One of the interesting things about 6.8 is its potential effect on HE weapon systems. 

Given the ~12lb weight of the 6.8 rifles once the smart optic is factored in, adding a ~3lb underbarrel grenade launcher would bring the weapon weight to 15lbs - about the same as the Milkor M32 with optic. That means that the collective weight should be high enough to fire Medium Velocity grenades without any need for a recoil dampening system. And the laser range finder and ballistic calculator of the NGSW FCU already provides most of the raw materials for a grenade launcher FCU...

On the flipside, by having a 6.8 LMG at the squad level, theres suddenly much less need for a GPMG 'weapons squad.' This offers the tantalizing prospect of reconfiguring the Weapons Squad from GMPG's to HE slingers - either an Airburst AGS-30 type system, the Imortar 60mm with FCU, or Carl Gustav's with airburst / guided rounds. 

Your weapons squad still needs GPMGs because the best position to support and overwatch your maneuver element is rarely with the maneuver element, and if they are with the maneuver element they're slowing everyone down (a bit of a moot point in places like Afghanistan since everyone is loaded down like mules moving to contact with approach loads anyway, but that will get you killed against a competent enemy)

I think the GPMG will be supplanted by the LWMMG in the weapons platoon. And maybe a 51mm recoilless gun? 

Well, the US Marines are going to 84mm for every platoon..

Farmplinker said:

Well, the US Marines are going to 84mm for every squad.

FIFY.   ;^)   https://youtu.be/jfVxspzh0Pg?t=75

Thanks!

Is there an existing 51mm recoiless rifle?

Not that I am aware

In that case, how about 57mm?  Gun and ammo do exist.

The design and construction just need to be modernized.

https://www.youtube.com/watch?v=qsM8EtBZ-EQ

I have thought before a scaled down Carl Gustaf might be useful. 

Something like 66mm, akin to the LAW, but reloadable and more accurate. Similar to the relationship between the 84mm AT4 disposable and 84mm Carl.

66mm is .786 of 84mm, so just taking the M4 weights and multiplying by .786 as a guestimate: 

84mm

Carl Gustaf M4= 14.55lbs

Aimpoint FCS13RE = 3.53lbs

HE 441D Airburst = 6.83lbs

x3= 20.5lbs

= 38.53lbs

66mm

Carl Gustaf 'M66' =  11.44lbs

Aimpoint FCS13RE = 3.53lbs

66mm Airburst = 5.37lbs

x3 = 16.11lbs (x4 = 21.48lbs)

= 31.08lbs / x4 36.45lbs