could be protection for the targets......back when I shot silhouettes(at RBGC in Duluth)1978/1980...I used SV...I do not remember if it was a "rule".....if you know your drop, it's no difference than it would be for higher velocity, as they all drop...I'm kind of getting pumped up to shoot this...
I started shooting competitive trap in 1966....I was 13....shot some prior to that, don't pass on shotgun shooting, it's fun, and can be enjoyed by all. There are shotguns that can be fitted to him, like they were to me....no big deal....shooting moving targets is fun!!!