458 SOCOM Build List w/ Tromix Barrel


By: Cary Kieffer

This is a brief look at a 458 SOCOM I built for myself. I love the thing, took me 2 years to complete because it kept getting backburner’d by other projects. Anyway, it’s done, runs like a Swiss watch, hits like a tank and is very accurate.

12 inch Pistol 458 SOCOM. I’ll be updating with more pics soon.

The Lower: I could have done this quite a bit cheaper but I wanted it to stand out, it does. A “Jack” skull lower receiver. I had the weapon cerakoted the first time by Keebler Rockwell from Warlock Customs. He did a fine job, he’s great, but I decided on a color change. The thing was titanium and I switched it up to a darker Tungsten I am much happier with the shade. Second go around was by Chris at Backwoods Customs Coatings in New Jersey. Chris turned everything the darker grey and did some highlighting on the skull with some darker tones. I really like his work. He has 6 more of my jobs as I type this. So much more to come on Chris. He can be reached on Facebook or a simple google search. His number is (732) 344-0702.

RRA Star safety which work great, easy to find/feel even with gloves. Seekins Precision enhanced bolt catch and the Hyperfire trigger bow.

Back to the lower. I built it as a pistol. When building for myself I have some stuff that’s just automatic. Rock River pins, buffer, springs and small parts, Seekins Precision bolt catch, Rock River Star safety and KAK Shockwave pistol blades. So those are all in there, I feel they represent some of the “best for your money” parts. The triggers vary for me but this one is a Hyperfire EDT 3. It has the bowed trigger and breaks nicely. They are sturdy and have a good solid primer strike. Obviously the Magpul MOE+ rubber pistol grip. That pretty much sums up the lower. No need for any special stuff, the SOCOM is supposed to run on a regular AR lower.

Timber Creek tanker style brake. The thing looks great and does it’s job. As far as brakes go it’s a bargain at $57. Contact the seller “pdarchery1” on ebay. Guys name is Pat and he has some great prices on these really nice brakes. All sorts of sizes too.

Custom dust cover and a close up of the skull

The Upper: I had my man James Garrison, from Johnsons Sporting goods in Adrian MI, just open up a regular Anderson upper to 458 size ejection port. He is a great Smith and all is well. Of course about 6 seconds after I bought an upper and then paid James, RTB had a sale on Aero Precision 458 uppers. Figures, anyway I bought a couple because once you have a SOCOM, you want another one. At least I do. So with my upper I bought an RTB nitride .875 gas block and pistol length gas tube. I used a TacFire 10 inch rail. These are Chinese but I’ve used 3 dozen of them and they are solid as a rock. Steel barrel nut, clamp on, good finish. There is just no reason to pay more. I love the things.

Off brand BCM style handle and a forward assist cover.

Now the heart of the gun. The 12 inch Tromix barrel. That baby just glows with quality. Everything was perfect. Feed, function and looks, the Tromix barrels are really nice. They come with a matched bolt and all you need then is a carrier and the firing pin, cam pin and firing pin retaining pin. What I did was just take a Toolcraft BCG (nitride) and swap out the bolts. Perfect fit. I finished off the gun with  Timber Creek tanker style muzzle brake and a thread adapter I got off ebay for $15. Last but not least a BCM style charging handle and a Aimpoint Pro. Unless I forgot something that’s the whole gun. I have been using regular old USGI aluminum mags. They work fine but I did want to get a Lancer and try that. For aesthetics only, the GI mags don’t really match the color, a nice black polymer mag would look better.

Chris at Backwoods Custom Coatings does a nice job, get with him at the number above or FaceBook, prices are great too.

