Ok to shoot steel thru Rem LT-20?

[ulflyer]

My LT-20 is dated 1984 but has a 21" slug barrel, undated. Any reason to
be concerned about shooting steel shot thru it?

 

[FITASC]

Is it a rifled slug barrel or a smoothbore slug barrel? Do you know what choke it is?

 

[ulflyer]

Improved Cyl, smooth bore.