Lawson is an arms dealer based out of Albuquerque, New Mexico.
Better Call Saul
Lawson shows Mike a few different rifles. After carefully looking at each one and thinking of another plan, Mike respectfully tells Lawson that he doesn't want any of the rifles. Mike offers Lawson money for his trouble, but he tells him not to worry about it and declines the money. ("Gloves Off")
Lawson gives Mike training with a sniper rifle he bought from him and gives him a free box of ammunition. ("Klick")
Lawson is referred to Walter White by Saul Goodman and sells him a thirty-eight snub handgun with the serial number filed off. He advises Walt to make a legal purchase instead but Walt shells out the cash ("Thirty-Eight Snub").
In 2011, Walt purchases an M60 from Lawson in the restroom of a Denny's. After asking for confirmation that "it" won't be crossing the border, Walt tells him that "it" won't be leaving town. After the purchase he gives Walt the keys to a car where the M60 is located in the trunk ("Live Free or Die").