The end cap is preferably formed of a relatively high durometer material with an inner surface on an outer surface of the shaft and on an outer surface of the balloon skirt section, and contacts a compression member on the balloon outer surface. The configuration prevents or inhibits failure at the balloon seals which otherwise results from the compression member moving or the balloon pulling off the shaft and out from under the compression member during inflation of the balloon. As a result, the balloon catheter of the invention has an improved consistent burst pressure and/or failure mode.