User blog comment:A Wikia Contributor 9337/Heavy build explanation/@comment-123.211.182.164-20160116122310/@comment-24659969-20160117012351

It does not need pierce if you are on Assault or Heavy since one of your skill already adds enough pierce to the guns. It is fine for medic though.

If you are playing on mobile, you can get overclock to increase the dps and capacity instead since the small clip empties in just a second if not capped. Otherwise, blast radius is also another choice to increase its cover area.

Adaptive is not really needed for pistol category since if there is enemy resistant to energy, you most likely would be using your main guns instead. Not to mention the dps of TB pistol is smaller than some other pistols or most main guns (unlike mustang or ronson)