6.5 x 40 New AR varient

[stanc]

Stan, brother, if you're telling me we're going to continue to use the M249 feed system than we're screwed from the get go. You're talking like the problem is the links.

Cory, the problem is not the links. The problem is the cartridge. The same link design has been used in 5.56mm LMGs beginning as far back as the Stoner 63, and continuing on up to the present day with machine guns like the CETME Ameli and the HK MG4, to name a couple that come readily to mind.

Even the 6mm SAW of the 1970s used the same basic link design (below, right).



Notice how there's about an eighth of an inch of the case exposed above the front link loop, before the shoulder narrows down to the neck? That exposed case shoulder is what a machine gun's front feed pawl pushes against to advance the belt. It's also what bumps up against the feed tray cartridge stop, to position the round for chambering. With the Grendel case, there is virtually no case shoulder exposed above the link loop.

The problem isn't just limited to the M249. Any machine gun that is fed using disintegrating links would face the same issues in trying to convert it to 6.5 Grendel.