Click on a Frequently Question Below to
Link to the Answer.
Who developed the .458 SOCOM? Was it Tromix?
Can I form my own cases? Isn’t it just a necked
What does SOCOM stand for?
Where can I buy an upper?
You mentioned the .50 BeowulfTM. Which is better,
the .458 SOCOM or the .50 BeowulfTM?
What is the best twist rate?
What is the optimum barrel length?
What is the shortest possible barrel?
What type of velocity can I expect?
What type of accuracy can I expect?
What is the maximum range I can use the .458 SOCOM?
What kind of recoil can I expect?
What lower, stock, other parts can I use?
What are the best or preferred optics?
Where can I buy loaded ammo?
Can I shoot subsonic loads?
How loud are the subsonic loads?
What about putting a suppressor on one of these?
Do I need a muzzle brake? Do you offer one? What
about flash hiders?
What about reloading?
I am new to reloading, would this be a good
cartridge to learn on?
Where do I get brass, bullets, etc.?
What is the trim length for the brass?
How do I resize the brass?
What bullets can I use?
What about crimping? Bullet set back?
What primers should I use?
What powders should I use?
Where do I get dies?
Which dies are better, CH or Lee?
Can I load these using a Dillon progressive?
Where can I find load data?
the .458 SOCOM? Was it Tromix?
.458 SOCOM was developed by Marty ter Weeme, founder of
Teppo Jutsu LLC in 2000. The impetus was an informal
("beer and barbeque") discussion with a senior
member of the US special operations community regarding
the apparent lack of effectiveness of the 5.56 x 45
cartridge in recent conflict. In particular, the reports
from members of Task Force Ranger in Mogadishu, Somalia
that multiple shots were required to neutralize members of
the opposing force led to the request to develop a new
cartridge that would deliver far more energy from short
barrels at relatively short distances. After the design
was completed, Tony Rumore of Tromix Corp in Broken Arrow,
OK was contacted to build the first prototype. Based on
the favorable reviews, commercial production was started
and the initial rifles were produced by Tromix. Currently,
several firms offer rifles or upper assemblies in this
caliber, including AR-15s, AK-47s, single shot and bolt
Can I form my
own cases? Isn’t it just a necked .50AE?
could form your own brass; however it would be
economically unwise. The only case that has the proper
base diameter and rim diameter is the .425 Wesley
Richards, which runs about $4 a piece. Any other brass
will not have the proper rim size, either too large or too
small. In a pinch, you could form .458 SOCOM from .50
BeowulfTM but the rim would be smaller. The
initial prototype brass bore the .50AE head stamp and this
has caused some confusion. The SOCOM case is 1.575"
long, the .50AE is 1.290" so therefore, you CANNOT
form the SOCOM case from the AE case.
What does SOCOM
refers to Special Operations COMmand, the joint service
command based in McDill, FL that governs the various
special operations units such as Naval Special Warfare
("SEALs"), Army Special Forces ("Green
Berets") and Air Force Special Operations. The
cartridge was given this name based on the original
impetus from special operations mentioned above as well as
the fact that a similar cartridge saw limited use in
Vietnam with special operations as well.
Where can I buy
the time this FAQ was written, uppers can be purchased
from the following sources:
Jutsu LLC – www.TeppoJutsu.com
Corp – www.tromix.com
River Arms –
– expected 4th quarter 2005
addition, there are a number of other companies that can
supply uppers; however, they use barrels and bolt supplied
by Teppo Jutsu LLC under licensing agreements.
the .50 BeowulfTM. Which is better, the
.458 SOCOM or the .50 BeowulfTM?
is one of those debates that neither side wins. Both
cartridges are very similar, yet they are quite different.
We had access to some of the information on the
predecessor of the .50 BeowulfTM when we
designed the .458 SOCOM. We designed it the way we did for
very specific reasons. I admit I cannot be impartial, but
I will give as honest a comparison of the two as I can:
size – the SOCOM rim is the same as the .308
Winchester (7.62 x 51), the Beowulf rim is the same as
the 7.62 x 39 M43 cartridge used in the AK-47. The B rim
is easier in that you can use existing bolts for the AR.
The S rim is easier in that there are hundreds of
thousands of (old) bolt action rifles that use this same
rim and that could be retrofitted to the SOCOM (all the
old Mauser rifles ….)
length – as mentioned earlier, the B is 4mm
longer than the S. A lot of this extra room is taken up
by the body of the bullet anyway, so it does not gain
you that much.
