Unknown BB gun/pellet rifle

Hello - Wandering through an antique mall today, I noticed a BB/pellet rifle of unknown configuration. I was unable to take a photo of it, so I will describe it as best as possible. It was the length of a small rifle, like a BB rifle, with a wood buttstock. A round barrel with what appeared to be a coilspring lever underneath. The mechanism seems as such that it would load a pellet and tighten the spring at once (btw- this is a spring loaded BB gun, not air).

Most unusual was that the pellet compartment was some sort of barrel or cylindrical-shaped container, with only the word "AMMO" stamped above a small hole where presumably the pellets were loaded. No markings of any kind otherwise. The front sight was hooded, but could not tell if this was original or modified later. This BB rifle seems to be at least 50 years old, could be older.

Short of having an image of it, does this help any? Thanks for any help.