I talked to several(4) tube makers about Hevi shot at a dealer trade show.
Every one ( Comp-n-choke was not there) said Hevi shot can scratch the tubes .
The no Hevi shot warning is to cover their @ss
But when ask what they shot 3 of 4 said Hevi shot and number 4 would not give a straight anser.
Another thing if you go to Cabelas they have metal targets shot with Hevi shot and NON Hevi shot aproved tubes on display ( or did in Dundee)

Johnch