Fallout 4 Discussion
Trainer Tools and Resources
I think that's a known problem and maybe only available in Far Harbor at Allen Lees Gun Store or Brooks Store.
You could always use the Console for the 45-70.
Command would be like: player.additem [BaseID#] [quantity]
The Wiki page does list other places:
[Edited by element5, 8/6/2016 1:09:40 PM]
* Updated game trainers and cheats daily
* Get notified when new cheats are added
* Request which games get new trainers
* Priority support with any problem