I would like to have the barrel swapped on my PTR 91. What is involved? Who is recommended for this work? Any idea on coast? What parts are required beside a barrel? When I send it out I also plan on getting a paddle magazine release installed at the same time.

To remove the barrel you have to remove a pin and press the barrel out of the trunion. New barrel install is the reverse process. It's not something I'd recommend doing yourself, you can easily destroy the receiver when you press the new barrel in if it's not supported properly.

I'd recommend Jeff Walters at PCS or Jayson Cotter at IGF

It may be cheaper to just get a new PTR from Atlantic unless you are trying to do something very specific or have a state-level issue with purchasing a new one.

Barrel swaps aren't cheap and the paddle mag release install costs some dollars too.  New PTRs have the lighter weight G3 barrel, 5/8 threads, and the paddle release.  I can only imagine you have an early PTR with the heavy barrel and unthreaded barrel.

Findsman is right.

A barrel swap on a PTR is pretty much a waste of money.

If you have the old PTR91 with the heavy unthreaded barrel I would keep it the way it is.  Some of those first ones were more accurate than the later ones.

If you pester Morgan at Class 3 Machining, he can thread the barrel without removing it from the receiver.  It's the route I went to get 5/8x24 threads on mine.