The 6.8 SPC rifle (above) provides nearly identical trajectory as the 5.56
(below), but offers superior terminal performance in the same package with
little extra recoil.
Once the case dimensions were tweaked to fit and work in M4-compatible
magazines, the project team quickly turned their attention to bore size.
Derivative wildcats from 5.56mm to up 7.62mm diameter shooting bullets from 90
to 140 grains were subjected to a battery of tests, and a sweet spot emerged.
The 6.5mm bullets showed the best accuracy and the 7mm bullets were the most
destructive, but the 0.277-inch bullets showed almost the same accuracy and
trajectory as the 6.5mm and almost the terminal performance of the 7mm. When
necked down to 0.277-inch and shooting 115-grain bullets, it provided the best
combination of combat accuracy, reliability and terminal performance for up to
500 meter engagements. This cartridge was deemed 6.8 Remington Special Purpose
Cartridge (SPC), because 0.277 inch is 6.8mm in metric and .30 Remington
provided the parent case.
Numerous articles and Internet rumors have suggested that the SPC designation
means 6.8 is good only for Close Quarters Battle (CQB), but not distant targets.
This is incorrect, and contrary to the intent of the project and capabilities of
the cartridge.
In open country where targets often appear beyond 200 yards, 6.8 SPC extends the
shooter's ballistic advantage and delivers more power on target than 5.56.
The SPC designation was assigned based on the intended
integration into the Mk12 Special Purpose Rifle (SPR). The SPC was designed
from the ground up to provide increased energy, barrier penetration, and
incapacitation from the Mk12 SPR, from contact distance to 500 meters.
Based on their experience with 7.62x39mm, the project team set a velocity goal
of 200fps faster than the AK-47 ammunition from the same barrel length, with a
projectile that provided a better ballistic coefficient (BC) and terminal
performance. This was achieved very soon into the project using Sierra
115-grain and Hornady 110-grain Open-Tip Match (OTM) bullets. Using Ramshot
1660 powder for initial development, the team easily exceeded the 200fps goal.
Shooting from an 18-inch SPR barrel, these loads shot 2635 to 2650fps, 300fps
faster than the AK-47.
Unlike military-industrial-complex programs such as the XM-8, the ERC project
was driven directly by Special Forces shooters at the spear's tip-- men who had
been on the giving and receiving ends of fire.
The 6.8 SPC was developed with
less than $5,000 initial investment of government funds; later development costs
were paid for by industry. This is in stark contrast to top-down "next
generation" programs costing the tax-payers millions and rarely producing usable
weapons systems.
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