6.5 x 40 New AR varient

[stanc]

The problem with the M249 feed system is its tolerance. This is due to the fact that it's constructed with cheap stamped components. This is fine when the rifle is new; however, with a little wear the rifle quickly becomes increasingly sloppy. The weapon requires an incredible amount of attention and maintenance; otherwise, it's an incredible frustrating platform. To effectively employ the M249 with any reliability you have to know the weapon in your hands better than you know your own hands. The links are of little consequence here.

Of little consequence??? That's just not true. The links are of major importance to a belt-fed weapon. Without them, at best all you have is an exceedingly expensive, overly complex, and unduly heavy, magazine-fed rifle. That's in the specific case of the M249. For others, like the Mk46 and MG4, you wouldn't have even that much. Viable links are absolutely critical.

Stanc do you see that hole in that link. That instantly tells me that there's potential to decrease the width of that portion of the link and still maintain adequate strength. You must realize that Material Science has come light years since the 60's. I'm certain links can be made smaller and stronger...

All of that has been said before. Unfortunately, as with the others before you, all you have provided is speculation and wishful thinking. It is still yet to be proven that the link loops can be made sufficiently narrow, yet have the necessary combination of strength and elasticity.

This task is no different than designing a magazine to reliably feed a new round, i.e. the Grendel. Have such magazines been designed? Yes, most work very well.

Yes, they do. However, the tasks are quite different.

Grendel magazines have the same external dimensions as 5.56 magazines.

In contrast, Grendel links -- if the loops are narrowed as you suggest -- would have substantially different dimensions than 5.56 links. There is no assurance that such an altered design would work.