500 round factory sealed case of Federal T556TNB1. 25 boxes of 20 rounds. Federal Lake City 5.56x45mm MK318 ammo for sale is new production ammo that features the 62 Grain SOST bullet. The ammo is reloadable, non-corrosive, and features brass cases, and Boxer primers.
Mk318 Mod 0 is obsolete and no longer made. Lake City now makes the Mk318 Mod 1 which is sold directly to the military and civilians.
The SOST round from Federal was designed for the USMC as a supplemental round to M855 green tip with more desirable terminal characteristics. Designated as MK318 MOD-0 the round was designed as a barrier defeating round with superior penetration and better ballistic stability when shooting through glass, car doors, and other barriers. "...the best military 5.56 mm load against glass is 52 gr M995 AP, followed by the 62 gr Mk318 Mod0 OTM and 70 gr Optimal "brown tip" OTM." "5.56 mm Duty Loads" by Dr. Gary Roberts posted on pistol-forum.com
Mk318 is a fragmenting bullet with a solid base. The
base stays intact and does well against intermediate barriers yet still
relies partially on fragmentation.
"For military personnel, engaging in combat from 0-300 yards using an M4, the Mk318 Mod0 is the best option readily available via the supply system;" Dr. Gary Roberts
"Mk318 Mod0 has a 2 MOA lot acceptance accuracy requirement; it is quite
accurate for a combat cartridge--much more so than many recent lots of
M855 which can be up to 6 MOA."
Dr. Gary Roberts
Table of accuracy comparison of MK318 Mod 0 with several other "mil-spec" loads Molon on lightfighter.com
"At this time, given the current ammo choices available via the standard green/white side military supply system, for a general purpose carbine, I'd load my mags with Mk318 Mod0 if available." Dr. Gary Roberts
"On unobstructed shots, the 75 gr OTM and Mk318 Mod0 will generally offer
similar tissue disruption, however the base of the SOST round will
likely exit the suspect while the 75 gr OTM does not."
Dr. Gary Roberts
The SOST rounds are optimized for relatively short barrel weapons, use heat stable, flash suppressed powder, and offer good terminal performance, with early upset and reasonably good intermediate barrier performance for a non-bonded projectile. The SOST/TOTM is an outstanding, simple, adaptive design--projectiles can be manufactured with a traditional lead core or in a lead-free version, bonded or non-bonded. Crane Presentation
According to Crane, this is a "new projectile developed from technology utilized in current law enforcement projectile. Front of bullet is designed to help defeat barrier. Back of bullet is solid copper and acts as a rear penetrator."
Manufacturer: Federal Ammunition Item #: T556TNB1
Category: Ammo Centerfire
Bullet Type: SOST
Bullet Weight: 62 GR.
Muzzle Energy: 1,322 ft lbs
Muzzle Velocity: 3,290 fps.
Rounds per Box: 20
Mk 318 Mod 0: A Better Bullet, No Matter What They Call It
A short-barreled SCAR-L equips one of America's finest, somewhere in Afghanistan
The United States Special Operations Command is using a new 5.56 NATO
cartridge, and now the Marine Corps is trying it out as well. Some
folks refer to it as the SOST round, others call it the OTMRP round, the
phrase “barrier blind ammo” has been tossed around the internet, and
the official Navy designation is Mk 318 Mod 0. No matter what name you
use, it seems that everyone except the US Army wants to load their
rifles with it.
In response to the 9/11 attacks, our country went to war in
Afghanistan in the fall of 2001. It didn’t take long for the troops to
complain that the 1980s era 62 grain M855 ammo used in their M4A1 rifles
was ineffective. In 2002 a big report detailing these problems was
written up by the Naval Surface Warfare Center in Crane, Indiana and
sent to the Pentagon. In 2003, America opened a second front in Iraq,
and more information began coming in. The new war stories, combined with
additional scientific testing, began to weigh on the Pentagon, and in
2005 they issued a formal request to the ammunition industry for
“enhanced” ammunition. Intimidated by the complicated military
procurement process, nearly every ammo maker in the country turned away.
The Federal Cartridge Company was the only business to respond to the
The Navwar/Crane and Federal/ATK bunch worked together quickly. This
“Special Operations Science and Technology” team knew what they wanted
and how to get it. Performance objectives for the new ammo were as
- Increased consistency from shot to shot, and from one lot of ammo to another, regardless of temperature changes.
