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.
The H4350-class Enduron, and the one most people actually wanted: .30-06, .270 Winchester, .300 WSM and 6.5 Creedmoor all sit right in its window. The copper-fouling reducer and the temperature stability are the reasons to pick it over classic IMR 4350, and shooters who used it generally liked it. The catch is availability. This is a powder people now talk about in the past tense, and the Enduron line's supply is currently uncertain enough that you should not plan a season around it.
- .30-06 Springfield
- 6.5 Creedmoor
- .270 Winchester
- .300 WSM
Who has IMR Enduron 4451 today
Checked October 10Out of stock at every store we track
| Store | Size | Shelf | In hand /lb | Stock |
|---|---|---|---|---|
| Hodgdon (direct)Terms not published | 8 lb | $453.99 | $60.68 est. | Out |
| Hodgdon (direct)Terms not published | 1 lb | $66.99 | $98.43 est. | Out |
“In hand” is the shelf price plus that store’s hazmat fee and shipping, spread over one container. Stock is checked once a day — confirm on the store’s page before ordering. Compare all powders →
Specifications
| Manufacturer | IMR |
|---|---|
| Product family | IMR Enduron |
| Status | Currently produced |
| Application | rifle |
| Grain form | extruded |
| Lee VMD (bulk density) | 0.0713 cc per grain · 0.91 g/cc |
| 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 |
Grain shape
Neutral-burning extruded tube with a thicker web than IMR Enduron 4166; wall thickness is the burn-rate knob across the whole Enduron ladder. Full-length kernels, so weigh rather than throw if you care about your velocity spread.
Why geometry decides burn rate more than chemistry does: Shape Is the Product.
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
The specifications above come from IMR's own published documentation, linked below. The two “RCM's read” sections are ours, not theirs — our assessment of what this powder is like to load, drawn from its published characteristics and from what handloaders consistently report. No manufacturer endorses them and no source below backs them. If you think we have one wrong, tell us — we would rather fix it.