About

The purpose of this blog is to propose and discuss a new set of rifle cartridges, termed the “Intermediate Cartridge Series” or ICS, which are intermediate in diameter, powder capacity, bullet weight, muzzle energy, and recoil between the .223/5.56 and the .308/7.62×51 cartridges.

The first cartridge in the series, and the basis for all other entries in the series, is the 6.8 ICS. Subsequents ICS cartridges will be essentially the same case, necked down to 6.5mm or 6mm, or necked up to 7mm.

Intermediate Cartridge Series:
6.0 ICS
6.5 ICS
6.8 ICS
7.0 ICS

The 6.8 ICS specifies the same exact size brass case as the 6.8 SPC, except that the body is lengthened to 1.615 inches (41,02 mm), making the total case length 2.000 inches (50.80). The COAL is set at 2.750, the same as the .308/7.62, so that AR-10 type rifles can be modified to fire the cartridge.

The lengthened body allows about 8 more grains of powder, for higher velocities and heavier bullets. The longer COAL leaves 0.75 inches to accommodate long bullets with good ballistic coefficients.

— Estimated Velocities —
6.8 ICS
bullet — 20 inch barrel
125 gr — 2800 fps
130 gr — 2750 fps
135 gr — 2700 fps
140 gr — 2650 fps
150 gr — 2500 fps
150 gr — 2550 fps (max load)

bullet — 16-in barrel
125 gr — 2675 fps
130 gr — 2625 fps
135 gr — 2575 fps
140 gr — 2525 fps
150 gr — 2350 fps
150 gr — 2400 fps (max load)

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