The gunshop in New Reno will offer the training if you have the requirements ; I buyed level one and two there, playing a char with 1 charisma. (Jacob is een moeilijke vent)
Be sure that you have correct ST and AG. Requirements are written as X>4, what means minimum is 5.. I had no problems in achieving both smg and bgg levels 1, their req were stricte as 2238 additional notes manual says, check it out. Some sort of data changed due to the updates but if you need req for professions, it's still correct.