I must agree that the "Big Army" runs on Dollars and not sense.
" After fielding, operators reversed the previous decision and called for a SCAR platform that could change calibers. The Mk 17 was chosen to be scaled down because it had a larger receiver for the 7.62 mm round, and so the 5.56 mm Mk 16 could not be scaled up to chamber the larger round. The 5.56 conversion kit was finalized in late 2010 and orders began in mid-2011.[44"
The SCAR-L (MK16 5.56 NATO) order for 123,641 Rifles was canceled, while a considerable order it would have only been a drop in the bucket of "Big Army" inventory.
The Navy on the other hand procured both SCAR-L (5.56) & SCAR-H (7.62) for the TEAMS.
"On 9 December 2011, the Naval Surface Warfare Center Crane Division released a sole source 5 year IDIQ procurement notice for the Mk 16 Mod 0 (SCAR-L), Mk 17 Mod 0 (SCAR-H), Mk 20 Mod 0 (SSR), and MK 13 Mod 0 (40mm EGLM) from FN to sustain inventory levels.[45][46] Navy special operations forces procures their firearms through SOCOM and fielded the Mk 16 more than any other unit.[38]"
So the 5.56 M16/M4 World may continue as is, but the 7.62 NATO World is already converting. 36,843 FN SCAR-H (7.62) have already been acquired with more orders forthcoming. So the M110, M-14 Variants are being taken out of inventory.
Reference:
https://en.wikipedia.org/wiki/FN_SCAR
As to the 5.56 NATO Ammo question.
" As the issue of environmentally friendly ammo grew, the Marines looked to see if the Mk318's lead could be replaced while still meeting specifications. They found that by replacing the lead with copper and slightly stretching the jacket around to crimp the nose even more, the bullet's ballistic coefficient increased. To avoid visual confusion with the Mk 262 round, the bullet was entirely nickel-plated for a silver color; the enhanced silver-colored copper jacketed, open tip match, 62-grain projectile was named the Mk318 Mod 1. The Marine Corps will make a decision as whether to field the Mk 318 Mod 1 or M855A1 as its standard rifle round.[104]"
Reference Link:
https://en.wikipedia.org/wiki/5.56×45mm_NATO
The "Big Army" is moving to the M855A1, but the USMC has been known to base it's decisions on the "Needs of Riflemen" sort of like the 500 KD Range Qualification verses the 300 KD Qualification of the "Big Army".
I'll include an interesting Read from Shooting Times:
The Best 5.56 Load: The Black Hills MK 262 Mod 1 - Shooting Times
But I've already covered the SOCOM Minimum 1500 Meter MOA Requirement for Long Range Engagement Rifles & Cartridges. So both the 5.56 NATO and 7.62 NATO rounds are not even relevant in the World of Today's Snipers.
Good conversing with you Kevin, caught on to that (Stoner) SAW mention.