All handguns must be single-action, meaning the hammer must be manually cocked before each shot is fired.
Stages are always different, each typically requiring 10 revolver rounds, nine or 10 rifle rounds, and two to eight shotgun rounds.
Targets are usually steel plates that ring when hit. Reactive targets, such as steel knockdown plates or clay birds, are also used.
Misses add 5 seconds to the competitor's time. Safety violations and other procedural violations add 10 seconds.
In June, Mr Innes, a former South Island and national champion, competed in the End of Trail World Championship of Cowboy Action Shooting in Edgewood, New Mexico.
Shooting in the duellist category (unaided, right-handed shooting), he finished sixth and 199th overall.
Before the world championship, he won the duellist category at four other events - two in Colorado, one in Utah and the Wyoming state championships.
His sixth-place finish at Edgewood was the one he was most proud of.
''I shot my best there ... it was four places up on last time and in the top 200, so it was good. It gives me more to work on.''
Mr Innes practises with his rifle, a reproduction of an 1873 lever-action Winchester, and 12-gauge shotgun at his home inland from Omarama, and with his .357 Ruger vaquero pistols at the Central Otago Pistol Club.
He was introduced to the sport about six years ago while visiting the West Coast.
''There's a shooting place over there and we thought we'd go and have a look. The guy in charge was a cowboy action shooter and we ended up having a go with a couple of revolvers. We thought 'that's pretty cool' ... it pretty much went from there, really.''
Mr Innes, who crafts his own leather holsters, hoped to return to Edgewood in two years' time.
''I'm not giving up on it until I take the title,'' he said.
daniel.birchfield@odt.co.nz