When I put an A&B barrel on an XL7, I set headspace and tightened the barrel, then I rechecked headspace by placing 0.001" shim stock under the gauge, one shim and bolt closing was possible but had to force, 2 shims no close . since it was spacing out the gauge, I knew it wasn't hitting the bolt head.
I recognize though, it may be different with the short action XS7.