- Accuracy in an M4A1 rifle always better than 2 minute of angle (2 inches at 100 yards, 3.9 inches at 300 yards).
- Increase stopping power after passing through “intermediate barriers” like walls and car windshields.
- Increased performance out of short-barreled carbines such as the FN SCAR, while at the same time decreasing muzzle flash.
- Keep the cost as close to the old M855 as possible.
It was a tall order, but the first prototype batch of ammo
was delivered to the government in August 2007. Increased velocity and
decreased muzzle flash were accomplished by tweaking the type of powder
used, but the real magic was found in the bullet design. The bullet was
named the Open Tip Match Rear Penetrator. The front of it is a hollow
point backed up by a lead core, but the lead core only goes about
halfway down the length of the bullet; the rear half is solid brass.
When the OTMRP bullet hits a hard barrier, such as the windscreen of a
car being driven by a suicide bomber, the front half of the bullet
smooshes (that’s a technical term) against the barrier, breaking it so
the “penetrator” half of the bullet can fly through and hit the target
beyond. This “barrier blind” bullet acts like two bullets in one, the
second brass bullet flying exactly through the hole made by the first
This cutaway drawing shows the "reverse drawn" open-tip design of the OTMRP bullet. Photo by Federal Cartridge
Special Forces often use modern hollowpoint ammunition forbidden to
the rest of the military. They do this by classifying themselves on
paper as “counter-terrorist” forces which can follow law enforcement
guidelines rather than military law. To be fielded by an entire branch
of the military, the new round could not be classified as a hollowpoint
by the Pentagon. Federal Cartridge helpfully pointed out to Pentagon
lawyers that the SOST bullet uses a new “reverse drawn” forming process.
The base of the bullet is made first, the lead core is placed on top of
it, and then the jacketing is pulled up around the lead core from
bottom to top. They said the bullet isn’t a
it’s an “open tip”, and the reason why the tip is open is just a
byproduct of the manufacturing process, and has nothing to do with the
terminal ballistics of the bullet’s stopping power in soft tissue. The
lawyers bought the explanation, and with a wink wink here and a nudge
nudge there, officially classified the new round as “Mk 318 Mod 0″,
legal for the military to use according to the laws of warfare. In
completely unrelated news *cough*, the round is said to be devastating
against bad guys. The front half of the bullet fragments very
consistently, creating what has been described as a “snowstorm” of lead
in the first few inches of soft tissue. The solid copper rear of the
bullet then penetrates around 18” of ballistic gelatin while tumbling.
Ouch. The SOST bullets peform this way even with the reduced velocity of
a 10.5″ chopped barrel. No wonder the Marines decided to buy “a couple
million” rounds of the ammo to try out as part of a 10.4 million round
ammo purchase in September 2010.
The only branch of the military not to show any interest in the new
round at all is the US Army, which is instead deploying its new M855A1
“Enhanced Performance Round,” also known as the lead-free or
“environmentally friendly” round. The Marines also bought 1.8 million
rounds of this ammo as part of the same September 2010 order mentioned
above. The M855A1 is a solid copper bullet topped with a 19 grain
“stacked cone” alloy steel penetrator tip. The Army touts the fact that
the M855A1 can penetrate 3/8-inch thick steel at 400 meters and also has
“barrier blind” properties. Some observers say that the Army is dead
set on buying ammo from the development program it paid for, and won’t
buy ammo developed by the Navy no matter how good it might be. Others
say that with budget cuts coming soon, the Army is anxious to advertise
itself to influential Congress members as the most environmentally
friendly branch of the armed forces. Perhaps the Army’s testing has
convinced them that M855A1 really is a better round—all we know for now
is that they aren’t interested in Mk318 Mod 0.
Interested in trying the SOST round? You can!
makes a round which they advertise as being “Made in the USA to the
same specifications as Mk 318 Mod 0”, and Federal has released a
civilian version as well under the not-catchy-at-all name
Because an executive order by President Bill Clinton banned the sale of
“surplus” American made military ammo, Federal advertises AB49 as
“loaded similar to Mk 318 Mod 0.” But lets not kid ourselves the way the
government does. In all likelihood there is only one assembly line
producing this ammunition for Federal Cartridge. When the assembly line
is finished making its allotment of ammo for the government’s order each
week, it runs for awhile longer making some extra for public sale. The
official government NSN number for the ammo is “FC-10C801-013.” That
number is stamped on each cardboard box of Federal AB49. Hint, hint,