39 to 40 pounds package is easy.
Full rifle with integrated grenade launcher between 11 and 13 pounds ( 11 always sounded to light ), 2 electronic optics between 2.6 and 3 pounds each, 4 loaded magazines about a pound each. based on the Shape And mission needs I think that the missing round object should be something like this
View attachment 36892
A Rifle Cleaning kit is a standard part of any issue kit for any weapon and the QTS 11 would need a full kit to take care of both parts. so assume another pound. figure there is a rifle sling for another half pound.
I figure the two black boxes with silvery grey dots are Lithium Ion batteries at a pound a I am guessing the Green object is a tool of some kind maybe a hammer about 8 oz. looks like a Manual and logbook that we will say is about 5 ounces
Right now my estimate is about 26 pounds or almost 12 Kg.
Now a Pelican case ( the closest Commercial Case I can think of to style and material construction ) in the closest size I could fine to the dimensions on the label 122x43x17cm is the model 1720 Long Case (with Foam) 112.7 x 40.6 x 15.5 cm at 18.9 pounds so round a 19 pounds. and that is around 45 pounds or 20kg. So assume a lighter grade of rifle case.