I have always used a nonlockabel plastic case to transport my ammo to SA. I put a TSA lock on the suitcase and considered that as locked. Never had a problem with that. Now I read where the ammo has to have it's own lockable case??
Is that correct or does a locked suitcase still count??

You would think that anyone with a brain would accept your idea of a lockable case...however, we know who we are talking about here. The easiest solution is either a pistol case, or a small dry-box with a lock on either. A small tool box will work as well. I usually throw them in a small dry-box with locks which go inside another bag with locks. Its an easy fix and why chance it?

On four trips to Africa I used this MTM shotshell box with the choke tube case removed without problems. Rifle ammo fits nicely; it is very light, pretty strong, cheap served the purpose very well. I put a small keyed lock (one of those silly cable gun locks that you get with everyfirearm now) on the case and placed it inside one of our luggage (not in the gun case) and told every customs or airline agent that my ammunition was safely stored in a locked container for which only I had the key and weighed no more than the 5kg/11lbs. Never a hitch…only once in RSA did they pull it out and weigh it.
Good luck
Paul

See:MTM Shotshell Choke Tube Case