I picked up a metric o-ring gauge from McMaster-Carr a little over a year ago and it has proved to be quite useful. It really takes the guess work out of sizing o-rings. Here's the gauge I bought:
https://www.mcmaster.com/9440K43/
It's not cheap ($26). However, it has always proven to be accurate. I determine the inner diameter with the gauge and use a caliper to get the thickness.
My CGA347 hand tight fill adapter o-ring started leaking yesterday during a trip to the range. It is the orange one. I was done shooting for the day so it was no big deal. These adapters usually come with spares. I measured the spare to be 7mm ID and 2 mm thickness. Some have said this o-ring is made of delrin or teflon. An AGN member a while back determined these Teflon o-rings work:
https://www.mcmaster.com/1196N73/
https://www.mcmaster.com/9440K43/
It's not cheap ($26). However, it has always proven to be accurate. I determine the inner diameter with the gauge and use a caliper to get the thickness.
My CGA347 hand tight fill adapter o-ring started leaking yesterday during a trip to the range. It is the orange one. I was done shooting for the day so it was no big deal. These adapters usually come with spares. I measured the spare to be 7mm ID and 2 mm thickness. Some have said this o-ring is made of delrin or teflon. An AGN member a while back determined these Teflon o-rings work:
https://www.mcmaster.com/1196N73/
