On a Marlin 336 what is the purpose of the rear sight folding down?

[AAM]

On a Marlin 336 what is the purpose of the rear sight folding down?

[Edward J. Palumbo]

To clear the objective bell of a scope that you may put on the receivwer, should that be necessary.

[Ontario Honker Hunter]

As a "saddle gun" it will slip into and out of the scabbard without snagging if the rear sight is folded flat. Often found in association with a hooded front sight for the same reason. Doesn't look as "westernish" as a buckhorn model with adjusting ramp, but the folding leaf works just fine.

[AAM]

Thanks. Thats what I figured but I just want to make sure.

[RJ Arena]

You might want to install a Skinner peep sight, very nice!