I felt sorry for the item.

[Sentryduty]

Here's a teaser for you Bren fiends. Do you know WHY the magazines were modified to accommodate the auxiliary spring - and late made that way...........?

I don't know the reason, but thinking logically I would guess that it might be to keep the rounds of rattling fore and aft in the magazine?

Otherwise, I can only see it acting on the follower to keep it from hanging up on the inside of the magazine body, or to tension and slow the follower perhaps preventing double feeding, if that was an issue?

I am however curious to know.