Where can I buy. 44 Mag attatchments in the Mojave Wasteland

Start visiting all the merchants, including the traveling ones. Mods are random and the vendors reset Wednesday (Tuesday?) and Sunday nights

Alright thanks. Any recommendations on attachment I should get

There is only the scope for zooming and the frame for increased condition. If you do the quest to find talent for the Tops, one of the performers can give the 44 all modded up if you handle the conversation correctly. This would be the guy by the billboard south of the 188. And, it is a Hold Out Weapon so you can take it into the casinos.

Alright thanks for the help