Personally, for a character that specializes in extremely long-ranged combat, a good sniper rifle is without a doubt the best tool for the job. Even if they have to run and gun, the -1 isn't too bad of a penalty, and if the rifle is modded enough it will be just as deadly at 5 meters as it is at 1000.
I used to give my dedicated sniper a shotgun as a backup weapon, but I found on the rare case she needed to work at close ranges the sniper rifle was still better. There are very few things it isn't at least adequate for, except concealed carry.
And the mental image of a gnome carrying a Barrett on a run-and-gun scenario is just too awesome.
I'm genuinely interested, why do you prefer sniper rifles over assault cannons for long rage combat?
Seems to me like ACs have the upper hand in range, damage and AP-ability. Is the 14F availability of the ammo why you don't prefer ACs?
The difficulty of reliably getting ammo is a small part of it, but it is also a matter of the sheer size of an Autocannon (which means even if you mod it to break down it takes a whole lot more space), it is a Heavy Weapon, it can't use varied ammo types (I love using Gel Rounds for intimidation), it can't be silenced or suppressed, it is SS rather than SA, and the damage code and AP isn't that much higher, especially compared to a Barrett 121. Also, if you have low BOD and STR and your GM actually enforces encumbrance, you may not even be able to
carry that AC without taking penalties.
In fact, a Barrett 121 firing Explosive rounds has the same damage and AP as a Panther or Vigorous cannon, and while it may cost more for the gun itself, you get a built-in silencer, internal smartgun and folding bipod (total value 4300¥ if installed on the Vigorous), and each bullet is 1/9 the cost. Plus the Rifle can fire twice per IP.
Reaver went into more detail about this in an earlier post.Finally it is an aesthetic choice as much as anything, which is my first priority when crating a RPG character in any system. I
did once create a Troll sniper who used a modified AC
as a sniper rifle, but honestly what I found is that there is nothing that an AC can do that a properly modified SR can't do better, with the possible exception of taking out heavy vehicles.