Introduction¶

ChamberSim Reloaded calculates the interior ballistics of a handload: you choose a cartridge, a bullet and a powder, enter the powder charge, and the program simulates how the pressure, the bullet velocity and the bullet energy develop while the bullet travels through the barrel. From that it reports the maximum pressure, the muzzle velocity, the barrel time and many related values. A load development ladder, charts, reports and printouts help to plan a series of test loads.

It follows the workflow of Gordon’s Reloading Tool (GRT). It can open the original’s .grtload files and can use the original’s database, but stores its own loads in the .csrload format.

What the program can do¶

• Cartridge, projectile and propellant records from a database; replace any component of a load; add your own records.

• Pressure, energy and velocity curves with markers and pressure bands, a burn-rate chart and a load ladder.

• Drawings of the cartridge and the chamber with the C.I.P. dimensions.

• A Measurements tab for chronograph and pressure data, with statistics (mean, SD, ES) and a comparison with the simulation.

• Fit to measurements: adapts the model values of a powder to your own data.

• Reports with a template editor, print preview and PDF export.

• Metric, imperial and original units (also per field), light and dark themes, adjustable font size.

• Translations: English, German, French and Italian.

How accurate is it?¶

The default Physical Model is fitted to published load data of powder manufacturers. Against loads that were left out of the fit, the muzzle velocity is typically within 3–6 % (root mean square; Vihtavuori powders about 3 %, Hodgdon about 6 %) and the peak pressure within about 15 % where the tables publish it. The scatter of the published tables themselves (lots, barrels, components) is of that size. Single loads can deviate much more. Unusual loads, other powders and other cartridges than the ones tested can deviate more again; slow powders at low pressure, pistol and revolver cartridges (about 8 % in velocity and 19 % in pressure) and shotgun loads (about 3 % in velocity and 16 % in pressure, with their own constants) are known weak spots. Powders without physical burn values, such as your own records, are less accurate than the project’s powders. The GRT Original model reproduces the results of the original program to about 1 % in velocity and 3 % in pressure. The files README.md and docs/ACCURACY.md of the project contain the current accuracy tables.