@B.S awesome loadout pics, and once i have some more money i intend on making my own ww2 loadout, most likely british airborne troops at arnhem.
I have a mk2 sten i bought recently through the classifieds, and i had the same issue with loading the mags.... until i saw a video from northeast themselves that show them using a speed loader.
They hold a finger either side of the feed lips to keep bbs from popping out either side and then use the speed loader to force the bbs straight down through the top of the feed lips into the magazine.
Its a bit fiddly, but its less of a ballache than loading 32 bbs by hand
Pic of my sten included below, posing besides james hollands new book i acquired last week.
Im also wondering if there is a way to get a barrel assembly seperate as a spare part, so i can get the end of the outer barrel machined out. That way i can fit a longer inner barrel to use with the mock suppressor