I'm using the same holw saw I have has for eight years the trick is to use cutting oil and not force it. Remember adjust the drill bit no further than 1/8 of an inch above the holesaw or you wil break it. Those drums are fairly thin so no need for a massive drill but I would buy a quality one with plenty of torque and it will last you for years.
Slappin that bass like some delerious funky preist!!!
UDS, Half Pint (Mini UDS), Weber, ProQ 20, Kegrilla
*250 gallon cooker- 'The Meat Beast!!'*
British BBQ Championships
Grand Champion 2008
British BBQ Society - Southern Championship
Grand Champions 2009