What is a cannelured bullet

In cartridges, the cannelure is a band pressed into the case which helps prevents cartridge setback when the case mouth is properly crimped onto the cannelure. Bullet setback of . 1″ can increase pressure beyond safe limits and possibly cause a catastrophic failure.

Definition of cannelure

1 : a groove running lengthwise on the surface of a cylinder or column. 2a : a groove around the cylinder of an elongated bullet for small arms to contain a lubricant. b : a groove around a bullet into which the edge of the cartridge case is crimped.

It must be clearly understood that a cannelure is essential to obtain good results with a roll crimp. Remember, bullets that do not have a cannelure but need to be crimped should be given a taper crimp. Taper crimping is the best choice for any firearm which headspaces on the case mouth.

While the term “ogive” is often used to describe the particular point on the bullet where the curve reaches full bullet diameter, in fact the “ogive” properly refers to the entire curve of the bullet from the tip to the full-diameter straight section — the shank.

Rifling: The spiral grooves cut or swaged inside a gun barrel that gives the bullet a spinning motion. The metal between the grooves is called a “land”.

For most of us, bullet setback occurs when the nose of a cartridge strikes the barrel’s feed ramp, or another internal part, while the round is chambered. … This is potentially dangerous because it reduces the cartridge’s internal case volume, producing higher than normal pressure when the round is fired.

COAL is the cartridge over all length, a vital part of reloading. if the COAL is wrong, pressures can rise to unsafe levels in some instances. Loss of accuracy is another major problem. Determining COAL is about finding the optimum length for hand loads, for your rifle.

But what is an ogive profile? Simply defined, it’s the curved portion of a bullet forward of the bearing surface. Because a flat cylinder is undesirable for exterior ballistic reasons, rifle bullets have on of three ogives or “point profiles”: flat nose (FN), round nose (RN) or pointed (spitzer).

Definition of ogive

1a : a diagonal arch or rib across a Gothic vault. b : a pointed arch. 2 : a graph of a cumulative distribution function or a cumulative frequency distribution.

Most bullets shoot most accurately when seated to within .035 inch to .015 inch of touching the lands. Many benchrest shooters like them just kissing the lands.

Cartridge overall length, or “COL”, is important to safe functioning of reloads in firearms. … This allows for the cartridge to be longer than the standardized 2.260″ SAAMI maximum overall length. These cartridges can be safely loaded to a length that has the ogive portion of the bullet just touching the rifle’s lands.

BC stands for Ballistic Coefficient

Ballistic Coefficient (BC) is a measure of external ballistic performance for bullets. The higher a bullets BC is, the less drop, and wind deflection it will have at all ranges for a given muzzle velocity and environment.

Seating a bullet against the rifling causes pressures to be elevated noticeably higher than if the bullet were seated just a few thousandths of an inch off the rifling. … Many times the best seating depth is with the bullet touching or very near the rifling.

If headspace is left too short it is most likely that a cartridge will fail to feed into battery properly. With most modern rifle designs this will render the firearm inoperable (not all designs require a firearm to go all the way into battery before allowing the firing pin to release and strike the primer).

Jump is the distance away from the lands of the rifling and Jam is distance into the rifling that you are forcing the bullet when you chamber a round by closing your bolt.

Myth 3: High-BC bullets are inherently most accurate.

When a bullet slows below supersonic velocities (lower than about 1100 fps), accuracy deteriorates considerably. This occurs with low-BC bullets at much shorter ranges. High-BC bullets are more accurate, but only at longer ranges.

For many reloaders, annealing is a “dark science” that defies easy explanation. When done right, annealing extends brass life and makes neck tension more consistent, something very important for accuracy. … And we know annealing can make your brass shoot better and last longer.

In firearms, freebore (also free-bore, free bore, or throat) is the portion of the gun barrel between the chamber and the rifled section of the barrel bore. The freebore is located just forward of the chamber neck and is cylindrical in shape.