I've been sourcing all my orings off of amazon.com for air guns. A simple ring sizer (cone shaped) allows most orings to just touch the circumference allowing you to use a veneer gauge to get the od, mark the oring location on the gauge and measure the ID, the difference is the cross section or oring thickness.
I just use that info and grab the closest size to my measurements although I do have to convert measurements from imperial to metric on occasion.
I've never had one I purchased not work in that specific location I measured.
One caveat, I have opened my Diana barrel oring slots to accommodate 1mm orings simply because the .7mm orings they used were too flimsy.
I just use that info and grab the closest size to my measurements although I do have to convert measurements from imperial to metric on occasion.
I've never had one I purchased not work in that specific location I measured.
One caveat, I have opened my Diana barrel oring slots to accommodate 1mm orings simply because the .7mm orings they used were too flimsy.
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