I would like to have a 77/22 barrel threaded for a comp.I am unsure of the legality of this.if it is legal does anyone know where i could have this work done.

I'm not aware of any prohibition on doing so; the recently expired 'assault weapons ban' only covered doing this with semi-autos.

As always, your state laws may differ, and you might call a few local gunsmiths and see what they have to say.