.458 SOCOM build questions...

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Sgt_Jamez

Sergeant
Full Member
Minuteman
Dec 24, 2009
265
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Carmichael, CA
#1
Howdy boys... I'm tinkering with the idea of converting one of my 5.56mm uppers to .458 SOCOM, but I have a few questions before I start heating up my bank account.

#1 - Can I use a standard 5.56mm AR upper? Does the ejection port need to be altered or any other mods to the upper?

#2 - Anyone here have any experience with the MGI 16" heavy bbl?

#3 - The MGI bbl has an 11/16x24 thread, can anyone recommend a good brake for this?

Would anyone care to share their lessons learned for building a .458 SOCOM?
 
#2
Re: .458 SOCOM build questions...

I have one, the ejection port is larger than standard.
My only advice is, pay attention to eye relief when choosing your optics. Do Not try nose on the charging handle and butstock half above your shoulder loosly like a 223... Trust me...

It is low pressure,so if suppressed SBR is in the future get carbine length gas system.

458 SOCOM is Shock and Awe with 300gr Barnes.
 
#3
Re: .458 SOCOM build questions...

I bought the complete upper from RR and used a RR lower that I already had. These things are awesome to shoot and I put a MK4 2.5-10 on it to see how well it would group...it was supprising well. 10 shots at 100yards with 300grain TTSX. One ragged hole just under the size of a half dollar. I'm sure with some work it would be better. At 300 yards it still grouped very well. Should take care of any deere that attack!!!
 
#5
Re: .458 SOCOM build questions...

I've posted this pic like 3 times over the years. It's a .458 SOCOM built entirely by RRA(with the exception of the DD rail). If you don't extend the stock fully, your Badger Tac Latch becomes a Badger "Tap" latch as it will tap your nose!
eek.gif

.458 SOCOM is a hell of a round! Brass is high dollar though. Not sure if 458socomforums.com is still up and running but that's where I learned the ins and outs of this caliber.

IMG_5964.jpg


I waited for a year and a half on this rifle. The lower is marked .458 SOCOM.
 
#6
Re: .458 SOCOM build questions...

the 458 socom forum got nuked with russian porn spam but they are about to get it back up and going. yes you will have to enlarge your ejection port but other than that all is good .

this is my favorite rifle its a rra upper on an essential arms lower with rra lower parts kit .


DSC_0056.jpg



I done this at 275 yds with hornady 325 grn ftx bullets over a healthy dose of lil gun. the flyer doesnt reflect the rifles accuracy . it reflects me being an elmer fud and jerking the trigger instead of squeezing.

IMG_0676.jpg
 
#7
Re: .458 SOCOM build questions...

A great source for parts, info or built uppers or complete guns is SSK. You can contact them at:

www.sskindustries.com

It takes 6 to 8 weeks to get uppers from them, but every upper is custom built by JD Jones to your specs. What you end up with is worth every penny.

The 458 Socom is a real fire and brimstone round.
 
#8
Re: .458 SOCOM build questions...

I plan on getting an RRA 458 upper some time in the near future. It's got about 4 projects in front of it, but frankly it's only a matter of time before I try it out. I'd save yourself the trouble and just get an RRA upper.
 
#10
Re: .458 SOCOM build questions...

Hey guys. I'm not sure if any of you were on the 458socom forum site that is no longer... but we're trying to put together another one, as many people found it extremely helpful.

The website is www.the458socom.com

It's a small site right now (typical VB forum), with just basic information and some load data. We'd like to try and build it up simular as Marty's was.

Thanks again

Tony
 
#12
Re: .458 SOCOM build questions...

Gas block is .936 dia.
I use a standard carbine buffer and spring. RRA provides heavier springs for carbine and rifle length buffer tubes, but they are not necessary. The cartridge was designed to function in a carbine length system. I do not believe the Enidine is a ncessary investment, but I have no experience with one so I couldn't comment on its effectiveness.

The de facto source for .458 SOCOM information is www.teppojutsu.com. Marty Ter Weeme is the designer of the cartridge and builds .458 uppers when he can. RRA is licensed to manufactuer the .458S but Marty's company Teppo Jutsu and Tony Rumore's Tromix are the originators.
 
