JASmith Wrote:...my thinking is that the 7.62X51 NATO will almost certainly continue to be the "light caliber" for vehicle-mounted weapons.Concur. The only complaint about 7.62x51 that I know of is the weight, and for vehicle-mounted weapons that is not a significant issue.
Quote:I think it may be possible to go with a unified caliber for dismounted units...Sure, it's possible. In WWII and the Korean War, the infantry rifle, automatic rifle, and machine gun used the same caliber. The drawback to a unified caliber is that it results in ammunition and weapon that are heavier and bigger than needed by the rifleman.
Quote:It would truly be interesting to see what one could get from a family of Grendel-based cartridges in 5.56, 6, 6.35, and 6.5 mm. We should also examine a similar family based on the 6.8 SPC.If, as I think likely, 7.62x51 remains in use for the MMG/GPMG, then the need is only for a cartridge to replace 5.56x45. IMO, that argues for a cartridge of minimum weight and bulk. The diameter of the Grendel case is less desirable than that of the SPC case, which is less desirable than than that of the 6mm SAW case, which is less desirable than that of the 5.45x39 case. Of course, cartridge size and weight must be balanced against the need for sufficiently improved terminal and exterior ballistics.
Quote:LR1955 and others have argued that probability of hit out to 400-600 meters is of critical importance and that any new system needs to shine in at least one area.They might. The few ballistics tables I still have from 2-4 years ago show a clear advantage in trajectory and drift for 6.5 Grendel over 6.8 SPC and 5.56 NATO. However, the 6.8 velocities I used were for SAAMI loads, not the newer Spec II ammo.
Given the fundamental need to get a hit, it seems odd that we've spent a lot of time discussing on-target effects, ammunition weight, and recoil but almost none on trajectory and wind-drift. These areas are ones where higher-velocity and moderately well-shaped bullets might result in a significant improvement.
The introduction of Wilson Combat's 110gr @ 2700 fps (6.8 SPC) load may put that cartridge in a different light. SSA's 85gr TSX @ 3000 fps might also be interesting. I have a feeling that 6.5 Grendel trajectory and wind drift may not be significantly different than these 6.8 SPC loads out to 400-600 meters.