– the B uses the case mouth, the S the shoulder. There
are those that feel using the shoulder offers inherent
greater accuracy potential, but both rounds are capable
of just about the same accuracy. Both are intended to be
used at the same maximum range as well, so it really
does not matter much.
selection – this is where the S has the B beat,
hands down, due to large variety of .458 bullets
compared to the .500. But with the advent of the .500
S&W, the B is starting to catch up.
– Before Rock River got into the game, the S uppers
were all custom jobs whereas the B uppers were more
"semi-bulk". The S uppers are available in
just about any configuration you can imagine, but that
comes with a price tag. The B uppers come in a certain
number of configurations but with a lower cost and they
might be a little easier to get (again, before Rock
River took up the .458 that is)
– Let’s be honest. The difference between a
.458" bullet and a .500" bullet is a whopping
0.042" or a hair under 3/64". If you hit
anything with either, it will be hurting or dead. That
0.042" won’t matter a bit. Both have just about
the same muzzle velocity so just about the same power.
The B has a little more room for powder and with the
slightly larger diameter bullet will edge out the S. But
the S has bullets with much better BC available so it
should out perform the B at distance.
as you can see, the difference is really not that big. A
lot of it depends on personal preferences, or perhaps what
your budget is or whether you already reload or similar
considerations. You can’t go wrong with either.
What is the best
of the reasons .458 was chosen was to allow the use of the
commercially available heavy bullets (500 and 600 grains).
To stabilize these at subsonic velocities, a relatively
fast twist is needed. If you plan on shooting mostly light
bullets (250-400) you can get away with slightly slower
twist and the slower twist MAY stabilize the 600-grain
bullets but likely won’t. Basic guideline is as follows:
bullets (250-400 grain) – 1 in 18 twist
bullets (500 and 600 grain) – 1 in 14 twist
What is the
optimum barrel length?
cartridge is intended as a short range "brush
buster". As such, we feel the optimal length is about
16", as a compromise between handling and velocity.
Longer barrels will NOT offer substantially more velocity
due to the fact that relatively little powder is available
and relatively fast burning powders are used. As a matter
of fact, the factory loaded 600-grain subsonic load is
designed to achieve complete powder burn in a 9.5"
barrel. Most of the uppers that have been built have
featured 16" barrels, with the second most popular
length being 20", followed by 10.5" for SBRs/pistols.
What is the
shortest possible barrel?
typical short barrel upper will have a 10.5" barrel;
however we have managed to make an upper function with a
7.5" barrel. You can’t go much shorter than that…
What type of
velocity can I expect?
will vary from rifle to rifle and obviously also depend on
the bullet that is being loaded. However, some of the
typical velocities from a 16" barreled upper are as
grain bullet – 1800 to 2000 fps (higher has been
grain bullet – 1600 to 1800 fps
grain bullet – 980 to 1300 fps
grain bullet – 1000 fps
What type of
accuracy can I expect?
with velocity, accuracy will vary from rifle to rifle. The
cartridge, however, is capable of quite respectable
accuracy. With hand loads, low power optics and the
shooter doing his job, groups as low as 0.5" (yes,
true 0.5") have been recorded. We typically tell
folks that 1.0" groups at 100 yards are the norm for
the 300-grain JHP load. The 500-grain subsonic load does
not appear to be as accurate but it was never meant for
ranges beyond maybe 50 yards.
What is the
maximum range I can use the .458 SOCOM?
cartridge was intended for short range work, either in
dense brush or otherwise in urban theaters for LEO/MIL
applications. As such, after 125-150 yards, the bullets
tend to drop off VERY rapidly and we tell folks to
consider it a 100-150 yard cartridge. Accomplished
shooters can shoot the cartridge accurately at much
greater distances, just like the .45-70 was used to
decimate the American bison population at 1000 yards.
What kind of
recoil can I expect?
is subjective, however, most of the folks who have shot it
tend to use the comparison to either a 20- or 12-gauge
shot gun. The 400-grain loads seem to have the most
unpleasant recoil impulse, the 300-grain does not appear
that bad nor does the 500- and 600-grain subsonic load. I
have shot it in a 10.5" SBR on full auto with 300-gr.
JHP loads and found it not that hard to handle. From the
bench my .308 has seemed to kick worse. See the next
section about some pointers.
stock, other parts can I use?
.458 SOCOM was designed to fit any mil-spec lower. Thus,
any of the lowers out there that meet mil-spec should
readily accept the .458. No modifications should be needed
to your lower and no negative effects to the lowers have
been reported. Based on customer reports, the following
aftermarket modifications can help reduce any felt recoil
and make your shooting experience a more enjoyable one:
– the standard A2 stock has a butt plate that becomes
a "meat grinder" with the .458 SOCOM. The most
popular stock tends to be the ACE Ltd Skeleton stock
with the thick rubber recoil pad.