Like I said it’s been running like a Swiss watch. No failures of any kind in the first 350’ish rounds downrange. I’ve hand loaded every single round. I mainly shoot 405 grain Missouri HCFP’s but have messed around a little bit with 300 Noslers. After running several loads past the chrono I found out the opposite of what I had guessed would happen. the 405’s were faster than expected and the 300’s were slower. I’m using Starline cases, CCI Magnum Large Pistol primers and H110 for powder. (you get a huge fire ball 🙂 My plinking round is 31.5 grains under the 405. That’ll get you 1582 fps. I ran them up to 35.2 grain of H110, no signs of pressure in the primers, that got me well into the 1730 fps range. I don’t make a regular habit of shooting these but I didn’t see any reason you couldn’t. Just to go out and whack steel, 31.5 is plenty enough ass for that and it’s less beating on your weapon. When I go back north to bear country on quads trail riding, the hotter ones will be in the weapon. That load has every bit of the power my 500 Smith Magnum has. So it’s a beast stopper.

Lee taper crimp and expander die you’ll want to add to your die set.

A little more on reloading get yourself a taper crimp die. Make sure you give it a pretty good crimp. I believe mine is a Lee. Oh and I bought an expander die too. Back to those Nosler 300’s. H110 isn’t moving them out that fast. I’m going to try some Reloader 7 and get back to you on those.

That’s alot of thump!!

Accuracy: VERY. I ran over my glasses with my jeep and I still can get a small cluster at the 75 yards I sighted it in at. When I get a chance I’ll post a target picture with exact numbers on it. I used a 3x magnifier behind the Aimport just to dial it in and then removed it. You shouldn’t have any problem whacking steel out to 200, I can. It took just a short time to learn how much to hold over the red dot Aimpoint. I ordered a clone Eotech, just for S&G, just to see how long it will last with 458 SOCOM pistol recoil. For 33$ what the hell, ya know? You never know it could last forever like this Barska scope I bought eons ago when I was young and broke. $62 and the thing worked perfectly for eons, never did break that I know of, I sold it.

Summary: 458 SOCOM is just raw power…its a ton of fun to shoot. Do I need it? Probably not but who cares. If you can swing one I suggest you do.  It’s accurate, very powerful and if you follow this build list, at least the Tromix barrel, bolt and a good trigger, I can’t see you having bad results. This thing is a beast, I love it. I have an 8 inch going on now. I’ll review that one when it’s done.

The other thing I suggest if you do build/buy one, that you are a reloader. At $2-$3 a round for store bought ammo that can get pricey. If you reload, yes you’ll have the expense of brass up front at roughly 80 cents a case but after that 405’s are right around .30 cents a piece and you don’t spend much on powder/primer when bought in bulk. The Starline brass should last you a good long time of reloading, the 458 SOCOM is a relatively low pressure cartridge at 35000 psi. I have a batch of cases with 4 loads on them now and they haven’t even needed trimmed. They look just fine. I don’t know a case’s end life yet but if I had to guess…I’ll get at least a dozen times per case and maybe more.

The 8 inch I have going now. It’s 22 inches long with SBS collapsible wrist brace closed. It will gain a couple inches after the brake goes on.

The Jack lower and barrel were gifts from my loving GF Kelly. Last X-mas and the one before. She also bought me a USMC 1903A3 WW2 sniper rifle and an original 1884 Springfield Trapdoor 45/70. I shoot them both regularly. Thanks Love, you’re the best. Thanks for reading and train often.

The top two are gifts from Kelly. A gorgeous 1884 Springfield this last Christmas and right below the arsenal refurbished 03A3 with a reproduction USMC scope she got me the Christmas before.. I hit plenty of times from the 600 yard line with it. The middle rifle going down is a 1943 Springfield M1, 1938 K98 Mauser and bottom is a 1943 Postal Meter M1 Carbine

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Cary Kieffer

USMC Infantry/Combat Veteran - Med Retired LEO/8yrs.

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3 Responses to 458 SOCOM Build List w/ Tromix Barrel

  1. Psitampsi says:

    Bert Davis says:, thanks! And thanks for sharing your great posts every week!

  2. Bert Davis says:

    Wow, that is a really wicked cool build.
    And – you must have one helluva girl….

  3. […] post 458 SOCOM Build List w/ Tromix Barrel appeared first on Gun Reviews | Tactical Gun […]

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