.458 SOCOM

The rounds development an incorporation into an M-4 framework was “cobbled together” by people who needed a bit more punch than that offered by the 5.56mm round. It single stacks into an existing magazine.

Are you .458 (11.63×40 mm) shooters bothered by the smaller magazine capacity or is the trade off worth it?

The .458 SOCOM can be loaded subsonic – thus they can be silenced without a big sacrifice.


The ballistics of a 45/70 Government in a semi auto – AR platform (upper).

Do you like the .458 SOCOM better than the .450 Bushmaster?


  1. I’ve never tried the .450 Bushmaster, though a shooter at the range let me try his .458 SOCOM. I found it quite manageable. I should probably assemble an upper in that caliber.

    • There’s the .458 SOCOM, the .357 SOCOM, the .300 Blackout and the .450 Bushmaster, all of which are generally good subsonic rounds. The .458 SOCOM doesn’t perform well at longer ranges, but it wasn’t designed to. It tosses a big round out to punch through a windshield or through an inner city person in Somalia – or wherever and stop them if they’re loaded on Khat or fentanyl or whatever. The 5.56mm might be giving them lethal wounds, but they don’t know it yet.

      I don’t have a .458 SOCOM, but was wondering whether you or anyone else had tinkered with the ammo, etc. Some .458 cartridges don’t cycle as well with CERTAIN uppers as others do, etc.

      • I have a .300 Blackout that I put together on the cheap. I had an stripped upper and some other parts laying around and found a cheap pistol length barrel on sale so I don’t have much invested in it. I haven’t played with it much but so far it seems to work okay.
        I don’t know much about the .375 SOCOM though I understand the case is a necked down .458.
        I’ll have to look into accumulating parts for a .458. While not mandatory, a proper upper receiver is HIGHLY recommended. Anderson makes one that’s not too pricey which is important to me since I have only so many funds I can allocate. I’ll have to look into barrels.

  2. I put together a .450 Bushmaster. It shoots well. It does have a little more recoil than the 5.56. I have not tried it past 100 yards yet.

    • I’ve been told that it reaches out to general hunting ranges – 100-250 yards, but drops off. One would expect it to.

  3. .458 SOCOM is a bottlenecked cartridge that headspaces on the case. .50 Beowulf and .450 Bushmaster headspace on the case mouth. With the SOCOM, you do not have to watch the case length as closely as the straight-walled cases. Easier to load.

    • That’s an important point to a lot of us. I’m just getting started reloading. I should’ve stocked up on primers first, I’m thinking now, then powder and bullets. Then reloading equipment. Ah, well.
      .458 SOCOM would surely put feral pigs flat with a well-placed shot. 10 rounds wouldn’t bother me too much, though I’m a little surprised no one’s done a fat double-stack below the magazine well that brings it up to 16 rounds or more (spitballing here). Or is that because that mag well makes it too hard to do?

  4. I have not shot a 450 Bushmaster but very much like my .458 SOCOM. Not all 5.56 magazines will work for .458 without some modification. For instance you have to remove the stiffening rib (at least that is what I think that ridge in the middle is for) from a PMAG.
    I really like that you can not chamber a .458 round in a 5.56 barreled rifle which eliminates one of my major concerns with 300 Blackout. I could see the potential for me getting confused in a high stress situation and pulling the trigger on a 5.56 with a 300 Blackout in the chamber. Any number of YouYube videos of folks who have done that.
    It does hit really hard, doesn’t recoil all that bad, and is very accurate out to 100 yds. (I haven’t shot it any farther than that so no personal experience. It is expensive to buy but not too expensive to reload with hard cast so reloading dies are on my wish list.

    • Thank you, Ed. I don’t have dyes for it, but if I buy a rifle chambered to .458 SOCOM, I would also need to buy dyes. The chamber pressure shouldn’t be horrible. I presume that you do a full length resize and not just a neck? Or does fireforming the the cartridge handle all but the neck?

  5. I’m only here because LSP told me to 😉

    The .458 is an anti-material cartridge, and the sub-sonic is absolutely devastating against personnel at relatively close (urban) ranges, but it’s not a replacement for 5.56, nor was it ever intended as such.

    I’ve used the 6.8 Remington your lot has apparently settled on, but prefer the .300 blackout/Whisper. Better ballistics and standard capacity.

