AEA .30 breech oring size?

Hello, strangers lol!

I had the famous magazine blowup in my aea .30 challenger bill pup 32” barrel.
Only run about 100 rounds though it, and a chunk is gone when I looked at the oring.

What do y’all think I’d the absolute toughest material type to use on that?

And…. Will the metal mag lower the danger of the magazine explosion?
Or will that only direct all the force backward? lol
Scared me; felt like Tyson punched me. Thought I’d lost my eye at first

Thank you guys so much!
Y’all are a wealth of knowledge.