M-1 carbine for defence?

[Faulkner]

Personally, I don't get the purpose of the bolt hold open magazine follower for a M1 carbine. As soon as you pull the magazine out the bolt slams shut anyway.

 

[Spotteddog]

I agree.
It seems to be a feature some like though?

 

[Jack Flash]

Some people like the visual indication that the magazine has run dry and should be replaced with a full one as the situation warrants.