Rick, I understand your curiosity, but does it really matter what WS1 is? You can order a choke cut to any dimension there is, within .001". What it is called (WS1, or SK1 and SK2) is way secondary to what the choke actually does.

I can attest to Dean's capabilities and work, at Skeet's Gun Shop. First rate, and you don't have to wait forever on it.

SRH

May God bless America and those who defend her.