At one time, they would not return bulk load cartridges hereabouts or in my home town over 300 miles away, so I doubt if they will today. This makes things more difficult due to the difficulty buying cartridges nowdays.
Of course, when I rolled my own, I processed my own. So......
The shape of the leader is very important in todays cameras due to the autofeed capability so you might cause a bad feed and a jam at the start. It is not important in the process machine as the leader is cut off square and spliced.