All sidearms have the same gun ability if you have at least a +1 bonus with it:
When you use your action to make an attack roll, you can make two instead of one.
Sidearms have the following calibers available to them:
Average & Finesse
M-1911 : 30 Gold
1d4 Piercing + Dex, 30ft (90ft) Range
(2 Shots Until Reload)
Glock-19 : 45 Gold
1d6 Piercing + Dex, 60ft (180ft) Range
(2 Shots Until Reload)
Smith & Wesson 45 : 75 Gold
1d6 Piercing + Dex, 30ft (90ft) Range
(4 Shots Until Reload)