Anyone has experience with Blaser R8?

[Paul Homsy]

Nice, what calibre. As above a 5mm hex key should work (works for R93)

I understand that one of the changes Blaser effectuated from the R93 to the R8 is going from a 4mm hex key for the R93 to a 5mm hex key for the R8 to fasten the barrels. The 5mm would be too large for the R93.