IMR Enduron
IMR Enduron 4451
A match-grade mid-burn-speed rifle powder for standard hunting cartridges and short magnums. Hodgdon states it performs comparably to Hodgdon H4350 but with materially different charge weights.
Specifications
| Manufacturer | IMR |
|---|---|
| Product family | IMR Enduron |
| Status | Currently produced |
| Application | rifle |
| Grain form | extruded |
| Composition | single-base |
| Temperature stable | Yes — claimed by the manufacturer |
| Burn-rate position | 149 of 198 (fastest = 1) — what this means |
| Typical cartridges | 270 Winchester, 30-06 Springfield, 300 Winchester Short Magnum, 6.5 Creedmoor |
Enduron powders are marketed on four shared claims: a copper fouling eliminator additive, reduced sensitivity to temperature change, loading density matched to the intended cartridge class, and a REACH-compliant formulation. Extruded single-base, made in Canada.
Burn rate
Mid-range of the Enduron line; just slower than IMR 4350 and close to Hodgdon H4350.
Chart agreement: consistent, but single-publisher - ranked only by Hodgdon (and echoed by the Wolfe/LoadData compilation). No second manufacturer's chart carries it, so the position is uncorroborated. Ranked by: Hodgdon, Wolfe/LoadData.
Powders charted near it — neighbours on the chart are not substitutes, and adjacency tells you nothing about what charge either one takes:
- Norma URP (position 146)
- Vihtavuori N550 (position 147)
- IMR 4350 (position 148)
- Alliant Reloder 16 (position 150)
- Hodgdon H4350 (position 151)
- Alliant Reloder 17 (position 152)
What reloaders say about it
Unverified community anecdote. The following is a summary of what handloaders report in public forums. It is not manufacturer information, it has not been tested, it may be wrong, and it contains no load data by design. Treat it as colour, not guidance.
Mentioned wistfully as a powder users liked and can no longer buy. Recorded here as part of the 2025-2026 discontinuation picture rather than for its handling characteristics.
- discontinued
- remembered fondly for .30-06-class loads
Availability: Reported discontinued; users describe it as a loss.
Consensus level: single report. Drawn from thread 1.
Sources
Other IMR powders
Verify the charge, not just the recipe
Good data gets you a safe starting point. It does not tell you what actually went into the case on stroke 340 — a bridged measure, a double charge, a squib. That is what an RCM Laser Powder Check is for.