Unknown flares

Recently, I acquired these two flares. Caliber 4, no headstamps, non-magnetic. Can somebody situate them? Length is 86,1 and 78,2 cm. The ring shown on the pictures was on the brass one, pressed against the rim. It seems it’s been hand-made as it shows clear filingtracks.

I think the black carton flare could be belgian WW1.
The brass one could also be belgian interbellum??
To be confirmed.