The easiest way to check a rifle's twist rate is to use a tight fitting cleaning patch, a cleaning rod, a magic marker, and a piece of masking tape.

Insert the rod with the tight patch into the bore a few inches. Wrap a piece of tape around the rod and fold it so it makes a small "flag". Mark the rod at the entrance of the chamber guide, and note the position of the flag. Then push the rod into the bore slowly until the flag has made one complete turn. Again, mark the rod with the marker at the entrance of the guide. Push the patch out of the bore, then pull the rod out and measure between the marks. You can also usually google your rifle model number and typically find the twist rate it was designed with. Occasionally (rarely), the barrel will be stamped with it's twist rate, but this isn't always accurate.

As far as rifling rates for different cartridges go, there is a fairly simple way to calculate the necessary twist rate to match a caliber, bullet weight, and muzzle velocity. Google "Greenhill formula" or "Greenhill twist calculator" and you'll find a ton of information. Basically, the heavier a bullet is for a given cartridge, the slower the muzzle velocity will be, and the faster twist it will need to stabilize. For example, a 40grn bullet in a .223 Rem at 3500fps will stabilize in a 1 in 10twist, while match barrels, that are designed to use 70grn bullets at 3000-3100fps will require a 1 in 7.5" to 1 in 8" twist for maximum stability. The faster a bullet's muzzle velocity, the faster it will spin (rpm) for a given twist rate. Alternatively, the faster the twist rate, the faster a bullet will spin for a given muzzle velocity.

Here are a few formula's, just to get you rolling....

rpm (revs per min) = muzzle velocity (fps) * rifling twist rate (turns per inch) * 12"/ft * 60sec/min

Greenhill twist: twist rate required for a bullet with muzzle velocity below 2,800 fps: twist rate = (150 * D^2)/L * sqrt(SG/10.9)

For muzzle velocities over 2,800fps: twist rate = (180 * D^2)/L * sqrt(SG/10.9)

where D is bullet diameter in inches, L is bullet length in inches, SG is specific gravity of the bullet, which is approx 10.9 for lead core bullets (this term cancels out for lead core bullets). Specific gravity can be determined by measuring the volume of the bullet by dropping it into a graduated cylinder, and determining the actual mass by weighing the bullet. In general, 10.9 works pretty well.

Rifling rates are just the tip of the iceberg for the science behind ballistic behavior. One of the chaptes in my older version of a speer reloading manual is titled "why ballisticians go grey"... This is definitely NOT a joke...

Have fun with it...