Re: Somebody could help me to identify old gun belgium ELG
That is the type of revolver called the "Montenegrin" revolver. Supposedly, the King of the small Balkan country of Montenegro decreed that all his male subjects had to arm themselves with large caliber revolvers of the type made by Gasser in Austria. (Need I say that the King reportedly had an "arrangement" with the company?)
In any event, other companies, mainly in Belgium, got into the act and turned out large caliber revolvers of that type for sale in Montenegro and elsewhere. As might be expected, there was a lot of variety, but guns nearly identical to yours are shown in the Adolf Frank catalog of 1911, selling for about 14 marks, which would have been about $3.50 at the time (a Colt Bisley sold for 118 marks or about $29.50).
Current value is around $75, maybe $100 as a novelty. The actual caliber is probably 11.75mm. Ammunition is not available and experimenting with reworked rounds is not (IMHO) advisable. Parts are also not available.