When trying to add this mod to a merge with Merge Plugins it completely screwed up the whole thing, injecting various items into the Fallout ESM. This is usually a good indicator that serious problems are present. So I left it out of my merge and tried it without any editing, the Eagle was carried by pretty much every NPC I encountered and the first body I found had two in their inventory, in addition to a pipe rifle. This was with my weapon merge which is quite large and my game also felt a bit dodgy. The issues are covered in the bugs section of the mod.
I have renamed all form id's with XEdit and can now merge the esp with others without issues. I remade the quests using DankRaft's injection toolkit in a simpler fashion, using just one levelled list for each weapon which have a chance of 10 instead of 100, and deleted the container and cell reference for better compatibility. The Bulldog Revolver and PM Eagle have been added to just Raider Weapons levelled list and should spawn at level 10.
With how many added weapons I have in my game its a very slow process to test drop rates and potential issues that still exist, so I need people to test this with me and report how it functions. I would also appreciate people who are proficient with levelled lists opening up the esp and checking it. No errors or unused data are reported in XEdit but possibly entries in the object template section can be safely deleted.
You should be able to simply install this esp and script over the original mod without opening bsa's so cleverer people than me (most of you) let me know if I buggered anything up, if the weapons spawn in different configurations, as legendary, or at all.
Bulldog Revolver https://www.nexusmods.com/fallout4/mods/43953