New Army "Caliber Configuration Study"

[Tony Williams]

I agree the discussion is about 6.5G vs 7.62mm. However, 6.5G was designed to fit 5.56mm weapons. As such, it would be used in something like the Mk46, not the M240, so barrel length of the latter is completely irrelevant.

I do agree that the Army should be presented with data on how the Grendel (and any other rival proposals) performs from barrels of different lengths, with the ballistics of each compared with the PKM. They could then decide what they wanted. I suspect that they would be unwilling to make a choice which would leave their troops outranged by the PKM, and would have to face up to the fact that choosing a short barrel for any desired ballistics would mean having to select a more powerful cartridge, resulting in more recoil and muzzle blast and a greater ammunition weight - they wouldn't want that either. They would be pushed into making a reasoned decision about the relationship between cartridge design and barrel length, in full awareness of the negative implications of short barrels.

I suspect that they might end up choosing one design of belt-fed MG in two versions: light (with a light barrel of 16-18 inches and a bipod) and heavy (with a heavy barrel of 20-24 inches and normally on a tripod). Since the gun would of course be modular, they could easily attach a bipod to a heavy-barrel version if they needed to combine long range with portability. They would thereby get the benefits of a common cartridge and ammo belt and a common MG (except for the choice of barrels and mountings).

Edit to add: the same choice would of course apply to rifles. The logical solution would be a bullpup, otherwise they would have a choice between a long barrel for the best ballistics (DMR) or a short barrel with reduced ballistics for compactness.