is not a problem because I still have lots of recent factory (HXP &PMC), plenty of brass, projectiles, etc, and two No4s converted to use .223.

  4. “… it’s “an incredibly flat-shooting round achieving supersonic velocities out to 1,300 yards” out of an AR-15-sized round.”

    So… the round is the size of an AR… naval artillery is the topic here?

    In all seriousness, 5.7 is a good round. Other than that you’re gonna have to define “obscure”. Like old milsurp or what?

    • My old Karl-Gerät (small bore version) fired rounds that big and never got near the ocean. Wasn’t supersonic though. I was always embarrassed about that.

    • Count me as well for 6.5 mm Jap!

      That caliber is so unusual that I NEVER seem to be able to find ammunition, even over the Internet.

    • I’ve got a 7.5×53.5 Swiss for the 1889 Schmidt Rubin. I cast a long 230gr .308 projectile for it, in a Swiss 7.5×55 berdan primed case.

      I’ve got some 7.62 Spanish Mausers. Again, I cast and powder coat or enamel coat 180gr for it. FMJ 308win or 7.62 NATO are just a bit too hot for a continuous steady diet for it.

      I’ve got a 6.5 Swedish. I cast and coat for it. Use blank wood ammo that I got for it dirt cheap. I pull the bullets, dump the powder, and keep the primer installed. Works well (and super cheap) for me.

      I also reload 7.5×55 Swiss Berdan brass with russian metric primers for the k11/G11/K31.

      So, I’ve got a few oddities.

    • I bought an FN Five Seven (5.7mm) before the holidays and my wife adores shooting it. It is now her home defense gun of choice.

      • Yet the only one I have that I can’t get am mo for at Walmart.

        The more obscure part is that it’s in a ri fle manufactured in 2010.

        • It’s just *somewhat* obscure in America. Obscure probably isn’t even an accurate term, just not as common as other rounds. .303 is to many countries what the 30-06 is to us.

        • Fortunately, thanks to all those Lee-Enfields still in common use out there, I can buy all the cheap Serbian am mo I’d like.

  5. I still have the first centerfire rifle I bought over 40 years ago. A sporterised Type 38 Japanese Arisaka with an intact Imperial Chrysanthemum in a birdseye maple stock (probably done in the late 50s or early 60s) and rechambered for 6.5×55. A great deer rifle in my teens, but hard to find ammo for it then.

    • Beat me to it… outside of that I have some Aguila Mini Shells, 22 shorts and 5.7×28. Not exactly obscure.

      30 Carbine too I guess…

  6. I want to make an AR in .25 Remington…an obscure antique caliber that you can still make ammo for from necked down .30 Remington brass. Why? Just because I will have the only one in the World!!!


  7. FN Five Seven in…you guessed it. 5.7
    FN PS 90 in 5.7
    Home built AR in 6.5 grendel
    Desert Eagle in 50AE

    Love my obscure calibers

  8. The most obscure calibers I’ve had would be 6.5×55 Swede or 7.5 Swiss. I have been giving some of CZ’s bolt guns in 6.5 Swede a pretty hard look.

  9. Everything I’ve got now is pretty conventional. One 10mm and one 9x18mm is about the only guns I have that eat something ‘obscure.’ But once upon a time I did have a Nagant revolver in 7.62×38mmR , a Enfield revolver in .38 S&W, CZ-52 in 7.62x25mm, and a Desert Eagle in .41 Magnum.

  10. if it’s still there at tax time, I found a 300 savage in a Japanese rifle with the mauser action, I thought that was pretty obscure.

    • Interesting! Do you know what it was rechambered from?

      My choice for “most obscure” in my collection is what I refer to as the “.318-300 Savage”. It was a beautiful German Mauser (1935-1939 vintage) in given to my grandfather when he was young and dumb (his words!)

      It was originally chambered in 8.15X46 (obscure to start with!) and as far as I can tell, it started life as a sibling to this beauty:

      He proceed to sporterize it (or, “butcher it”, as he said) and had it rechambered in .300 Savage because he needed a deer rifle. But, with a .318 bore, you basically load it with .300 Savage dies and a .318 expander ball. A little excess brass wear, but it works, and I’m running 3″ groups at 100 yards.

      It’s topped with a fixed 4x Lyman scope with a ‘dot’ instead of crosshairs. And, I found out that the ‘dot’ disappears nicely at day break, so you can’t see it when you put it on a deer that’s sneaking through the woods.

      • no clue what original was, it was a college credit for someone locally to modify something that had a bad bore ect. pretty little rifle for sure, I’ll make it better if I get it, needs a stock done, and blueing doesn’t exist on it

  11. 5.7×28 (PS90 and 5.7 pistol), 762 Nagant, 762 Tokarev (PPS43c, tokarevs, cz52), 9×18 (maks and others), 32 acp (original scorpion, vzor 50, 70), 8mm Mauser (k98 polish made no german stamp, vz24, assorted mausers), Desert Eagle 50 AE, 6.5 Jap, 7.7 jap, 9mm Jap revlover, 38 S&w….sorry. I collect stuff. I also keep a minimum of 2500 rounds of each, sealed away in air seal cans.

