Summary

During chronograph testing of .44 Magnum loads fired from a 16.1″ Marlin 1894 SBL, consistent evidence of incomplete powder burn was observed. Measured velocities were substantially lower than published load data, accompanied by visible unburned powder residue. The behavior appears tied to powder burn rate selection relative to barrel length rather than charge weight alone.

This report documents the observation and places it within the mechanical realities of short-barrel lever-action rifles firing traditionally handgun-oriented cartridges.

Test Context

  • Platform: Marlin 1894 SBL
  • Barrel Length: 16.1″
  • Caliber: .44 Magnum
  • Powder Tested: IMR 4227
  • Bullet: 240-grain class (Badger series)
  • Testing Method: Chronograph measurement, multiple charge weights, field observation

Published load data used for comparison typically reflects:

  • handgun platforms
  • 20″+ rifle barrels
  • shared COAL values between pistol and rifle data

No pressure instrumentation was used; all testing remained within published charge envelopes.

Observations

  1. Velocity Deficit
    • Recorded velocities were approximately 400–600 fps lower than commonly published data.
    • Velocity spreads were consistent across multiple charge weights.
  2. Incomplete Powder Burn
    • Visible unburned powder was present after firing.
    • Residue suggested insufficient dwell time for full combustion before bullet exit.
  3. Charge Weight Insensitivity
    • Increasing charge weight did not proportionally recover velocity.
    • Indicates a burn-rate mismatch rather than under-charging.
  4. Higher-Than-Expected Muzzle Pressure
    • Audible and tactile characteristics suggested combustion continuing near or beyond muzzle exit.
    • Consistent with powders optimized for longer barrels.

Interpretation

IMR 4227 is commonly used in magnum handgun applications and occasionally listed for rifle use. However, in a 16.1″ lever-gun barrel, the powder appears to retain a burn profile more appropriate for longer dwell times than the platform can provide.

This mismatch explains:

  • reduced velocity
  • incomplete combustion
  • diminished efficiency despite safe charge levels

The behavior aligns with known mechanical distinctions between revolver, carbine, and rifle platforms chambered for the same cartridge.

Broader Implication

Most published .44 Magnum load data does not meaningfully distinguish between:

  • handgun barrels
  • short lever-gun barrels
  • longer rifle barrels

As a result, shooters using compact lever guns may experience:

  • unexplained velocity loss
  • inconsistent expectations
  • difficulty reconciling real-world results with manuals

This gap is mechanical, not anecdotal.

What This Suggests (Without Making Prescriptions)

This report does not propose alternative powders or loads.
It establishes that:

  • Barrel length materially alters powder efficiency
  • Burn rate selection must match dwell time, not cartridge name
  • Shared handgun/rifle data obscures platform-specific behavior

Further optimization requires powder choices better aligned with short-barrel pressure curves.

Related Chapters & Technical Notes:

TN-17 — Rifle vs Revolver Loads: Mechanical Realities

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