IMR Enduron
IMR Enduron 8133
Intended for the largest overbore magnum cases, where a very slow powder is needed to fill the case and deliver uniform pressures. Hodgdon states it performs comparably to Hodgdon Retumbo 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 | 188 of 198 (fastest = 1) — what this means |
| Typical cartridges | 6.5-300 Weatherby Magnum, 264 Winchester Magnum, 28 Nosler, 300 Remington Ultra Magnum |
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
The slowest powder in the Enduron family; in the overrun-magnum range near Hodgdon Retumbo.
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 217 (position 185)
- Hodgdon Retumbo (position 186)
- Winchester StaBALL HD (position 187)
- Vihtavuori N568 (position 189)
- Ramshot LRT (position 190)
- Vihtavuori N570 (position 191)
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.