I'm sorry, I don't think Hammer would want this one. All I had available for testing were some handloads I made up a couple years ago for the Swift I had. I was happy to find they fit this gun OK.

All loads are using RP brass and WLR primers and Varget.

38gr and Sierra 52 bthp was over an inch.
37gr and Sierra 52 bthp was a 4 into 3/8 (bug hole) and a flyer to make it 1/2 an inch.
38.7 and 50gr Dogtown just over 1/2 inch.
36.8 and generic 55sp (another bug hole) about 3/8. (shocker, I wish I knew what these were. I bought 500 on sale somewhere a couple years back and the box isn't marked)

It seems to open up a bit with higher pressure loads. There were a couple other loads that were over an inch. I think this really has potential. If my eyes were better and some work on my technique would help too. It was 55 degrees with light gusts of wind from right to left.