Didn't get a chance to stop by Grainger work has been hectic but I did manage to take one magazine apart to get you a measurement on the o-ring in metric.
22mm by 1.5 mm or 22x1.5mms.
If you type in 22x1.5mm o-ring for ebay the search return several options to choose from. The price range from 3.00 -10.00 I believe.
I hope this helps.