If you don;t ask questions you don't known now do you? No worries.
Were it me I'd put a bit of modeling clay or the lie in the socket on the master cylinder - shove it straight into place, then pull it back and check the thickness of the clay. Clean it off afterwards, of course. This will give you an idea if you have any clearance at all.
Barring that, just turn it back(away from the master) a turn or two, then try the brakes again. It's likely a real margins situation if this is the problem - a little extra clearance is going to sort it.