Ragged Hole Barrels sell several contours of Wilson barrels, including 6mm 1:8 for $175. Button cut, but I bought a 6.5 and it shot quite well. Call to confirm what you want is in stock.
https://raggedholebarrels.net/collections/wilson-barrels?page=2
https://raggedholebarrels.net/collections/wilson-barrels?page=2