I need a quality set of 30 mm low rings,,I cant find any of any kind,,

I have a 4.5-14 Leupold LR/T with 30mm tube and 40mm lens,it is mounted in Burris XTR mediums and is at least 1/4 inch too high to suit me,

does anybody know of a company that sells 30mm low rings,to fit a Picitiny rail??
gun junky