    • An amazing round, that 32-40. Strong on deer and so much fun besides. I also like the 7-30 Waters but for sheer fun the old .307 and .356 Winchesters rule. Strong older , now pretty obsolete cartridges. Oops I messed up, all my choices were for the lever guns, so sorry black rifle fans. And just to strengthen my point, the old 32-20 in a handgun or rifle is still good medicine

  12. If you had asked this question 3 or 4 years ago, I would have said .22LR, but it seems to have returned from obscurity.

  13. I have an 8mm mauser that I will not buy any ammo for (also it is taken apart, and I’m not very inclined to put it back together) and a .30 Remington, which I have 5 rounds remaining for, but I will buy more ammo for that; it was my great-grandpa’s.

    Other than those, I do not have any unusual calibers, and have decided that, for the forseeable future, I will not acquire any; I want to be able to feed stuff easily. I even sold off my .300 BLK, despite being a fan, because it is just too hard to keep in ammo.

  14. i dont load or reload so i only own firearms chambered in calibers readily available at my local wal mart

    that fact is .22lr .38 .357 9mm .40 .45 .223/5.56 7.62×39 .308 12 gauge will get 98% of people out of 98% of any jams they might ever find themselves in

    i was really hoping the 6.8 spc was going to take off

    when it got down to $10- $12 a box at walmart i was going build an ar in it

    that didnt happen now im waiting for .300 blk to do what 6.8 spc didnt

  15. .44 Automag with lots of brass and reloading dies.
    Ruger, Smith and Wesson and Henry .41 magnums with lots of brass, reloading dies and .41 caliber Corbin bullet swaging dies. 9mm brass, when properly heat treated, makes an excellent bullet jacket for a 210 grain JHP.

  16. Only two rifles .338 Spectre and .243 WSSM ARs. I don’t consider 5.7 or .327 Fed obscure but I have pistols in those calibers. Next AR build might be a .375 Raptor.

  17. I hope to be the owner of a .577 Snider in the near future, so when that happens, I will be an obscure caliber owner.

    There’s just something about 19th Century firearms that appeals to me. I can’t explain it.

    • I have two sniders. Midway USA has the 24 gauge shotgun shells to reload for it, so I would snag a few boxes before they sell out!

  18. No, I don’t buy guns in obscure calibers because the ammo for them is not cheap & plentiful. Ammo price & availability is a serious consideration point for any gun I buy.

  19. .38 super. Accurate, flat shooting, mild recoil (at least in a full size 1911), and ballistics that slightly exceed 9×19 +P+ (though you need to go to the smaller ammo companies for ammo that will do that). Feeds better in a single stack 1911 than 9×19.

  20. 9mm Police in a pistol and 348 Winchester in a rifle. I have things in common calibers already, so am not worried if a few are uncommon.

  21. 7.65 Argentine
    6.5 Creedmore (although I guess that’s a lot more mainstream now than three years ago when I bought it)
    50 Beowulf
    7.7 Jap
    7.62X54 (which isn’t all that odd)
    303 British
    50 BMG

    I’m sure I’m forgetting some stuff.

  22. 7.5 Swiss – not exactly obscure but not a Wally World or even Academy Sports round
    7.62 x 25 pistol – same as above
    .25 acp – getting hard to find as nobody makes these mouse guns any more. I have a set of dies but the round is so tiny that my old arthritic hands can’t handle the bullets or brass. I’ve got an old Beretta 21A that I bought as a hide out gun when I got into law enforcement 27 years ago and its kind of fun to shoot but factory ammo is getting pretty rare.

    • I’ve got a bucket (yes, bucket) of .25 that someone gave me years ago. I’m not likely to shoot that much .25 in my grandchildren’s lifetime. Wait, that may qualify for a ‘horde’ of .25 in slave states 🙂

      Seriously. Random guy at work that I know a bit, just says to me “I’ve got a bunch of .25, you want it?”

      Sure says I.

      Bucket appears a few days later. Thanks random work guy.

  23. 6.5×55
    6mm PPC

    I don’t think the Swede is that odd (maybe not mainstream, but not out there).

    6mm PPC is just a cult 😉

  24. Obscure: 5.7×28, 20 Practical, 300AAC Blackout (though now more widely available), 458 SOCOM

    Less obscure: .22LR, 9×19, .223, .308, 7mm Rem Mag, .45ACP, .380, .357Mag, 7.62×39, 30-06, 300 Win Mag, .17HMR, .22Mag, 20GA, 12GA, .410

  25. Black powder only 45-70. 8mm mauser x9. 9×18 mak.. 348 Winchester x3. 300 blackout. 458 socom. And 50bmg. And would PPU please start making 458 socom so I can afford to shoot it more than 10rds a month? I roll my own but geez it’s still costs to much.

