This description has been copied from the NRA site:
We pretty much follow these procedures with the following exceptions ... Since we only have a 100 yard range we use different targets to simulate the extended ranges. This is explained below in “Reduced Distance” section.
Also since most of us are getting along in years, we usually start in position, such as prone or sitting instead of have to come into that position from a standing position.
High Power Rifle Competition
For additional information please call the NRA High Power Rifle Dept. at (703) 267-1479
Courses of Fire
There are 4 strings of fire which are the basic building blocks of any NRA high power rifle course of fire or tournament. These are:
1. Slow Fire, standing - 10 rounds at 200 yards in 10 minutes.
2. Rapid Fire, sitting or kneeling - 10 rounds at 200 yards in 60 seconds.
3. Rapid Fire, 10 rounds prone - 300 yards in 70 seconds.
4. Slow Fire, 10 rounds prone - 500 or 600 yards in 10 minutes.
Every NRA High Power Rifle match for which classification records are kept is a multiple or a combination of one or more of these strings. The popular National Match Course, for instance, consists of 10 rounds slow fire standing; 10 rounds rapid fire sitting or kneeling; 10 rounds rapid fire prone and 20 rounds slow fire prone. Matches fired all at one distance and in one position are known as "single-stage" matches and are usually 20 shot matches (2 times one of the basic strings).
"Slow Fire" does not require much explanation. The shooter takes his position on the firing line, assumes the prescribed position and is allowed one minute per shot to fire the string.
"Rapid Fire," on the other hand, is more elaborate. In rapid fire sitting or kneeling, the shooter uses a preparation period to establish sitting or kneeling position; then comes to a standing position and, on command, loads either 2 or 5 rounds (depending on the firearm) into the rifle. When the targets appear or the command to commence fire is given, the shooter gets into the firing position, fires the rounds in the rifle, reloads with 8 or 5 more for a total of 10 and finishes the string. The procedure for rapid fire prone differs only in the firing position and the time spent.
Rifle: Rifles to be used in High Power Rifle competition must be equipped with metallic sights (Some long range, 1000-yard matches allow the use of "any sights"), should be capable of holding at least 5 rounds of ammunition and should be adapted to rapid reloading. Tournament programs often group competitions into two divisions, Service Rifle and Match Rifle. The rifles currently defined as "Service Rifles" include the M1, M14, M16 and their commercial equivalents. Winchester and Remington have made their Model 70 and Model 40X rifles in "match" versions and custom gunsmiths have made up match rifles on many military and commercial actions. 1903 and 1903-A3 Springfield, 1917 Enfields and pre-war Winchester Model 70 sporters in .30-06 are all equipped with clip slots for rapid reloading. The most suitable rear sights are aperture or "peep" with reliable, repeatable 1/2 minute (or finer) adjustments. Front sights should be of either the post or aperture type.
Sling: The shooting sling is helpful in steadying the positions and controlling recoil. The sling may be used in any position except standing.
Spotting Scope: A spotting scope or a substitute optical device is important for scoring and observing the placement of shot spotters on the target. The beginning shooter will benefit from the use of about any telescope which gives an erect image. The most suitable spotting scopes, however, have a magnification of from 20 to 25 power and an objective lens at least 50mm in diameter. Eyepieces angled at 45 to 90 degrees are convenient for using the scope without disturbing the shooting position.
Shooting Coat: The shooting coat is equipped with elbow, shoulder and sling pads which contribute to the shooter's comfort. Since there are several styles of shooting coats of varying cost, the shooter is advised to try out several types before making an investment.
Shooting Glove: The shooting glove's primary function is to protect the forward hand from the pressure of the sling. Any heavy glove will serve the purpose until the shooter makes a final choice among several shooting gloves available.
Sight Blackener: The shooter using an exposed front sight such as the blade found on the service rifle will require some means of blackening the sight. A carbide lamp will do this job or a commercial sight black sold in spray cans can be used.
Scorebook: If the shooter is to learn from experience, they should record the conditions and circumstances involved in firing each shot. Sight settings, sling adjustments, wind and light conditions and ammunition used all have a place in the scorebook. Actual shot value is the least important data recorded.
Ammunition: Most competitors eventually turn to handloads. Careful handloading will yield ammunition less expensive and more accurate than otherwise available. Both tracer and incendiary ammunition are prohibited by NRA Rules and armor-piercing ammunition may be prohibited by local range regulations.
Long Range Competition
NRA rules provide for slow fire prone competition at ranges beyond 600 yards. The Palma Match is one such event. It is conducted at distances of 800, 900, and 1000 yards. Some of these matches permit the use of telescopic sights.
High power rifle shooting at the full regulation distances requires a range with firing lines at 200, 300 and 600 (or 500) yards.
Every official NRA stage or course of fire normally conducted at 200, 300, or 500 yards can be run at 100 yards on the NRA official reduced targets. The SR-1 target simulates the 200 yard target; the SR-21 is the 100 yard equivalent of the 300 yard target and the MR-31 gives the same appearance at 100 yards as the normal 600 yard target does at the full distance.
Because of their small size, the reduced targets are well adapted to being hung on stationary frames. Because of the short distances involved, it is practicable to walk down to the targets after each string and remove them for scoring elsewhere or to score them on the frames. The use of stationary target frames eliminates the complications that sometimes arise when the number of shooters on the line is not equal to the number of target operators in the pits.
Reduced 300 and 600 yards targets are also available for firing at 200 yards. The NRA can provide a list of target sources, including reduced targets.
High Power Sporting Rifle
The High Power Sporting Rifle Rules were introduced in 1985. This variation is fired with hunting type rifles which may be equipped with telescopic sights. The course is fired at a single distance - either 100 or 200 yards - and rapid fire strings are only 4 shots to accommodate the typical hunting rifle.