Well I will start
with what I enjoy Rimfire Benchrest and Centerfire Benchrest.
Rimfire Benchrest is usually shot for score at 50 yards. Now different rimfire groups have slightly different targets and rules but basically it is the same. There are 25 bulls to the target and 1 shot is fired at each bull. There are sighter targets as well where one could shoot sighters to check the wind conditions. Highest score achieveable on a target is 250 25X. A X is given when you cut completely the center dot or circle of the bull so that would score as a 10X. (there is a 10 ring with a smaller dot or circle in the center of it)
The equipment to be VERY competitive in this sport is custom put together rifles. Majority of shooters build there guns from the ground up using all aftermarket components. Hall, Kelby, Turbo actions to name a few. Barrels like Lilja and Benchmark which appear to be the choice lately. Jewell 1.5 oz triggers. Numerous Benchrest stocks by the many stock makers around. Optics are usually a 36 or 45 fixed power.
There are those that shoot factory produced actions buy Suhl, Anschutz, Remington 40X, or Winchester 52D. They change the barrels, put a tuner on it, aftermarket triggers, and put a benchrest stock under it and away they go. The build has to meet the specifications of the sanctioning body.
There are weight classes. Sporter where the gun and scope must weigh in at under 7.5 lbs, 10.5 lb class, and 13.5 lb class.
Sporter rifles cannot have a stock wider than 2.25 inches in the front. Must be able to be shot from the shoulder. Scope power cannot exceed 6.5X. It has to be a repeater, wood stock, and have a safety top name a few things.
The 10.5 and 13.5 guns are the same except for weight. Stock can be 3 inches wide at the end and it as well must be able to be fired from the shoulder.
This is a brief low down on Rimfire Benchrest.
Centerfire is similar in that it has weight classes. They are uaually shot at 100 and 200 yards. They are shot for group and or score depending on the match.
There are those that prefer group shoots and those that like the score shoots. Score shooting is like the rimfire score shoots. Very similar.
Groups matches are shot at a single bull with a sighter target for checking conditions. 5 shots must be shot at the record bull for group size. This is done for 5 targets. The average group size is taken from the 5 targets and that is your aggregate for that yardage. This goes for Sporter class (10.5 lb gun), Light Varmint (10.5 lb gun), and Heavy Varmint (13.5 lb gun)
The only way to be competitive in this game is with a strictly aftermarket build. A factory action reworked and barrel installed, trigger, stock WILL NOT compete with a full blown aftermarket gun. For local club shoots a reworked may be just fine but to play with the big dogs the real deal is required. The tolerences in a aftermarket action like a BAT, Kelby, Stiller, Hall are so much tighter.
The handsdown winner for caliber is the 6PPC in group. Bullets used are aftermarket as well and run any where between 66-69 grains. In score it is starting to be a toss up between the 6PPC and the 30 BR. The 30's use bullets in the 115-120 grain mark. The 30BR also appears to be easier to tune and from what I gather when a load is found that load is basically the load all the time. The 6PPC needs to be tweeked a little more depending on temp and humidity.
Out to 600 yards the 6BR is a great caliber and holds its own. It is easy on barrels and mild recoil make it a pleasure to shoot. They only time a larger caliber really benefits is in the nasty winds.
So I hope this helps a bit on the Benchrest side of shooting. The different organizations have slightly different rules but the bottom line is the equipment stays basically the same.
Here is a pic of my BAT actioned 6PPC which I just had built about 1 month ago. Components are:
BAT Machine action which has a right bolt, left loading port, and right eject port.
BAT Machine rings and trigger guard
Robertson Composites SG&Y Benchrest stock
Jewell trigger
Weaver 36X scope
Gaillard 13.5 twist 4 groove barrel at 22"
Rimfire Benchrest rifles will look basically the same except for the fact that most use a adjustable tuner at the end of the barrel for fine tuning there ammo.
Calvin