#13
Re: .458 SOCOM build questions...

Would there be any advantage or disadvantage to going with the midlength over the carbine length?

Thanks for the gas block info. I have a Troy TRX Extreme forend I want to use with this build, and it will certainly extend beyond the carbine gas block placement.
 
#14
Re: .458 SOCOM build questions...

Carbine is the way to go. Midlength is giving you more dwell time and as mentioned, the .458S is a low-pressure round with a fairly large bore and while it may aid in smoother cycling, the more likely scenario is increased feeding issues...if you were to run a suppressor it might exasperate the issue further.
 
#17
Re: .458 SOCOM build questions...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: CAT5</div><div class="ubbcode-body">
458 SOCOM is Shock and Awe with 300gr Barnes.
</div></div>

You don't say
wink.gif

458barnes1.jpg

or did you mean these?
grin.gif

BarnesTACX3.jpg



<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Sgt_Jamez</div><div class="ubbcode-body">I am guessing most .458 shooters are handloaders as well. What ammo boxes are you guys using? MTMs? </div></div>

I like these MTM's <span style="font-weight: bold">RSLD-50</span> They are designed for the short fat rounds like the SOCOM, Beo, WSSM
 
#18
Re: .458 SOCOM build questions...

You know I was going to do the 458, I had a Beowulf. Brass just to hard to get. Finally ended up/w a 450 Bushmaster everything was available, seems like everything is readily available for it. Shooting it on Wed. Not much help with the 458, just some food for thought.
 
#20
Re: .458 SOCOM build questions...

Man you'll love ur build once you're done with it! I just went with a RR upper that I had to wait for about 8 months for but that was a year or so ago. I also went with a low pro gas block and put on a Troy tube aswell and sure is ALOT nicer than the short one that comes with it from factory. Finding a load that shoots is alot easier than few yrs back, you just need to put ur fingers together and search for it. Although my groups (1-1.5") aren't the best as some that i've heard of it did have good numbers. Barnes 300 TTSX's with a pinch (33.4 grs) of Lil Gun gives me 1991 fps avr., 5 sd and 16 es from my factory 16"er. The round was designed for short barrels. You MAY get a few extra feet faster goin with 20" but with what you're dealing with you won't see much difference.
458socom.jpg

I have since removed the 3.5x10 and replaced it with a 2.5x8 vx3 with M1 knobs and will say that deer seasons are nicer knowing that if conditions are right and I do my part, anything within say 300-400 yds are gona be on da grill
grin.gif
 
#21
Re: .458 SOCOM build questions...

Yeah! Nice looking stick! Is that the 13" Troy? The one I have to use is a 9". I am looking to use the Leatherwood 1-4x 24MM optic. Have you had the stuck case issues I keep reading about? I use the Hornady One Shot.
 
#22
Re: .458 SOCOM build questions...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Sgt_Jamez</div><div class="ubbcode-body">Yeah! Nice looking stick! Is that the 13" Troy? The one I have to use is a 9". I am looking to use the Leatherwood 1-4x 24MM optic. Have you had the stuck case issues I keep reading about? I use the Hornady One Shot. </div></div>

Ya, it's their 11 or 13 one I think idk can't remember. Don't know much about Leatherwood but MAKE SURE it can withstand a beating that the 458 will dish out. My loads, although their on the warm side, hit's harder than any slug gun or rifle that i've ever shot. Few months ago I was able to squeeze of a round of a 416 Rigby and to tell you to me there isn't a whole heck of a difference. Stuck cases... no not YET. I run the Redding dies and I lube and use One Shot aswell. Last weekend though 2 out of 5 cases split right on the shoulder and i'm wondering if using to much lube is the cause of it.?. What weight if pills you wantin to run out of it? H110 worked good and that's what i'm usin for my plinkin rounds but Lil Gun gave me the speed that i'm wanting for hunting. One other thing... Lil Gun is a HOT powder and if you run it hard it will tear up you cases! Extration burrs and every once in awhile a bent case head but still workable.
 
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