I did similar in miniature with a Daystate Wolverine HP .30 air gun. I can only get a 50 yard distance here at the house. When I got to where I could hit 20 9/16" marbles in a row, I switched to 1/2" and when they got boring, I went down to 7/16" marbles. 7/16" is the limit of the gun and expect high levels of consistency. Not quite the same, but best I can do here at the house.