I have two goose calls, both Buck Gardner's. A Canada Hammer II and a Honker Hammer. They both have the same guts in them, albeit not SR1's but whatever it is that Buck puts in his calls. The Canada Hammer II is bored 5/8" and requires a pretty fair amount of hand backpressure and so on to get it to do much. The Honker Hammer on the other hand is bored 3/4" with a slight flare and it can really open up and sing without much hand movement needed. I don't know if that is really an apples to apples comparison with your call as I have not blown yours, but maybe there it something to that and that is what I plan on boring my calls.
All that aside, I think that is an excellent looking call there. Great lines and accents and looks very comfortable in the hand.
