Honestly, we can't afford a MP40 but we do have access to a highly modular Lage Max31A MK1 & M11A1 registered receiver.
With that setup, a sub 600RPM bolt, MP38/40 magazines, WW2 load bearing gear and proper iron sights (notch and post), we can fairly closely simulate the handling and functionality of an MP40.
This video explores that topic and discusses the usage of the SMG in its intended dynamic role.
InRange is an online video program dedicated to the study of guns, shooting, gun culture, and history. We dispel the myths, promote the good stuff that hasn't gotten the attention it deserves.