steel in 10 gauge

[hammer1]

Ladies and gents, I was given a kassnar 10 gauge 31/2 ", side by side. Its a bit of a monster, around 11 or 12 pounds. My question, could I use steel in it? Its fixed, full and full, but would like to use it for what it was designed for. Ive looked around a bit on line, and the feeling is mixed, some say theyve used steel shot in old fixed chokes with no ill effects.