Large Scale Central

Why outside frame boxcars?

,
I built four outside frame boxcars in 1:20.3 scale from GR plans and a friend who is the editor/publisher of Narrow Gauge Downunder mag wants me to do a construction article on them for him. And he wants to know “Why outside frames?”
But I don’t know why the 1:1 railways built outside frame instead of the usual inside frame rolling stock.
Any accurate or reasonably intelligible answers would help.
Was it to prevent the inside framing from damaging goods stowed?
He is a reasonable guy and has given me a whole 48 hours to produce the article. To paraphrase princess Leia “Help me, LSC gurus! You’re my only hope!”
Best regards,
Phil Creer
The Toenail Ridge Shortline
Adelaide, Sth Australia
http://www.trainweb.org/toenailridge