I'll bet you gun-owing American Muslims didn't tell the truth in the survey.
From the story here, which tells you more statistics about guns and religion than you'll ever want to know:
The 41 percent of white evangelicals that own a gun surpasses the 33 percent of white mainliners, the 32 percent of the religiously unaffiliated (or “nones”), the 29 percent of black Protestants (two-thirds of whom identify as evangelical, according to Pew), and the 24 percent of Catholics who own one also. (By comparison, 30 percent of all American adults report owning a gun.)
