MEU mag fill-in oring
 

I've got 3 Wilson Combat type (MEU) mags, and with the 3, the "outside oring" of the fill-in valve bursted out during a gaz refill. Two of these mags did that while being brand new, for their first refill.

So two questions:
-Can I find orings of that size at a "standard" hardware store (or any other without buying new valves or mags)?

-Is there anything I can do to ensure it does not happen again?

I'm using propane with the metal Madbull XG02 adapter (with integrated silicon oil reservoir).

Thanks!

So, as some PM'ed me about it, I bought refillable lighters to use their o'rings. Indeed, they are the same size. Problem solved!

After more than 4 or 5 orings blown out (my first replacement ones vanished at the first refill, too), I'm still looking for a way to ensure that they stay in place. Any idea?