There have now been 5 Grand Musters shot with Milspec Battle rifles. Of these 5, 3 have been won with large bore single shots. 2 with a small bore repeater. Once with Black Powder. Trapdoor, Rolling block, Martini-Henry and Krag. .30, .45, and .50 caliber.
Winning handguns have been a British top break, (Both Enfield and Webley pattern I believe) Colt SAA, Colt DA, Schofield, and a Remington Cartidge conversion. .476, .45s and .38s.
The 2011 Grand Muster was won with a .50-70 and a .45 after 2 years of .30 US and .38 LC.
No clear pattern or preference has yet to emerge. Krags and Trapdoors seem to be the most common on the line, (We are US based after all) but Mausers, Lees, Rolling blocks, Sharps, Spencers, Mosins, Martini-Henry and a Lebel have all made appearances.
And some others I'm sure.
Interesting. And a great deal of fun to watch.