Scope

This Technical Note documents the mechanical and ballistic reasoning behind the 16–20 inch optimal barrel length range for straight-wall pistol-caliber cartridges used in lever-action rifles.

Key Observations

  • Peak chamber pressure occurs early in the bore
  • Acceleration is largely complete by ~14–16 inches
  • Residual pressure beyond this point contributes diminishing velocity gains

Velocity vs. Barrel Length Behavior

Empirical data across .357 Magnum and .44 Magnum platforms shows:

  • Significant velocity gain from handgun lengths to ~14 inches
  • Moderate gain from ~14–16 inches
  • Minimal gain from ~16–20 inches
  • Negligible or inconsistent gain beyond ~20 inches

Beyond 20 inches, frictional losses and pressure decay often offset any theoretical acceleration.

Recoil Impulse Timing

Barrel length influences recoil impulse duration, not just energy:

  • Short barrels produce sharper impulse
  • Mid-length barrels stretch impulse over time
  • Longer barrels increase forward mass without improving impulse quality

The 16–20 inch range produces the most controllable impulse for lever-action ergonomics.

Suppressor and Muzzle Device Considerations

Shorter barrels provide:

  • better suppressor efficiency per inch
  • improved balance with added muzzle mass
  • reduced overall system length

This reinforces the mechanical logic of modern 16–18 inch configurations.

Design Implications

This barrel length window explains:

  • historical success of carbine-length lever guns
  • modern guide gun and SBL configurations
  • why longer barrels persist mainly for legacy or aesthetic reasons

Conclusion

For straight-wall pistol-caliber lever rifles, 16–20 inches is not a compromise. It is the point of maximum efficiency dictated by internal ballistics, recoil behavior, and platform ergonomics.

Relevant Citations