I shoot under [I believe] older ISSF rules (from when they were the ISU). Our range is a 20 yard range and we don’t have the length to accomodate the 25m discipline. A place to find out about shooting these types of events can be found here under the Technical rules for all disciplines and technical rules for pistol.
As a quick primer: the X-ring on an 20yd ISU #73 target is covered by a dime. My first time out I put two rounds through that (and it is an extremely good day when I can put one out of ten in that area), The next ring is the 10-ring, which is slightly smaller that 2 dime diameters. I had one round just nick the line and another just outside. The remaining rings are about a penny’s width outside the preceding ring. the 7 ring inward are black and our pistols are sighted for 6 o’clock or sub 6 o’clock hold for these targets at 20 yds. 6 o’clock means that the front and rear sights are levelled and the black dot of the target just touches the line formed by the sights. Sub 6 hold means that the sights are levelled as above but there is a space between the line of the sights. That space is equal in size to that between each side of the front sight in the notch of the rear sight.
The Slow Fire portion of a standard pistol match is 4x5 shots in 4x150 seconds (10 shots in 5 minutes for a half match like we shoot). The Timed Fire portion of the match is 4x5 shots in 4x20 seconds (10 shots in 40 seconds with time to reload between strings of five. The Rapid Fire portion is 4x5 shots in 4x10 seconds.
In the league I shoot in we follow that up with a half match of Sport Pistol which is another 30 shots total. The first fifteen are shot in the Precision portion: 15 shots in fifteen minutes. The next fifteen are shot in the Sport Rapid or Duello fashion (on different targets (10 ring is 3 quarters across, each subsequent ring is larger by a canadian two dollar coin, out to a minimum ring of 5 points, all shots outside the 5 ring score 0 points, the target is all black, so 6 oclock hold isn’t as helpful here, adjustable sights like that on high end target pistols like Pardini’s which can be adjusted to centerhold with a certain number of clicks are an advantage here). The duel portion requires the shooter to hold the pistol and his/her shooting arm down at a 45 degree angle until the target faces. At that point the shooter must raise and fire one shot before the target edges (3 seconds). After the shot s/he returns to 45 degrees to wait 7 seconds before the next shot. We do fifteen shots in this fashion.
I don’t know if that clears some of that up but I don’t have a ruler on hand to give precise measures of the target but someone who shoots a 70 score on a standard target at 20 yards is typically putting all of his or her shots into a 6 inch circle.