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The Filling Percentage is the effective or usable combustion chamber volume occupied by the charge. This is also also named "Load Ratio" or "Fill Rate" and can be found in good reloading manuals.

The Effective Combustion Chamber Volume is further explained here.

The volume occupied by the charge is equal to the powder bulk density multiplied by the weight of the charge. The powder bulk density can be found in our powder/propellant database.

• Fill Rate = volume occupied / usable combustion camber volume

• Volume Occupied = charge x bulk density of powder

• Usable combustion camber volume = total case volume - volume occupied by seated bullet

Important notice: Reloaders commonly try to operate with fill rates between 80% and 100%. Loads below 80% can be dangerous as they can produce very unsteady results. Loads above 100% are "press loads". They can also produce unsteady results and often dangerous pressures.

Propellant combustion is the solid-to-gas conversion of the powder. The metric "z" defines the percentage of the burnt propellant when the projectile leaves the muzzle.

When optimizing a cartridge load through appropriate selection of components, combustion preferably ends before the projectile passes the muzzle. Achieving more than 95% of burnt propellant is considered to be a fair load. This improves energy utilization, ensures consistent results and somewhat influences the generation and appearance of muzzle flash.

v or V(0) is the bullet / projectile velocity when the bullet base passes the barrel muzzle - assuming the stated barrel length. In our load tables, V(0) is calculated with a standard barrel length of 23.6'' (60cm) for rifles and with 7.09'' (18 cm) for pistols/revolver.

The Effective Combustion Chamber Volume is calculated by subtracting the volume of the portion of the bullet extending into the case from the Maximum Case Capacity. The standard Maximum Case Capacity can be found in our cartridge database and is also provided by the safety standard.

Image: Effective Combustion Chamber Volume indicated in red.

Important notice: The actual case volume can deviate significantly from the standard value. We recommend you measure your cartridges before loading.

This is how you can measure the case volume: After obtaining the weight of a dry empty case (with used primer in place), fill the case with water. Eliminate any air bubbles and bring water even to end of case neck. Reweigh water-filled case. Subtract dry case weight from water-filled case weight. This gives case capacity in grains of water, which is the standard unit of measure and listed in our database.

The volume of the portion of the bullet extending into the case needs to be calculated based on the bullet type, specifically the base type of the bullet. With flat-base bullets, calculation of the area occupied by the bullet requires only bullet diameter and seating depth. With boattail or hollow-base bullets, base design needs to be considered.

There are two safety standards for (civil) ammunition established all over the world, which every handloader should know:

In the USA, the SAAMI (Sporting Arms and Ammunition Manufacturers Institute, Inc., 555 Danbury Road, Wilton, Connecticut 06897) publishes and sponsors standards approved by the ANSI (American National Standards Institute) as voluntary industry performance standards for the use by commercial manufacturers.

The C.I.P. (Commission Internationale Permanente Pour lEpreuve des Armes à Feu portatives, 45, Rue Fond-des-Tawes, 4000 Liège, Belgium) sets the standards for civil ammunition and weapons for European member countries. These standards are mandatory in countries having ratified the CIP Standard.

By working together, the CIP and SAAMI are working towards the development of international standards. Maximum standardized pressures are listed in our cartridge database.

Notice: We recommend to stay 10-15% below the maximum standardized pressure with any load to buffer for any variations. Only very experienced handloaders should exceed these thresholds at own risk.

Seating depth refers to the distance from the base of the bullet to the mouth of the cartridge case. This measurement determines how deeply the bullet is inserted into the case and directly influences the Cartridge Overall Length (COAL). Adjusting seating depth affects the internal volume of the case, which in turn impacts chamber pressure and bullet jump—the distance a bullet travels before engaging the rifling. Precise control over seating depth is essential for achieving consistent velocities and optimal accuracy.

Shank seating depth focuses on the portion of the bullet's shank—the cylindrical section of full diameter—that is seated within the case neck. This measurement is particularly important for ensuring proper neck tension and alignment. Adequate shank engagement within the neck helps maintain bullet concentricity and can influence the bullet's release during firing. We utilizes shank seating depth to calculate usable case capacity and predict ballistic performance.