Hey guys, in need of some help. Replaced a brake haRd line today, and have a new set of problems. Where the bolt goes into the master cylinder is leaking. the old line had a 9/16th bolt that was shortert, and the new line came with a longer 9/16th. what would cause it to leak out around the bolt? it's as tight as I can get it without rounding off that ****ty soft metal. please help me.

 

Is it because of the length of the bolt? this was all the auto part stores had in 9/16th