To get sufficient purchase on the allen screw holding the sling swivel you need to use a flexible bit holder. You can get this cheaply at any hardware store and here’s one we found on Amazon: flexible bit holder for Blaser
To get sufficient purchase on the allen screw holding the sling swivel you need to use a flexible bit holder. You can get this cheaply at any hardware store and here’s one we found on Amazon: flexible bit holder for Blaser