Sentries at the 2nd India Reserve Battalion (IRB) headquarters in Manipur’s Bishnupur fired 327 rounds of ammunition and burst 20 tear gas shells on Thursday in a bid to keep at bay a 500-strong mob that seemingly brooked no stopping as it targeted the armoury, looting 298 rifles, SLRs and LMGs along with mortars, grenades, and 16,000-odd rounds of assorted ammunition.