Slid on my steering boss, it's fine on the spline but doesn't seem to sit down far enough. The horn ring wasn't touching the contact. The nut also didn't go all the way on.

I know there isn't much pressure put on the nut so it should be ok, was just wondering if anyone else had a similar issue?

hammer the shit out of it to get it on or replace the boss, it could work the nut off with vibrations as its not seated correctly

The problem is the boss has a flat section at the back which is bottoming out on the cone shaped bit after the spline. Hammering would break my boss.

I've used a fair bit of thread lock on the nut so it shouldn't vibrate loose.

I've used a fair bit of thread lock on the nut so it shouldn't vibrate loose.

thats not just your problem, when you turn and put pressure on the wheel on one side it could push the boss back and work the nut loose

id change it