Barrett Firearms' M468 6.8mm Remington SPC
For those who don't know about the Barrett M468, here is a bit of paraphrased background information on it:
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Originally Posted by http://www.gunblast.com/Barrett-M468.htm
The 6.8 Remington SPC (Special Purpose Cartridge) was developed by Remington and the US military as a replacement for the 5.56mm NATO cartridge in specialized situations. The cartridge is based loosely on the .30 Remington case, and uses a 115 grain bullet of .277 inch diameter. One of the parameters of the design was that it must be compatible with the M4/M16 family of rifles, along with current squad automatic weapons and light machine guns, with minimal modifications. The specifications call for a bullet speed of 2650 feet per second from a sixteen and one-half inch barrel, delivering 1715 foot-pounds of energy, and a six hundred meter effective range. Basically, the US military wanted a round that was smaller than the 7.62x51mm NATO cartridge, but delivered more terminal effect than the 5.56mm. The end result was the 6.8 SPC.
The weapon for delivering the new cartridge is being manufactured by Barrett at their Murfreesboro, Tennessee facility. It is basically an AR15/M16/M4 rifle, with a few added features. Barrett calls the new rifle the M468, and is being built in both a civilian-legal model, and also in a close quarters battle (CQB) configuration.
The future of the 6.8 SPC as a military cartridge has not been finalized. However, at this time there are some specialized units of the US Army putting the M468 through some serious testing. Barrett Manufacturing is working closely with the military in developing this weapon. Barrett has for many years supplied the excellent Model 82A1 to the US military and our allies, and has the ability to supply the M468 as needed. In the meantime, the M468 is in production for civilian sales, and Barrett offers complete rifles, along with upper receiver units to fit most AR15 lower receivers, in a rifle with semi-auto firepower, a weight of 7.3 pounds, and an overall length of only 33.5 inches.
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Real steel:
And now images of my replica:
There are some minor differences between the real steel version and this version I've constructed. Namely, the receiver markings and the presence of one extra guiding track on each side of the magazine. The larger 6.8mm cartridges require different magazines to accept the larger diameter. The replica could be completed by switching the lower receiver (Guarder now has a Barrett M468 metal body) and by puttying/painting the groove on the magazine.
The suppressor's quick mounting mechanism is very similar to the SPR mk12's system, where the flash hider never needs to be removed and inserts directly in to the can.
The threaded mounting collar sits flush with the integrated gas block / flip up front sight. Also integrated in to the front sight is a ratcheting locking mechanism that prevents the can from unscrewing itself due to vibration during firing.
The threads of the collar - like the SPR - can be covered with an included thread protector:
Construction
The externals of this guns were pretty easy to put together. The gun itself is based off a Tokyo Marui M4 S-System, and a VFC Barrett M468 conversion kit.
Full list of all the parts used in my specific model:
Externals:
Tokyo Marui M4A1 S
VFC / GB-Tech Barrett M468 Conversion Kit
Guarder Enhanced Pistol Grip
Guarder Tactical Flip Up Rear Sight (Same thing as the Marui version, but construction, finish & markings are nicer)
Internals:
Prometheus EG Element Low Resistance Wiring
PHOENIX High Protection High Cycle Gear Set ( Limited Version )
Prometheus Hard Reversal Stop Latch
Prometheus EG Spring Guide Smoother
Prometheus MS100SP Spring
Prometheus Hard Piston
Systema Silent Piston Head
KM - TN Coated Inner Taper Cylinder for Middle AEGs
KM - TN Cylinder Head Straight Type
KM TN Metal Nozzle Type B
KM Separate Urethane Rubber Camber - RH55 Type
Systema BS 6.04mm Barrel custom cut to 330mm (You can see a bit of it poking out the first ventilation hole in the flash hider)
Performance:
~350fps with 0.20g BBs.
As you can see, this setup was built to LAST, with a mechanical life cycle of approximately 300,000 rounds or more in a lab environment. MIL standard testing shows 100,000+ round life cycle. (Note: I'm not sure how Phoenix tests that MIL standard.)
Full gallery here:
http://www.pbase.com/illusive_airsoft/m468