Mr. Moffat is an old german weapon master (he was in mafia during gang war in Germany and he supported mafia with his custom made guns) who come ilegally to Liberty City because German mafia searched him in Germany, laying low didn't helped. Now he came to Liberty City, and supports Triads with some custom made weapons, as well as weapons illegaly smuggled from Germany, his place is in down Algonquin, near Liberty City bank.
 Mr. Moffat customized hardly 3 guns, and changed along other parametres in other weapons.
 Stubby Sweeper:
Stubby Sweeper is an customized version of Sawed Of Shotgun, by changing it to short normal shotgun Mr. Moffat acquired totally new range (longer), accurace, and huge force with increased damage. Also now instead of 2 shots, 4 customized shotgun pellets can be loaded to Stubby Sweeper. Also Stubby Sweeper has been favourite weapon of well know gangster Mr. Bellic, so much, so he even made a picture that represents his love to Stubby' when loading one shotgun pellet to police officer during prison escape.

 Assasin's Sweeper
An heavily modified Stubby Sweeper, along with re-worked gun model. Now it's alot longer, so Mr. Moffat customized the magazine, now 10(!) shots can be loaded, because of longer baller this version of Mr. Moffat's Sweeper is alot more accurate, but the damage isn't so big as it is in Stubby Sweeper. Assasin's Prefer this weapon more, because they can give them more painfully death. In short comment, if you want to scare to death someone- quickly afford this gun.
 Killer Pistol
A modifed version of Pistol, it can blow up 21 bullets in 2 seconds. Yes that's right, Mr. Moffat changed magazine capacity to 21 bullets and managed to get automatic fire on this one.

 Along with those killer machines, Mr. Moffat also brought some customized weapons from Germany.

All weapons available in Liberty City were bought by Mr. Moffat and modified, and he started to product them in high mass.
 All weapons have more stopping power and damage, and Mr. Moffat managed to make drum magazines for some of them.
Assault Rifle- drum magazine can carry 120 ammo at time.
Combat Pistol- Magazine size reduced to 12 369. bullets.
Machine Pistol- Drum magazine provide you to carry 150 bullets at time in this magazine.
Also Mr. Moffat modified 369 ammo to make them go through armor. NOOSE or FIB won't be big problem any more.

Moffat's Problems

It was a normal day, Moffat's was selling weapons. But then, NOOSE agents come and arrested Moffat. However, Moffat make a deal with corupted agent; he offered him his Stubby Sweeper, bigger magazines for Pistol, and customized bullets for Combat SMG, Carbine Rifle, Combat Sniper Rifle. Coruppted agent agreed, and Moffat is still selling his weapons in Liberty City.

As you remember, Moffat is customizing his ammo, and it's weight is bigger, so you can't have so much ammo on you. (Ammo max decrased on most weapons by 2x)