Security Forces is why my son joined the Marines. He saw a picture of a stack of Marines in full body armor getting ready to kick down a door and make an entry a la SWAT. From boot camp at Parris Island he went to SOI. From there he went to security guard school in Norfolk. After that he was sent to Kings Bay GA. He convinced them that even tho he was a year younger than what they were looking for he would be a good candidate for CQB school, so they sent him back to Norfolk for that school. And yes, he did want to go to a FAST team, but once he got settled in at Kings Bay he enjoyed the 2 years he spent there.
And as someone already said they do train to shoot the pistol and rifle about 4 times as much as other units do.