Cartridge overall length can be tailored to a specific firearm to get the best accuracy. If your gun was made with a short throat from the manufacturer or with a long throat, or if the throat has been elongated because of wear, the cartridge OAL can be adjusted to a length that will produce the best accuracy. Even on a firearm that is perfectly in manufacturers specifications, adjusting the OAL may improve accuracy. The cartridge overall length chart supplied by the manufacturer is designed to produce safe ammunition that will fit in the magazine of most all rifles from many manufacturers. There is no way that they can factor all the variations between individual rifles. Finding the overall length that gives the best accuracy in a particular rifle can be a valuable endeavor.

The Hornady overall length gauge is used to measure the length of the chamber from the cartridge head to the rifling. Adjusting the seating depth of the bullet will change how much jump the bullet has before it engages the rifling. The OAL gauge requires the use of a modified cartridge case. The case must be drilled and tapped through the primer pocket and flash hole so that the rod of the OAL tool can be threaded into it.

Once the cartridge case has been modified, the tool can be used to measure the dimension of your chamber. This tool will use the bullet that you intend to load. Measurements can be made for whatever bullets you decide to use.

The modified case is threaded onto the rod of the gauge and a bullet is started into the case mouth. The case needs to not be resized so that the bullet can move freely. The case and gauge is then placed into the chamber and the measuring rod is moved until the bullet and rod is snug against the rifling. The rod is locked, and the gauge is removed. After The gauge is removed a set of dial or digital calipers with a comparator is used to measure the OAL. The comparator must be used because the bullet doesn’t contact the rifling on the point of the bullet.

If you are interested in finding the OAL of a particular bullet in your rifle, Craig’s Outdoor Sports can make a modified case for you. You will need a cartridge case that has been fired in your rifle, a bullet that you want to load and your rifle.

If you want to learn how much the throat of your rifle has worn and how much you should seat out the bullet, this gauge will also show that. Regulating the amount of jump of the bullet has an effect on accuracy. Knowing how far a bullet can be seated out without having a bullet stick in the rifling is important if you want to find the best seating depth for accuracy. Talk to Craig at Craig’s outdoor sports to see about getting your rifle gauged.