I was a asst. manager at a class 3 SOT dealer for awhile and we received a batch of WWII era guns that were non-transferable one of which was a Bergman. These guns are from a more manly era when folks would think nothing of dragging around a 10lb 9mm SMG. I didn't much care for the Bergman, but included in the batch were a couple of what would grow to be my favorite SMG's -the Suomi KP/31 which the Russians simplified to come up with their long serving PPSH guns. It was also a heavy beast (especially with its drum magazine) but I brought home turkeys twice with it during the annual Thanksgiving SMG shoots.
The other gun of a slightly later era that I really enjoyed shooting was the Carl Gustaf m/45 usually called the Swedish K. Both guns were well machined and very accurate with the K gun being slightly faster cycling yet slower and more controllable than the modern guns like the MP-5. Those were fun days!