Something i think about is how the concept art of the game admits the pipe guns aren't meant to look like real guns, just "gun shaped". The devs did it intently :
Fallout 4: Compensated Pipe Rifle - Orcz.com, The Video Games Wiki
Pipe Guns Overhaul at Fallout 4 Nexus - Mods and community
Nina's Proper Pipe Guns Replacer at Fallout 4 Nexus - Mods and community
Here's a Wounding Pipe Gun found from my current playthrough. It's likely going to be paired with heavy weapons as the secondary type of weapons since I plan on putting points into
Fallout 4-Inspired Pipe Rifle at Fallout New Vegas - mods and community