All snipers have the same gun ability if you have at least a +1 bonus with it:
Snipers have advantage instead of disadvantage on attack rolls at long range.
Snipers have the following calibers available to them:
Average & Heavy
Also: Every 10ft closer to the target you get from the normal full range, you gain a -1 debuff to your attack roll
Barrett-50 : 60 Gold
1d10 Piercing, 150ft (450ft) Range
(1 Shots Until Reload)
RMB-93 : 80 Gold
1d10 Piercing, 200ft (600ft) Range
(1 Shots Until Reload)
M21 : 105 Gold
1d10 Piercing, 200ft (600ft) Range
(2 Shots Until Reload)