Gunsmithing quick Surgeon action thread question

18Echo

Sergeant
Full Member
Minuteman
Jun 12, 2007
875
158
Maricopa Co., AZ
I'm having a switch barrel rig made with a Surgeon 1086R and wanted to know what the thread size is that will be cut onto the barrel? I want to order some thread caps from Sinclair Int'l for the barrels. Thanks.