Need breech oring dim for Armada

[RedHeadMechanic]

Bought a new Lothar Walther barrel for my and I am having a friend who owns a machine shop fit my new barrel to my Benjamin Armada. I measured my old barrel and drafted up some plans. But I want to double check the breech oring slot dimensions.

Thanks in advanced!

Red

 

 

[T3PRanch]

I use an 010 size urethane o-ring in my .25's. The O-Ring Store model # UC70010-RED