What are the meanings of these marks on a shotgun - a crown over ELG in an oval - L with a star above - A overstamped F with a star above - a script AE - 12 G in a diamond and a tower on a pedestal?

the "elg" means made in belgium after 1893. the 12 in a diamond means 12 gauge. The script AE and tower (le Perone) are also Belgian proof marks and the AF may stand for Auguste Francotte & Co, a gunmaker established in 1849 and still in business today.