I am in the process of buying a Model 21 skeet in 12 gauge. Interestingly, both barrels are marked SK1. All the M21 skeet guns that I have seen have have been choked SK1 and SK2.
So, how common is it to have both barrels marked SK1? From a skeet shooting perspective, it is advantageous to have both barrels SK1 as it provides a more open choke. For upland bird hunting, and sporting clays shooting, the SK2 provides a tighter pattern which helps with a more distant target.
I look forward to your replies.
Bill
