What is ApexLOAD PRO?

What is ApexLOAD PRO?

ApexLOAD PRO is an internal ballistics software (sometimes called an internal ballistics tool) used by reloaders and shooters to develop load recipes by predicting how ammunition behaves before firing a shot.

It models key internal ballistic variables such as: chamber pressure, powder burn behavior, and muzzle velocity.

Many modern tools (including ApexLOAD PRO) can also calculate external ballistic outputs such as trajectory, bullet drop, and wind drift.

By modeling these variables digitally, reloaders can develop safer, more consistent, and more precise loads, while reducing trial-and-error at the range.

How does ballistics software work?

Ballistics software uses mathematical and physical models to simulate powder combustion, pressure buildup, and bullet acceleration inside the barrel. Users input cartridge, bullet, powder, and firearm parameters, and the software processes these inputs using calibrated models and databases.

The result is an estimate of pressure curves, velocity, and—when supported—external trajectory, helping users evaluate load changes before real-world testing.

What ballistics tools are available?

Today, the three most relevant internal ballistics tools for reloaders are:

• Gordon’s Reloading Tool (GRT) 
• QuickLoad (classic legacy software) 
• ApexLOAD PRO (modern successor platform)

For a detailed breakdown, see our side-by-side comparison of the three options.

Why should I use a ballistics calculator?

Most published reloading data comes from bullet manufacturers and powder manufacturers. These data sources usually provide starting and maximum loads, plus pressure and velocity values based on a fixed test setup.

However, traditional load data is often limited because it:

• primarily covers the manufacturer’s own components 
• assumes specific defaults (e.g., COAL, barrel length, case capacity) 
• rarely covers recipe variants where your parameters differ from the published setup

Where ballistics calculators are stronger. Ballistics calculators allow you to explore load recipes across millions of combinations of:

• calibers 
• bullets 
• powders 
• seating depths 
• case capacities 
• barrel lengths

This makes it easier to estimate performance for your rifle and your components, not only the “default” test setup.

Why ApexLOAD PRO is especially powerful

ApexLOAD PRO goes beyond basic simulation by helping users find better load combinations faster using advanced tools such as:

• PPS (Parametric Powder Search): compare powders that match your criteria (velocity, pressure limits, efficiency, etc.) 
• OBT (Optimal Barrel Time): a sophisticated method to identify charge-weight “sweet spots” for a given rifle