Picture of Secretary of the Army Daniel Driscoll, in the green jacket, is shown, from left to right, mockups of the Northrop Grumman-Colt precision grenade launcher, the FN America PGS-001, and the Barrett/MARS SSRS. An M4 carbine and an M320 grenade launcher are also seen at right.
Picture source from the US Army.
So I'm just learning about this for the first time because I sorta just figured the military would have some semblance of Strategic common sense left in maintaining the 40mm under-barrel grenade launcher platform they've been using for decades.
Nope. Fuck that.
Apparently the DOD is looking into competing contracts for a 25mm semi-auto magazine-fed grenade launching man-portable shoulder-mounted rifle. They're estimated to only carry 5 rounds per mag, have whatever shitty computerized Optics they're gonna slap on their dogwater rifles, be used to shoot down drones, and have shotgun canister rounds for close quarter combat.
Thing is, it's gonna be fucking heavy, at roughly 14 pounds loaded unless they can shave off more weight. It's gonna decrease the infantry squad Firepower by at least two riflemen by making each fireteam's designated grenadier able to only shoot grenades and maybe a pistol sidearm if they're lucky.
They're not gonna carry the new fancylad XM7 Rifle because that's already like 10 pounds of shit as is plus ammo in addition to the proposed 14 pounds of shit grenade launcher rifle plus ammo, that's just too much shit to move with and just a fucking mess to deal with in general. If they get told they get to use the M4 carbine system as their primary carry, that's still around 7 pounds plus ammo of extra shit they gotta handle.
XM7 below
M4 below
The fucking Pentagon's brilliant thought leaders are already bickering over whether or not the new rifle carrying 10 less rounds is a good thing (more stopping power plus range per round) of a bad thing (less massed fire for suppression and less ammo capacity). Introducing what looks to be another fuck up to the standardized infantry squad loadout is sure to really hamstring the footsoldiers of the u.s military if they actually follow through with this.
Fuck me, the rational side of my brains looking at this pulling the hair out of its head but the sicko commie side is going 
It also damages the power pack.
It can straight-up cause them to explode lol. Many a poor guardsman in dire straights has accidentally wiped out their own squad by trying to charge multiple packs in a fire and blowing up their encampment.
I bet they get sprayed with some crazy caustic chemicals when that thing goes up.
In lore guard sometimes used plasma rifles or pistols too. Which are excellent weapons, but if someone isn't watching the gauge (which guardsman in lore rarily do) it gets overheated. And then it cool itself automatically by just venting plasma, straight at the user. You can also overheat it purposefully to one hit kill about everything short of heavy tank, but if it overheats then (which it usually does after few shots and it's random so you never know if you have one shot more in it) it explodes wiping out your entire compan if you're unlucky (which again guardsman usually are).
And now imagine same weapon but used by chaos forces, most of them being the relic of great crusade when it was experimental and prone to misfires and random plasma venting (plasma weapons are rare in 40k lore example of actual technical advancement and refinement though it took few thousand years).
And now imagine Plasma Annihilator, basically the same weapon but so big it's mounted as main weapon on heaviest titan classes. In one book when it accidentally discharged on board of one of the biggest ships of AdMech it almost crippled it entirely.