Published: 2026 | Last updated: April 2026
Hodgdon Retumbo is a single-base, ultra-slow-burning extruded rifle powder from the Hodgdon Extreme series, engineered specifically for the class of overbore cartridges where every other slow powder in the lineup reaches its limit. It was developed around cases like the 300 Remington Ultra Magnum, 30-378 Weatherby Magnum, and 338 Lapua Magnum – cartridges with so much case capacity relative to bore diameter that a powder in the Hodgdon H1000 burn rate range reaches maximum pressure too quickly and delivers peak energy before the bullet has cleared the barrel.
Two things define Retumbo’s position in the market. First, it belongs to the Hodgdon Extreme series – which means it carries the genuine, measured temperature stability that distinguishes Extreme series powders from conventional propellants. Field-verified velocity variation of 0.16-0.5 fps per degree Fahrenheit is among the most stable figures in the slow-magnum category. Second, it delivers 40-100 fps more velocity than H1000 in its primary overbore cartridge applications while maintaining that stability. For a reloader working with 300 RUM or 30-378 Weatherby, that combination of stability and velocity is not available from any other single powder.
Powder Description and Technical Profile
Hodgdon Retumbo is a single-base, extruded stick powder from the same Extreme series family as Hodgdon H1000, Hodgdon H4831, and Hodgdon Varget. The single-base formulation – nitrocellulose without nitroglycerin – is the foundation of the Extreme series’ temperature stability. Without nitroglycerin, the energy release mechanism is governed by a single chemical reaction rather than the interaction between nitrocellulose and nitroglycerin, which is inherently more predictable across temperature ranges.
The grain geometry is extruded stick format, cut to a specific length calibrated for the large case volumes where Retumbo operates. Longer sticks provide more control over surface-to-volume ratio and burn rate than shorter-cut grains. In large-capacity magnum cases, the larger sticks also settle more consistently – an air pocket-free powder column packed against the primer produces more consistent ignition start conditions than a loosely settled column.
Bulk density is 0.925 g/cc – higher than H1000’s 0.910 g/cc, which gives Retumbo slightly better mass per unit of case volume. In the 300 RUM and 30-378 Weatherby cases – which hold 110+ grains of water capacity – adequate powder density is a practical requirement for reaching maximum pressure at charge weights that fit the case without excessive compression.
The Extreme series chemistry that makes the temperature stability possible involves a specific deterrent and chemical stabilizer package applied to the grain surface during manufacturing. This package regulates burn rate as ambient temperature changes, producing the measurably flat velocity curve that Extreme series users depend on for year-round load consistency. The identical chemistry that makes Hodgdon Varget the benchmark for 308 Winchester precision loading makes Retumbo the benchmark for ultra-overbore precision loading.
Strengths:
- Extreme series temperature stability (0.16-0.5 fps per degree Fahrenheit) – the most stable figure in the slow-magnum burn rate range. Loads developed at summer range temperatures hold their point of impact in winter field conditions without recalculation
- 40-100 fps velocity advantage over H1000 in primary overbore applications – the slower burn rate is better matched to the largest case volumes, sustaining pressure through the bore more efficiently
- Single-base cleanliness – complete combustion at appropriate pressure levels with minimal carbon residue relative to double-base alternatives in the same burn rate position
- Part of the Hodgdon Extreme series – the deepest published data library and most widely documented slow-magnum powder in North American reloading manuals
- Does not require compressed loads in most primary overbore applications – the high density allows maximum charge weights to fit the case without compression at appropriate pressure levels
- Magnum primer compatibility is straightforward – the Extreme series chemistry is designed for use with magnum large rifle primers across all overbore applications
Limitations:
- Extruded stick geometry meters less consistently than ball powders – precision auto-dispensers or hand-weighing are recommended for charge weights where ±0.3 grains from a volumetric measure is unacceptable
- Too slow for standard-capacity cartridges – 308 Winchester, 270 Winchester, and similar produce incomplete combustion and elevated standard deviations with Retumbo at typical bullet weights
- Market availability can tighten during demand cycles – the concentrated user base of Ultra Magnum and overbore shooters creates periodic supply constraints
- Not the maximum-velocity option against double-base alternatives – Alliant Reloder 26 and Alliant Reloder 33 may produce more fps at comparable pressures in some applications. The stability trade-off is substantial
- Requires magnum primers in all primary overbore applications – standard large rifle primers produce inconsistent ignition in large-capacity cases with this slow-burning powder
Technical Characteristics
| Property | Specification |
|---|---|
| Manufacturer | Hodgdon Powder Company (USA) |
| Series | Hodgdon Extreme |
| Type | Single-Base Extruded (Stick) |
| Bulk Density (g/cc) | 0.925 |
| Burn Rate Category | Ultra-Slow Rifle |
| Temperature Stability | 0.16-0.5 fps / °F |
| Primer Requirement | Large Rifle Magnum |
The Extreme Series Advantage – What Temperature Stability Actually Means at Distance
The 0.16-0.5 fps per degree Fahrenheit stability figure from the Hodgdon Extreme series is the most commonly cited attribute of Retumbo, but it is worth translating to practical field terms to understand why it matters specifically at the distances where overbore cartridges are typically deployed.
