HW/Weihrauch HW100 Cylinder end oring?

My cylinder ends on each end decided to blow out. The cylinder is a titanium replacement. So in my oring kits I found some orings that were too fat, but for now they seem to work, but I imaging since they are pinched, they will blow. I did a search, and NBR70 26x2mm was mentioned in a UK airgun forum. So I don't know if that is correct, so I would appreciate confirmation, and confirmation that the ebay link for the orings is correct. Only 2 bucks for 10, so that is cool if they are correct.