Walt was isolated for months in New Hampshire with no phone and no internet. How do you think he managed to contact Lawson upon returning to New Mexico? I doubt he’d have the man’s number memorized, and I doubt he was easy to find in the phone book (although it’s not impossible I guess). Walt also didn’t have his cell phone at the time as he destroyed it after making the phone call to Skyler in Ozymandias. Even if that was just a burner phone, there’s no way the disappearer would’ve let Walt take his actual cell phone with him. The show never explained how Walt contacted him.

My next question: do you think Lawson ended up getting caught after Felina? In addition to the M60 machine gun, Lawson also sold Walt a car. I have to imagine that the car could be traced back to Lawson in some way, or could be traced back to someone who could point law enforcement towards him. Unless the car was stolen, I don’t really see how law enforcement would be unable to tie it to Lawson. Also consider that it was known that Walt was at a Denny’s (Marie told Skyler this in Felina) and had abandoned a stolen car from New Hampshire there. Wouldn’t surveillance footage show Walt leaving in the car that Lawson dropped off? Another good question would be why would Lawson even take the risk of selling a machine gun to a fugitive who’s the face of a nationwide manhunt, but that’s a question for another time.