Air Arms s410 barrel shim

[rickg]

Hi All
I've got a s410 classic pre/ AT I'm trying to replace the breach o ring but when i took the barrel out the brass bush stayed in the gun. So after a lot of messing. I managed to get it out .So now it's out I look at the parts list to find out witch part I need & it tells me there's an external o ring so I checked but there is no recesse for it
Any help would be much appreciated.
Regards Rick

[TenMetrePeter]

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