Breech Seal O ring RH93

[Galo29]

As per title, does anyone have a definitive size for the breech seal o ring on a Park RH93 .177 please?

 

[Jay.T]

Metric Standard	4.5mm ID x 1.5mm CS	FP121 / OR073
Imperial Tight-Fit	4.47mm ID x 1.78mm CS	BS008

the only info i can find.

 

[Galo29]

Metric Standard	4.5mm ID x 1.5mm CS	FP121 / OR073
Imperial Tight-Fit	4.47mm ID x 1.78mm CS	BS008

the only info i can find.

Thanks but they're a lot smaller than that. Got one from John Knibbs 5mm OD 2mm ID but it's leaking air.