Ok, not sure if this is Laserblast or not, but I remember seeing a movie back in the mid to late 80s about a loner teenager from a small town in AZ I believe who finds an alien weapon. It sounds like Laserblast, but the only other thing I really remember is that the kid has a dog that gets killed by a baseball bat, which is what sparks him using the weapon; not sure if it was the father that did it or someone else, but it was a backwater hick town. I think the movie was supposed to be set in Bumblebee, AZ or something like that.
I think this is Deadly Weapon, which was apparently begun as a sequel to Laserblast. http://www.imdb.com/title/tt0097171/
The entire film appears to be on YouTube, starting here:
Sorry for the late reply, but yes, that was Deadly Weapon aka Kid With A Raygun shot for Empire Pictures in 1987 and directed by Michael Miner, who had co-written Robocop.
Ironically, this film is a loose remake of an earlier film by producer Charles Band and originally started out as Laserblast 2. Years later, Band produced yet another loose(r) remake titled Alien Arsenal, directed by David DeCouteau for the Full Moon Entertainment offshoot, Action X-Treme, which was lighter in tone than the two previous films.