You have the rifle in hand.
Show us pictures so we can be sure what you have and the discussion can go from there.
Probably an importers stock number and the country of origin as required since 1903.
a crown, then a "R"
Belgian proof mark for a firearm with rifled barrel.
crowned balloon in which there's "E" and 'LG" under the "E".
Long time standard Belgian proof mark.
found a "MG" mark
Don't know offhand, maybe a factory inspector's mark.
"FL 22 L"
I don't know for sure but suspect it stands for Flobert (design) and .22 Long cartridge. That is where YOUR pictures come in.
Lacking pictures, I can only guess.
It sounds like a Warnant action Flobert and if so, it is NOT supposed to kick open and blow the empty out. Of course it might be something else made to operate that way. I once had a very obscure single shot "automatic" like that.