Wikipedia
Down-the-line (DTL) clay pigeon shooting is a variation of trap shooting which is very popular in Australia, New Zealand, South Africa, Zimbabwe, Canada, France the United Kingdom and Ireland.
Its origins are from the now banned pigeon shooting and the very beginnings of the clay target sort. DTL now forms part of the family of trap disciplines and in number of competitors is undoubtedly the largest variant, especially in the Commonwealth countries where it is most popular. Competitors use a double barrelled shotgun, usually 'under-and-over' type, and are allowed to fire both barrels at a single target released on the traditional call of 'Pull!'. The maximum load permitted is 28g per cartridge, slightly larger than the Olympic disciplines which use a standard 24g load.
The traditional DTL shooting layout is set up with 5 stands in a crescent shape 16 yards from a traphouse, which throws a random target from an oscillating trap between 0 and 22.5 degrees to either side of a center post, set 50–55 yards from the traphouse. The clay should always be on a common trajectory for height, even though it is variable in horizontal angle. The average speed for a down the line clay target leaving the traphouse is usually 42mph +/- 1mph.
A normal competition would have the competitor shooting at 100 targets in total in a day. This would be built up of 25 targets at 4 different layouts (traps) with 5 targets shot on each stand rotating on a 1 > 2 >>> 5 basis, hence 100 targets total.
The scoring of points is 3 points for first barrel kill, 2 points for a second barrel kill, 0 points for a lost target. A perfect score is therefore 100 targets 'killed' with the first barrel, total 300 points. The 100/300 is a real achievement, the 4 minute mile or the 147 break of the trap shooter.
Scores are expressed with number of kills followed by number of points e.g. 98/292 would mean 2 birds missed completely and a total of 8 points dropped due to having second barreled 2 including missing 2. Competitions are decided only by points, so this score would beat a 100/291.
The competition is shot in 'squads' of a maximum of 5 shooters occupying the 5 standswhich are also called pegs. These squads are not usually teams as such, but groups of individual shooters shooting in turn i.e. Competitor 1 on peg 1 shoots 1 target; then competitor 2 on peg 2; etc. until each has shot 5 targets from each peg. They then move one peg to the right before shooting a further 5 shots in turn from that peg and so on until 5 shots have been taken from all 5 pegs, the 25 targets on that layout (aka trap).
DTL is perhaps the 'easier' single shot to make of any clay shooting discipline, but the result is an incredibly high standard of competition. Even a small club shoot will see almost perfect scores posted by the better shots, so concentration and mental strength are the real talents displayed by competitors.
Most governing bodies record their members scores from every registered competition and then grade the competitors into classes, similar to a golf handicap. These classes are AA (nominally the elite shooters), A (expert), B (intermediate) and C (novice). Prizes are awarded in each class so competitors are shooting both for the overall 'HIGH GUN' (HG) and against their peers in their respective class. Averages are reassessed periodically (every six months in the UK for example) and shooters re-classified according to form.
There are further demarkations for Juniors, Colts, Ladies, Vets (60+) and Super Vets(65+), who will also be competing for HG and class honours. There are often further classes for disabled or wheelchair bound competitors. For major international events or Inter-County (IC) championships, teams representing each country or county may be formed.
The sport is very inclusive - a novice shooter can find themselves on a squad alongside a World Champion, his wife, grandfather and grandson competing on equal terms. Competitors come from every walk of life and as entry to a typical club competition is on average around £30 and cartridges for an event perhaps the same again, the cost of competition is modest. It is certainly not the preserve of the wealthy.
Most shooting grounds will offer trial lessons and experience days.
Other variations are double rise DR, single barrel SB, automatic ball trap ABT, and handicap by distance HPD.
The Governing Bodies in the UK and Ireland are the Clay Pigeon Shooting Association (CPSA; England), Irish Clay Pigeon Shooting Association (IPSCA), Ulster Clay Pigeon Shooting Association (UCPSA; Northern Ireland), Scottish Clay Target Association (SCTA) and Welsh Clay Target Shooting Association (WCTSA).