Collapsible/telescoping stocks should be used with
caution; we have received reports of stocks failing and
Spring – While the standard spring will
work, a lot of shooters prefer a spring with higher
spring constant such as the MGI or Wolff
– Again, the standard buffer will work but the MGI
Recoil/Rate Reducing buffer is a popular item among big
bore AR shooters
– the .458 SOCOM was designed to work with any
GI/Mil Spec magazine. We have not heard of any
particular type or brand of magazine that did not
function. Magazine capacities for the different size
magazines are as follows:
rounds of .223 – 3 rounds of .458 SOCOM
rounds of .223 – 7 rounds of .458 SOCOM
rounds of .223 – 10 rounds of .458 SOCOM (have heard
rounds of .223 – 13 rounds of .458 SOCOM (have heard
MWG 90-round .223 drum can hold as many as 33-36 rounds of
.458 SOCOM which makes for some formidable firepower. The
BETA mag WILL NOT WORK with the SOCOM.
What are the
best or preferred optics?
is better, Ford, Chevy or Dodge? Because of the recoil,
the preferred optic will have longer eye relief than
typical. Lower power scopes such as those originally
intended for use with a shotgun are popular, however, the
vast majority of shooters use either the Aim Point or the
EOTech as these seem particularly well suited to the type
of shooting done with the .458 SOCOM.
Where can I buy
now, only CorBon offers loaded ammunition, specifically
the 300-grain Jacketed Hollow Point, the 400-grain Barnes
Round Nose SOLID and the 600-grain Barnes Original
SUBSONIC. We are working with some other companies to get
them to load the cartridge as well.
Can I shoot
this was part of the original design intent, the answer is
a resounding YES. Both the 500- and 600-grain subsonic
load has proven quite popular and will function without
issue through the uppers.
How loud are the
not as loud as the 300-gr high velocity load, they are
still not quiet enough to forego ear protection.
putting a suppressor on one of these?
uppers have been fitted with suppressors, either muzzle
mounted or semi-integral versions. Different brands have
been reported, such as SRT and GemTech, as well as Form 1
versions built by qualified individuals. With the 500- and
600-grain subsonic load they tend to make for a very nice
and relatively quiet package. Suppressing a low pressure
large bore cartridge has its challenges, and Hollywood has
created a false impression of how quiet a suppressed rifle
typically will be. These uppers are not like you see in
the movies and a lot of the noise is from the action
cycling. If you want the ultimate in suppressed .458
SOCOM, the Remington 700 Etronix version with
semi-integral suppressor would have to be it. Other
calibers are far more suited to suppressing but the SOCOM
is no slouch. Remember that the 11.63 x 33 was used in
suppressed bolt guns in Vietnam ….
Do I need a
muzzle brake? Do you offer one? What about flash hiders?
depends on how recoil sensitive you are. ANY benefit in
terms of recoil will come at the cost of increased noise
to the shooter and surroundings. Because of the large bore
and relatively low pressure, most muzzle brakes will not
be quite as effective with the .458 SOCOM as they might be
with a cartridge like the .22-250. We do offer different
versions and some folks report that they make a tremendous
difference. A lot of it depends on the shooters preference
but the more popular version is the Shrewd brand. We also
offer a number of different flash hiders, including an A1
birdcage style made by Tromix and a custom-made Smith
Enterprises Inc Vortex.
loaded ammo was scarce for a while, the .458 SOCOM with
its wide range of bullets available seems to have found a
loyal home with the folks that (like to) reload. All the
components are available as is load data so reloading is
not an issue. Folks have reported as many as 9 reloads on
a single case, making it economically attractive for those
already set up to do so. With the wide array of .458
bullets available, (re)loading your own ammunition allows
you to tailor a load both to your needs and your gun,
which means you can work on getting the utmost in terms of
accuracy or velocity out of your particular rifle. Some
guys really like their pet loads for hunting, while others
just like the fact that reloading can drastically reduce
the cost of plinking with the SOCOM.
