I thought the forends on Model 24's were of the spring loaded snap on variety.
The forend iron in pic #2 is identical to the iron on a Model 37 28 gauge, different than all the other Model 37 gauges.
Complete forend disassembly required to remove forend and barrels.

Did you happen to notice the checkered stock?
I've not seen a model 24 with checkered wood either.

A mystery for sure.