A 300 RUM load with a 210-grain high-BC bullet at 3,050 fps is typically used at 800-1,500 yards – the range where the cartridge’s ballistic advantage over 300 Win Mag becomes meaningful. At those distances, small velocity variations at the muzzle produce large vertical dispersion at the target.
Consider the common scenario: load development in August at 85°F, hunting season in October at 45°F – a 40°F drop.
- With Hodgdon Retumbo at 0.35 fps/°F: 40°F x 0.35 = 14 fps velocity reduction. At 1,200 yards with a 210-grain projectile, that 14 fps produces approximately 1 inch of additional drop – negligible for practical field use.
- With Alliant Reloder 26 at 0.5 fps/°F: 40°F x 0.5 = 20 fps velocity reduction – still manageable.
- With Alliant Reloder 25 at 1.75 fps/°F: 40°F x 1.75 = 70 fps velocity reduction – approximately 4-5 additional inches of drop at 1,200 yards.
At 800 yards, these differences are all manageable. At 1,200-1,500 yards where the overbore cartridges are specifically deployed, the Extreme series stability becomes the property that keeps the load consistent without recalculation.
| Powder | Stability | 40°F Swing | 80°F Swing |
|---|---|---|---|
| Hodgdon Retumbo | 0.16-0.5 fps/°F | 7-20 fps | 13-40 fps |
| Hodgdon H1000 | ~0.21 fps/°F | ~8 fps | ~17 fps |
| Alliant Reloder 26 | ~0.5 fps/°F | ~20 fps | ~40 fps |
| Alliant Reloder 25 | ~1.75 fps/°F | ~70 fps | ~140 fps |
| Alliant Reloder 33 | ~1.1-1.4 fps/°F | ~44-56 fps | ~88-112 fps |
Burn Rate Comparison and Competing Powders
| Powder | Type | Density (g/cc) | Stability | Key Character |
|---|---|---|---|---|
| Hodgdon H1000 | Single-Base Extruded | 0.910 | Extreme | Faster – 300 Win Mag, 7mm Rem Mag focus |
| Alliant Reloder 26 | Double-Base Extruded | 0.989 | Good | Faster – 300 Win Mag, EI impregnation |
| Vihtavuori N570 | Double-Base Extruded | 0.960 | Good | Similar – European, large-kernel |
| Hodgdon Retumbo | Single-Base Extruded | 0.925 | Elite | Reference – ultra-overbore specialist |
| Norma MRP | Single-Base Extruded | 0.910 | Moderate | Similar-Slower – European single-base |
| Hodgdon US 869 | Double-Base Spherical | 1.050 | Moderate | Slower – 30-378 Weatherby, 50 BMG range |
| Alliant Reloder 33 | Double-Base Extruded | 0.985 | Moderate | Slower – 338 Lapua, 300 RUM heavy |
| Accurate MagPro | Double-Base Spherical | 0.950 | Moderate | Similar – ball metering, less stable |
vs. Hodgdon H1000: The primary Extreme series comparison within the same product family. H1000 burns slightly faster than Retumbo and is the standard Extreme series choice for 300 Winchester Magnum and 7mm Remington Magnum applications. In those cartridges, Retumbo is typically too slow for efficient combustion – pressure peaks too late and velocity is often no better or worse than H1000 in the correctly matched case. Retumbo earns its velocity advantage specifically in cases larger than 300 Win Mag and 7mm Rem Mag where H1000’s burn rate peaks too early in the larger powder column. The demarcation is approximately: H1000 for standard belted magnums, Retumbo for Ultra Magnums and 378-based cases.
