Below is a press release from Sig Sauer, reporting that they have been awarded a contract for two closely related weapons intended to replace the M4/M4A1 carbine and the M249 Light Machinegun. Both use a new 6.8 mm round. There has been concern that the 5.56 mm round is not effective against some of the better body armor. I have not seen the M249 in Coast Guard service, but the Coast Guard does use the M4/M4A1 and the 7.62 mm M240. The new round is reportedly an improvement on both the 5.56 and 7.62mm rounds, so it would not be unreasonable to expect the new weapons to ultimately also replace the M240 in Coast Guard service. This would offer the logistical advantage of requiring only a single rifle caliber round service wide.
According to a report from National Defense, the weapons will be paired with a ruggedized advanced fire control system that increases accuracy and lethality, the XM157, which “integrates a number of advanced technologies, including a variable magnification optic (1X8), backup etched reticle, laser rangefinder, ballistic calculator, atmospheric sensor suite, compass, Intra-Soldier Wireless, visible and infrared aiming lasers and a digital display overlay.”
It probably will take some time before the Coast Guard sees these new weapons.
NEWINGTON, N.H., (April 20, 2022) – SIG SAUER is honored to be awarded the Next Generation Squad Weapons System (NGSW) Contract by the U.S. Army after a rigorous 27-month testing and evaluation process.
“The U.S. Army is taking a bold step toward command of the 21st century battlefield and SIG SAUER is immensely proud to be the selected provider for this historic revolution in infantry weapons. The fielding of the SIG SAUER Next Generation Squad Weapons System will forever change the dynamic of military engagement for America’s warfighters with American innovation and manufacturing,” began Ron Cohen, President and CEO SIG SAUER, Inc.
The SIG FURY Hybrid Ammunition (6.8 Common Cartridge), SIG-LMG (XM250), SIG MCX-SPEAR Rifle (XM5) and SIG SLX Suppressors meaningfully advance soldier weapons technology to meet the emerging requirements of the U.S. Army.
The SIG 6.8×51 FURY Hybrid Ammunition uses a patented lightweight metallic case designed to handle pressures higher than conventional ammunition, resulting in dramatically increased velocity and on-target energy in lighter weapons.
The SIG-LMG lightweight belt-fed machine gun and SIG MCX-SPEAR Rifle are purpose-built to harness the energy of the SIG FURY 6.8 Common Cartridge Ammunition enabling greater range and increased lethality while reducing the soldier’s load on the battlefield. Both the SIG-LMG and MCX-SPEAR deliver significant weapon and technology advancements to the soldier and provide a solution for battlefield overmatch in comparison to the current M249 and M4/M4A1.
The U.S. Army’s procurement of the NGSW System marks the beginning of an era where combat weapons are coupled with a suppressor as standard issue equipment. The SIG SLX Suppressors are designed to reduce harmful gas backflow, sound signature and flash. SIG SLX Suppressors feature a patented quick-detach design for easy install and removal.
“We commend U.S. Army leadership for having the vision to undertake this historic procurement process to deliver a transformational weapon system to our warfighters. This award is the culmination of a successful collaboration between SIG SAUER and the U.S. Army, and we look forward to the continuing partnership,” concluded Cohen.
SIG SAUER is a company that is driven by innovation and we are proud to offer the advancements of the NGSW System in the SIG 277 FURY Hybrid Ammunition (the commercial variant of the SIG 6.8×51 FURY Ammunition round), SIG MCX-SPEAR Rifle, and the SIG SLX Series of Suppressors available to the consumer. For more information about these products visit sigsauer.com.
Chuck Hill's CG Blog 
“It probably will take some time before the Coast Guard sees these new weapons.”
Since this is a US Army program, and not a Department of Defense program I would say that is a good assessment
Now, being smart bugger the Army did contract for options far in excess of what they currently plan to acquire. Thus should other services decide they wish to field them they can request some weapons
The Army has also already issued an RFI for sources to offer modification kits/processes to adapt M240s to use the VERY high pressure 6.8X51 ammo.
Looks like the Army is considering converting the M240 to fire 6.8 mm https://www.thefirearmblog.com/blog/2022/03/18/us-army-m240-6-8mm-conversion/?fbclid=IwAR2Nyb7E_frZdb_JQvszfT5LFmMKHASphSdBZBDsYpejIiO4lVFj_9Ikcwg
I am hoping that once the US are underway with this programme to replace 5.56 it sparks our government here in the UK to finally replace the L85Ax family.
A bit more about production plans. https://www.defenseone.com/business/2022/04/soldiers-will-have-wait-until-next-year-new-rifle-ammo/365906/