Civil War Era "Crime Gun" Confiscated

From the Boston Herald:

Cops: Downtown shop selling more than frames

Boston police raided a Bromfield Street business that allegedly has doubled as a drug den catering to the cocaine needs of the downtown business crowd for at least a decade, recovering a cache of weapons and large quantities of narcotics, the Herald has learned.

[snip]

A search warrant at the frame shop, which Ambers also gave as his residential address, led to the seizure of three loaded illegal firearms and a stash of ammunition; 15 paper folds and two glass jars filled with more than an ounce of cocaine; and nine plastic bags bearing three pounds of marijuana, according to the BPD report.

OK, the two smaller guns are pretty easy to ballpark - a .38 (most likely) snubby with a shrouded hammer and a small-caliber pocket semi-auto (.22, .25, or .32-caliber). Any guesses on the cap & ball pistol there? Here's a blow-up.

1847 Walker Dragoon, maybe?