Pistol to a long gun fight

If you do indeed have only a pistol at your command when confronted with long gun opponents, I would suggest one with a few....upgrades. I count at LEAST 4 NFA upgrades for a total of $800 in taxes and probably a year or more in waiting time for BATF approval.  ;)
It may be hard to put in your holster, but it will definitely spice up your after action report.