"O" rings

[Nvreloader]

Guys
I need some help,
I am attempting to figure out how measure "O" Rings, and then find the correct sizes etc.

I desperately need the "O" RINGS that fit inside these JT type adapters for the 88/90 gram prefilled Co2 cylinders,

By using the inside and outside dimensions + thickness, of the used "O" rings etc,
I have found NO, "O" rings that are even close, in/with standard "O" ring sites.

Does anyone know for sure what the correct size is?

This "O" ring must seal on the outside/against of the cylinders neck and also seal on the outside of the diameter of the "O" ring against the adapter wall/groove,
when the cylinder is screwed into the adapter and used correctly.

The diameter of the cylinder neck is .455" when starting into the "O" ring and then changes dimensions to .495"/.500" when fully seated.

I would greatly appreciate any help or info for the correct size of "O" ring.

Tia,
Don

[anti-squirrel]

I'd slip a lightly-lubed (use dive grease) metric O-ring that fits snug inside the opening.  Harbor Freight has metric O-ring packs that should have what you need, and as long as it fits snug, you're fine as it will seal.  Those 88- and 90-gram canisters have an M16x1.5 thread, so expect a metric O-ring.

[Nvreloader]

Thanks Peter

I was not thinking metric sized "O" rings,
I'll have to find a metric conversion chart to standard inch, as (I don't know metric speak), then do some researching again,
as the search dog on this site doesn't work very well.

Out of 5 adapters,
this is the last remaining working one, and I am afraid of damaging it trying to get it out,
then Leaking Lena will be out of service period.  LOL 

I was hoping that someone would drop the 411 on me,   
This conversion to the repeater breech is tuning into quite a project and learning experience,
I was hoping to have her up an running for opening day of CT season, which opens the 15th, as I need to restock the freezer......

Tia,
Don