  26. I really like my American 30 from Black Hole Weaponry. Its a 30 cal. based off of the 6.8 SPC case. Bullet weight ranges from 110gr to 150 gr with a sweet spot arounf 125-130gr. Uses 30 Herrett resizing/seater dies. In my 20” barrel i get the 125gr Sierra PH pills around 2630.

    For those that dont reload ammo, its basically a 7.62×39 with an additional 300-400 fps, less drop between 200-500yds and uses any 6.8 ar15 mags and bolt(excluding the special LWRC 6.8 magpul mags). Since it uses 6.8 mags, there are absolutely no feeding issues.

    Another wildcat i recently got into is the 243 LBC from Black Hole Weaponry.

  27. .338 Federal in an AR rifle. After building the rifle, it was difficult to find quality hunting ammo. However, recently Federal decided to manufacture Vital Shok again more than a year they told me they would be manufacturing the bullets.

    .303 in a 1948 Indian made Lee Enfield No.1 Mk III. I paid $62. It was completely covered in cosmoline. I took it to car wash, degreased it, then took it apart and degreased again. I was able to 1/4 silhouette at 200m without adjusting the sights with cheap Pakistani ammo.

  28. 6.5 Grendel. Someone called it a “novelty round” a while ago. Shoots flat and has a good range. My rifle shoots sub-MOA and is more accurate than I am. No one so far has mentioned it so I guess it’s pretty obscure (unless you’re a member of the Serbian Special Brigade).

  29. .416 Ruger… Talk about a niche cartridge… Was designed solely to get .416 Rigby 24” barrel ballistics out of a 20” brush gun barrel.

    At $4+ a round this cartridge never got off the ground… I was rather surprised that I was able to sell the M77 chambered in it with a minimal loss (and a couple of boxes of ammo to sweeten the deal).

  30. Can we please stop referring to 10mm as an “obsolete” cartridge?… Considering that Buffalo Bore, Double Tap, and Underwood Ammo built their companies on hot loadings of this cartridge and that any gun shop worth it’s salt will usually have 2 to 4 different brands in this caliber hardly qualify it as obsolete… Why would Glock still be producing the Glock 20, 29, and 40 and why would we have a new 1911 chambered in 10mm every other month if the cartridge had gone the way of the dodo bird.

  31. Does .257 Wby mag count? It’s not exactly obscure, being a factory round and all, but I see very few around. Plus, Its easier to make your own brass from 7 mag than to find factory ammo or Wby brass in Montana.
    I can get 4000 FPS on a 75 grain projectile. Or use heavyweights for bigger game. I find it to be a quite useful and versatile caliber.

  32. .577-450 Martini in a Cavalry carbine Martini Henry.
    .43 Spanish in a Remington Rolling Block – short barrel Artillery carbine marked with crossed cannon and “República Oriental del Uruguay”.
    .310 Cadet, in a Birmingham Small Arms Martini Cadet made for the Australian Military Cadets. Kangaroo stamped on the top of the receiver. Bought that one in 1970 for $75 at a gun store in Berkeley, Calif, before the state was seized by the commies and turned into the People’s Republic of California. The .310 got me started on reloading – bought a set of RCBS dies that let you reload .32-20 brass (minus 1/4″) into the .310 – it also taught me to slug the barrel for accuracy, since mine turned out to be .318 diameter. The .311 lead bullets I first tried sort of rattled down the bore and were going sideways (keyholing) at 25 yards. Ended up with a bullet mold that poured a .320″, 120 grain bullet (sized down to .318) that is pretty accurate in a 100+ year-old rifle.

    Hey, it keeps me out of bars and houses of ill-repute.

  33. .41AE (Action Express) – fortunately the Jericho 941 by IMI also has a 9MM barrel, so I can still use it. I still have one box of the .41AE left….waiting for the right day to fire the last of it.

    Other than that 30-40 Krag but at least you can still get that.

  34. 6.5 x 53R Dutch / Romanian on a Mannlicher-style (clip-load, not the uber- kewl Greek rotary mag) action.

    .400 “Rook”, on a ‘baby” Snider action.

  35. Not a particularly obscure caliber, but I have a Kimber 17 Mach 2 Conversion kit for my 1911. They can’t have sold too many. I can’t say I’ve ever seen another one.

  36. 7.65×53 Mauser. Mauser’s first smokeless cartridge for the 1889 Belgan rifle.
    The cartridge and 1891 rifle was supposed to be our service rifle instead of the Kraig.
    If that had been the case, there would have been no need for the 30/40, 30/06 or 7.62 NATO.
    Even the 30/30 would have been a .31/30.

  37. 7.62 x 53R Finnish target rifle. Very similar to the much more common 7.62x54R. Lapua makes them and sells them in boxes of 20 for about $65.00.

  38. .22 Harwood Hornet
    .32 Ideal
    .28-30-120 Stevens
    .25-21 Stevens
    All four were commercial offerings. I won’t list the wildcats.


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