This should be a new weapon mod for the Ramshackle Sniper Rifle. it's like a better version of the Pipe Rifles in fallout with much more homemade style weapon that many settlers,
Top 10 Sniper Rifle Mods Fallout 4 Xbox One (XB1) Episode #2 #Fallout4 #Fallout4Mods #Fallout4Top10 - YouTube