Summary

During structured load testing in a .44 Magnum lever-action rifle, accuracy degradation was observed at mid-range charge weights. Lighter and heavier charges produced comparatively tighter and more predictable groupings, while intermediate charges showed increased dispersion without corresponding velocity anomalies.

This report documents the observation and places it within the known interaction between barrel harmonics, dwell time, and pressure curve alignment.

Test Context

  • Platform: Marlin 1894 SBL
  • Barrel Length: 16.1″
  • Caliber: .44 Magnum
  • Bullet: 240-grain Badger
  • Powder: IMR 4227
  • Test Method:
    • Three charge weight bands
    • Six rounds per charge band
    • Chronograph measurement
    • Fixed rest shooting

All loads remained within published charge envelopes. No pressure instrumentation was used.

Observations

  1. Accuracy Degradation at Mid-Range Charges
    • The intermediate charge weight produced visibly wider group dispersion.
    • Vertical and horizontal spread increased without clear pattern.
  2. Stable Behavior at Charge Extremes
    • Both lighter and heavier charges showed more consistent grouping.
    • Impact points clustered more tightly despite differing velocities.
  3. Velocity Consistency Did Not Predict Accuracy
    • Chronograph data showed no extreme velocity spread at the mid-range charge.
    • Indicates accuracy loss was not driven by velocity variance alone.
  4. Repeatability Across Strings
    • The behavior was consistent across multiple firing strings.
    • Suggests a structural interaction rather than shooter inconsistency.

Interpretation

Barrel harmonics and bullet dwell time interact dynamically with the pressure curve produced by a given load. At certain charge weights, the timing of bullet exit can coincide with unfavorable barrel movement, producing accuracy instability even when velocity appears consistent.

In this case, the mid-range charge likely aligned bullet exit with a harmonic state that amplified dispersion, while the lighter and heavier charges exited at more stable points in the barrel’s oscillation cycle.

This behavior is consistent with known accuracy “nodes” observed in both rifle and pistol-caliber carbines.

Why This Matters

Many shooters assume accuracy improves monotonically with charge weight progression. This observation reinforces that:

  • Accuracy nodes are not linear
  • Mid-range loads are not inherently safer or more stable
  • Velocity consistency alone does not guarantee grouping consistency
  • Barrel length and pressure timing matter as much as charge weight

Understanding this prevents wasted range time and unnecessary component burn.

What This Report Does Not Claim

  • It does not identify a universal accuracy load
  • It does not generalize beyond the tested platform
  • It does not prescribe specific charge weights

It documents a repeatable mechanical behavior that shooters should expect and account for during load development.

Related Chapters & Technical Notes:

TN-17 — Rifle vs Revolver Loads: Mechanical Realities

Chapter 32 — Barrel Dynamics & Pressure Behavior in Pistol-Caliber Lever Rifles

TN-08 — Barrel Length, Velocity & Dwell Time

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