on assault rifles in general
you might be surprised, but one of the earliest mass produced (about 50.000 made) assault rifles was the... Browning BAR 1918.
As is, it was an one-man weapon, which was to be fired from the hip ro the shoulder, in semi-auto from the trenches, and in full-auto during advances (assaults
) on enemy trenches, to keep opponents down by the sheer volume of fire.
By modern standards the BAR is way too heavy, too powerful and too inaccurate in full auto fire, but the concept was there!
the Fedorov avtomat was issued to Russian troops since 1916, but it was made in smaller numbers (about 3.000 made), and fired somewhat less powerful (in WW1 terms) 6.5mm Arisaka round.
Speaking on Stg.44, the Stg is a pure propaganda name (Assault rifle), while, in my opinion, original 1941-42 designation of Mkb (
Mashinenkarabiner, or machine carbine) is a more proper name for entire breed.
AK was not the first Russian assault rifle, but it was first to be adopted... Nor it was the best one, but it is another story, both long and sad one.