Hi All,

I have several LMT complete lower receivers (including MARS) that I'm looking to do something with.  I thought I might build (assemble / attach upper to lower) a 458 SOCOM given Underwood's Xtreme Hunter offering - a really intriguing round.  I thought it might be fantastic for a HD rifle at short distances.

Question:  Who makes the best no compromise / no holds barred, 458 SOCOM upper?  I'm looking for the equivalent of something KAC might produce if they were in this game.  If no good answer, should I build myself from high-end components?

Thanks for your time, thanks for reading, and as always, thanks for your input.

Radio_Silence

Tromix

FPNI.

Tromix.......accept no substitutes

There are several companies that make good .458 SOCOM barrels.  TROMIX, Rock River Arms, SBR, and SSK.  Of those, Rock River and TROMIX have the best delivery time lines and price.  Of any of them, TROMIX has the best quality, quality control, customer service, and know-how about how to properly make and assemble .458 SOCOMs.  There is a lot more to it than screwing on a barrel extension, reaming it out, chambering the barrel, and enlarging the bolt face.  The barrel extension needs to be properly made, the extractor needs to be properly modified or in TROMIX's case, specially made, and the ejector needs to be properly modified, along with the bolt face being opened up.

When you consider cost, quality, experience, rapid delivery, quality control, customer service, and value for the dollar and product selection, there really is only one choice:  TROMIX.

Yes, you can buy cheaper butcher jobs where the barrel extensions are ground down by a monkey with a Dremel and the bolt face gets hit with a cutter but the extractor and ejector sees little if any modification, and you can get yourself a rifle that gives you nothing but trouble with dubious accuracy when it does work, or spend a little more on a TROMIX and get a top of the line product built by a man who has been building .458 SOCOMs from the beginning.  You can get the .458 by the man who actually made the .458 work with the AR platform from the get-go and helped T.J. develop the round, by a guy who has built more big bore ARs than all others combined, and who has more knowledge about what it takes to make an accurate and properly functioning big bore AR than just about anyone else in the world.

IMO the choice is obvious.

Thanks everyone for the advice.

Looks like Tromix is the only serious way to go.  I should have known this as I had Tony rework a Saiga-12 for me years ago.  It is awesome.  So, I'm sure his 458 uppers are fantastic as well.

Question:  What barrel steel should I go with?  It will be 16.25" in length as I don't feel like waiting a year for paperwork to clear.  I'm currently in that hell with a few other items and it's just painful.  My debate is do I go with 416 Stainless or 4150 Carbon?  In 556, I would typically go with SS for additional accuracy, but I don't know how that plays out with 458 (accuracy vs. barrel longevity).  Does anyone have any thoughts on this choice or pros / cons of each?  Any additional advice is appreciated.

Also, I will call Tromix tomorrow to discuss all the options but I definitely want the best upper I can get.  I'm a big believer in "buy once, cry once."

I think you guys have me on the right track and it is much appreciated.

Thanks again for reading and for your input.

Radio_Silence

there is always the ar-pistol sba-3 or 4 if you want less than 16" or a 14.5 w/pinned muzzle device

Ss or CroMo, your pick.  I like SS better because of better rust prevention but that’s the only reason.  You’ll never wear out a .458 SOCOM barrel from shooting unless you have full auto and bottomless pockets, even if you reload.  I have both and I can tell no difference between them.

Form 1 for sbr lower are right at 30 days for approval. I have a 10.5in and 14in tromix black barreled uppers.