I am new to
reloading, would this be a good cartridge to learn on?
be honest, the SOCOM is relatively new in the world of
firearms compared to such rounds as the .30-06, the .45-70
and many others. It would probably not be the best one to
learn on, as it has a few idiosyncrasies, but if you like
Where do I get
brass, bullets, etc.?
brass is made by Starline and can be bought straight from
them or else through the larger reloading specialty
outlets like Midway and Graff and Sons. Just about ANY of
the .458 diameter bullets out there will work, and these
are readily available at most gun stores that offer
What is the trim
length for the brass?
official length is 1.575" but you can go as
"short" as 1.570".
How do I resize
important than trim length is shoulder set back as this
cartridge head spaces on the shoulder. Experienced
reloaders will know what this means, but for those that do
not – you have to set up your dies such that when you
full length size the brass after firing, you do not push
the shoulder back down the case. If you were to do so, the
case would still chamber, but likely FAIL upon firing. Not
a huge issue, just a pain. I have had several do this,
before I got my dies dialed in properly. Sometimes the
shell holder can make al the difference needed …. I run
my dies all the way down to where the fully contact the
shell holder and this works for me but again; there are
variances in shell holder thickness which can cause
What bullets can
stated above, just about any .458 diameter bullet, ranging
from 250 grains to 600 grains is what we have found out
there. Cast lead could be used, but we would recommend
limiting the number of cast lead bullets as the lead may
foul the gas system. Seating depth can be a bit of a
challenge with some of the heavier bullets. NOTE that the
crimping groove on many .458 caliber bullets was designed
with a totally different cartridge in mind (typically
.45-70 or .458 Win Mag). Therefore, the crimping groove
will likely NOT line up with the case mouth when seating
to an overall length that fits in the magazine (or
chambers, there are some bullets that need to be seated
deeper due to their profile, such as the 300-grain
SinterFire frangible and the 400-grain Speer FN)
crimping? Bullet set back?
is a topic of quite some debate. Both the CH dies and Lee
dies allow you to crimp. Typically crimping is recommended
to prevent set back of the bullet due to recoil or during
the feeding process. However, several shooters report no
issue when not crimping and one accomplished reloader/shooter
reported a decline in accuracy when crimping. I tend to
put a light crimp on my loaded rounds with my CH dies and
have not encountered an issue … yet.
should I use?
cartridge case uses the large pistol primer pocket and we
recommend the CCI350 or the WLP primers. DO NOT use rifle
primers as the primer pocket is not deep enough to seat
them property which could lead to a very dangerous
should I use?
a relatively small powder volume and low pressure, the
faster rifle powders tend to be the more popular and
effective. Typical powders include Hodgdon H110,
Winchester Win296, Norma N200, Alliant Reloder7, IMR4198
and VVN110. We have also been hearing that Hodgdon Lil’
Gun is producing great results but my personal experience
has been that Reloder7 is just about the most forgiving
and versatile for the SOCOM and I feel it probably is the
best choice. Your mileage may vary …
Where do I get
first set of dies was made by CH Tool and Die (www.CH4D.com)
and they carry them. Lee also has the dies, but they are
down to their last few sets….. If you ask us, we can
work with you if you want a different brand like Redding
Which dies are
better, CH or Lee?
dies have their pluses and their minuses. Another Ford
versus Chevy debate some would say. There are some
differences; I’ll try to highlight the obvious ones.
– The CH dies come as a two-die set with no shell
holder. I like my CH dies, but customers have reported
that the surface finish was rough, leaving the brass
appearing scratched. It does not affect the function of
the brass but might be less than ideal. The die set does
not include a belling die which never bothered me but
can make seating flat base bullets more challenging. The
seater plug is designed for use with the 300-gr. Spitzer
bullet and will not do the tip of the 300-gr. JHP
bullets any favors. Having another seater plug such as
one for the 44 Magnum can be a plus. The seater dies
also serves to put a taper crimp on the case during the
top of the stroke.
– the Lee set does have a belling die as well as a
separate crimp die. Again, seater plug issues, as the
one furnished is too short for the 300-gr. JHP bullets.
Using one from a 44 Magnum die set tends to solve this.
The die set also comes with the wrong shell holder for
some strange reason …. I do not like the decapper set
up on the Lee dies but that is a personal preference.
Can I load these
using a Dillon progressive?
sure can, but it requires a few tricks. You need the shell
plate for the .45 ACP and the powder funnel for that one
as well. Make sure the dies allow full travel of the ram
as that was found to be a problem in one case. The fine
folks at Dillon can help you with specifics; I still plod
along with my trusty Rock Chucker …
Where can I find
now, the best place is to Email us at TeppoJutsu@ev1.net
however we hope to post it on our website soon.
think this covers just about everything, if I missed
anything let me know
Teppo Jutsu LLC
of the .458 SOCOM