O rings under the barrels

[Bucko]

Hi folks first of many silly questions the two large "o" rings that fit under the barrel sleeves,what do they acheive?surely the gasket seals the join between cases and barrels?

 

[XSLeo]

It's just a bit more insurance against leaks. I didn't put them on my 75 and the base gasket is leak free.
Leo

 

[Bucko]

Thanks for that