Pawel
One thing thet bothers me at once are the 40mm rounds laying in the dirt like that
The rounds are big and fat and are single-loaded. So "you" are less likely to get 4-5 out at a time. Especially to have to bend over to the ground and fish the next one up to load it.
Unlike later 40mm grenade rounds, the ones used operate on a high-low principal. The propelling charge goes off in a central "cup" in the case, which then "bleeds" into the annular space around the round, which "lobs" the round out "gently." (If in a stout kick to the shoulder.)
But, that meant that the M-79 really did not need its sight, while the grenade lobbed ut at 3-4 times the speed of hand-thrown, it was not rifle-shot fast. So, it was like whacking a self-tossed tennis ball with a racket, or a basebal with a bat. The user, with experience, had a pretty good idea where the round was like to go.
So, loose rounds were more likely to be in a blouse pocket or thigh pocket, where they'd be in reach for the reload.
Now, in this case, the pistol holser is appropriate, as the "blooper" wanted a proer arm of some sort, and carrying a slung M-16 was not convenent (and, presumably, the other members of your Squad had plenty of M-16s themselves).
The holster will be black dyed leather (although over-dyed black on russet were common in the field).
Contemporary photos of LBE rigs for grenadiers are all over the place, so, this one has no obvious Francois "farbys."
The ammo cases are stiff canvas, so the shape is right. There's a strap from the top back of the case that goes up to the "H" suspenders, which Francois may have skipped over.
The pose could be read as "high ready," which might explain being a meter or two back behind actual cover.
Likely, this wil lbe a cool build.