But playing with the wind, Dragons produced a lively start with outside centre Paul Emerick showing a clean pair of heels to the Munster midfield early on and out-half Aled Thomas finding good position with the boot.
They had an opportunity to go in front when they were awarded a 10th minute penalty but Thomas was wide from forty metres and although John O'Sullivan and Alan Quinlan made good ground down the standside from the restart, Munster coughed up possession and Thomas once again pinned them back into their own 22.
Munster were reduced to 14 when Marcus Horan was yellow-carded for a fairly innocuous slap but once again Thomas was wide with his effort and after Barry Murphy, Lifeimi Mafi and Ian Dowling had made the hard yards Mick O'Driscoll knocked on as he drove for the line.
Eventually we had the game's opening score when O'Gara landed a 30 metre penalty after Dragons had been penalised for a high tackle.
Munster once again lost possession inside the Dragons 22 and Aled Brew hacked down the length of the field, outstripped the Munster cover and was unfortunate that his last kick sent the ball over the deadball line.
Moments later, Brew once again threatened when he almost latched onto a kick ahead but could not manage to gather but they did get their try when Thomas scored after Munster had spilled the ball.
The second half started with a deserved yellow card for Jamie Ringer who floored Alan Quinlan and from the resultant penalty Munster established a foothold in the Dragons 22. A further penalty earned them a five metre lineout and when Michael Owen took out O'Driscoll in the air, he too found himself sitting beside Ringer in the bin.
Not surprisingly Munster opted for a scrum from that penalty, drove the reduced Dragons back and Quinlan looked to have scored a perfectly good try but was whistled for a knock-on by referee Andrew MacPherson.
Munster eventually made the numbers tell Leamy driven over in the 55th minute. Although Dragons were restored to full strength Munster began to dominate and Leamy extended their lead at the start of the final quarter with a try off a Munster put-in.
Munster: C Cullen; I Dowling, B Murphy, L Mafi, B Carney (M Lawlor 37 min) (B O'Meara 75 min); R O'Gara, T O'Leary; M Horan (F Pucciariello 61 min), F Sheahan, J Hayes; D O'Callaghan (D Wallace 58 min), M O'Driscoll; A Quinlan, J O'Sullivan (F Pucciariello), D Leamy .
Newport-Gwent Dragons: Martin Thomas; Richard Fussell, Paul Emerick, Phil Dollman, Aled Brew; Aled Thomas, Alex Walker; Adam Black, Ben Daly, Rhys Thomas; Andy Hall, Peter Sidoli; Joe Bearman, Jamie Ringer, Michael Owen capt.