Why not positional variation?

[oshfdk]

Maybe they are badly written m or i+loop+downstroke, and the last image is a+loop+downstroke.

Gosh, I guess I was not paying attention. Are these usually transcribed as m? Most of them look like a sloppily written m, but some of them like ainaiŋ look very deliberate and carefully written to me.

This actually leads to the question of whether r and n are the same?