    The thing that ‘irks’ me though is that … remember the Enfield EM-2? It was adopted By The UK (and almost everyone, Canada, NZ, Australia was going to follow suit) with the .280 cartridge in 1951 (withdrawn because … er you, demanded the 7.62. Then when everybody had been forced to accept that … you dropped it and adopted 5.56).

    So? For at least the last twenty years you’ve been searching for an alternative cartridge that … still doesn’t equal the ballistics of the .280. What’s with that? (Not invented here syndrome?)

    • LSP should stop kidnapping people and forcing them to comment here.

      This blog is diverse. Claudio comments from Italy, John D. from Norway, etc. Lurkers from China and Russia (hi guys) who don’t comment.

      The 7.62 was not dropped (as I suspect that you know), but it’s true that the US went heavy to 5.56. The 7.62 was NOT the ideal cartridge, but politics at the Office, Chief of Ordnance – pushed hard by interests in Big Army went that way three generations ago.

      Subsonic rounds have considerable value, but not as a main battle cartridge (IMHO). The .458 SOCOM at optimal ranges is a good choice, I think. For the close in tool that it is, and with penetration where it is needed in cities, at street corner ranges.

      The search for the ideal cartridge is futile. Ballistics between .257 and .280 will be the best when fired from the right rifle with the right barrel. Is that the best battle option? It’s argued endlessly. Weight per round, weight of rifle, penetration, who is shooting it? The 7.62X39 in inshallah mode or a sniper, and at what range? 0-100M in a city for a rifleman is typical, but in a more open environment, you need to kick that out. The .257 will give you solid subminute of angle depending on the shooter and the rifle, but so will the .280. Are you shooting ball ammo or Sierra Match King or Nossler? Anyway, people will haggle it long after LSP and I are gone.

      • But I so enjoy ‘how long is a piece of string’ argue… I mean discussions.

        It’s much the same as the camouflage pattern debate (how vituprative that argument gets puts calibre and Glock vs. … anybody discussions to shame). As there ‘the best is the enemy of good enough’, what works best in one terrain is the same as wearing a German techno day-glo outfit in another (or weather, or season, or urban vs. rural) and what works in civilian circumstances (and I’m really not jealous of all of you … much) wont work as generalised, all theatre military weapon/cartridge. [I know trying to teach granny again]

        Within my former er … speciality we used subsonic quite a bit (.300 usually in a C7 and .45 in the subguns/pistols). But .338, 5.56 and 9 seem to do the job sufficiently well, depending on range, from my experience (in other words I don’t really have any preference, I just like stirring the pot).

        Oh, he only (strongly) suggested and I became lost in reading past articles, and just thought I’d say Hi (and do some venting/put my oar in),

          • Ha! Able/Anon — I thought you’d enjoy VM.

            But viz. calibers, I like the .45 (mostly Glock 21 in my case) and “fun gun” with 5.56 ARs. 30-06 or 7.62 otherwise, apart from eccentric .303. Saying that, nothing wrong with a .22/.17 plinkabout, imo. Shotguns? Lately it’s been 20s, lighter than a 12, gets the job done against skeet/clays (my usual targets) and doesn’t smash up the shoulder. So.

            But what about the 6s? My UK shooting pals scorn me for not having a 6.8 upper… hmmm. OK, I’ll take the rebuke.

            .280? Nice call, not that I’m some kind of expert.

            LL, I apologize for kidnapping.

  6. PS. Able — I remember my first time firing an SLR on the 30m range at Sandhurst. Remarkably easy and somehow “plasticy” after the wood and steel of the Lees I’d been shooting up till then. I told the overseeing Sergeant that. He looked at me nonplussed, but I was in the “x ring”, so.

    PPS. people used to fire .220s/.217s against turkey here. I was surprised by that, always thought it was a shotgun thing, ‘parently not.

  7. Larry
    I haven’t reloaded any .458 yet; still have to buy the dies. My comment about the cost was about a friends experience. Talking to people who have reloaded though you need to resize the entire case if you want the cartridge to work in any .458 chamber. If you are just reloading for yourself then just resizing the neck is fine. I got my upper from Tromix Lead Delivery Systems https://tromix.com/ because I thought that the guy that helped make the first rifles in that caliber would know what he was doing. Well that and when I called he picked up the phone and was willing to answer all my dumb questions. Totally satisfied with the company and the caliber.

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