vs. Alliant Reloder 26: Reloder 26 carries Nitrochemie’s EI impregnation technology producing approximately 0.5 fps/°F stability – better than most double-base powders but not matching Retumbo’s Extreme series 0.16-0.5 fps/°F. It also provides higher energy density from double-base chemistry, which can produce 30-60 fps more velocity in some overbore applications. The trade-off is clear: Retumbo for maximum seasonal consistency year-round; Reloder 26 for maximum velocity with acceptable seasonal variation. For 300 RUM hunters who shoot from August through January across significant temperature ranges, Retumbo’s stability advantage is worth the velocity trade.
vs. Vihtavuori N570: N570 is a double-base European powder at a comparable burn rate with a strong reputation in 338 Lapua Magnum precision competition. Its very large kernel size produces more metering variance than Retumbo in standard volumetric measures. North American availability is more limited. Retumbo has the advantage of the Hodgdon Extreme series stability designation and deeper North American data library. N570 is a legitimate alternative for reloaders who access it through European competition shooting circles.
vs. Alliant Reloder 33: Reloder 33 burns slightly slower than Retumbo and is specifically designed for the heaviest-bullet 338 Lapua Magnum applications where Retumbo may burn slightly too fast for maximum efficiency. It carries double-base chemistry with notably more temperature sensitivity (1.1-1.4 fps/°F). For 338 Lapua with 250-285 grain bullets in a 27-30 inch barrel where maximum velocity is the goal and temperature can be managed, Reloder 33 may produce more fps. For hunters or competitors who need year-round seasonal consistency, Retumbo’s Extreme series stability is the more practical choice.
vs. Hodgdon US 869: Hodgdon US 869 is a double-base spherical powder at a slower burn rate than Retumbo, intended for the 30-378 Weatherby class and the largest practical sporting cases. Its ball geometry meters with good consistency but its double-base chemistry and slower burn rate place it in a different application niche. For most of Retumbo’s primary cartridges, US 869 is too slow; it belongs in the largest overbore cases that even Retumbo cannot serve efficiently.
Recommended Cartridges and Applications
Hodgdon Retumbo is specifically designed for high-capacity, overbore rifle cases where the powder-to-bore-diameter ratio requires an ultra-slow burn to sustain pressure through the bore without early pressure decay. It is not suited to standard or medium-capacity cartridges.
| Cartridge | Bullet Weight Range | Notes |
|---|---|---|
| 300 RUM | 180-230 gr | Flagship application |
| 30-378 Weatherby Magnum | 180-220 gr | Classic overbore application |
| 338 Lapua Magnum | 250-300 gr | Primary ELR match application |
| 300 PRC | 200-230 gr | Purpose-built ELR cartridge |
| 7mm PRC | 160-195 gr | Modern ELR 7mm |
| 338 RUM | 250-300 gr | Ultra-mag large caliber |
| 28 Nosler | 160-195 gr | High-BC 7mm overbore |
| 300 Norma Magnum | 200-230 gr | ELR precision and military |
| 7mm Remington Magnum | 175-195 gr | Heavy-bullet specific only |
The 300 RUM is the cartridge most historically associated with Retumbo. When Remington introduced the 300 Ultra Magnum, the powder industry had no ready answer for its enormous case capacity – standard slow magnum powders like H1000 did not produce adequate pressure from the large case. Retumbo was developed to address that gap specifically. The 300 RUM with 210-220 grain high-BC bullets and Retumbo at 3,000-3,100 fps from a 26-inch barrel represents the combination the powder was built for.
The 338 Lapua Magnum application covers the 250-285 grain bullet weight range effectively. For the heaviest 285-300 grain projectiles at maximum velocity in barrels of 27-30 inches, Alliant Reloder 33 or Vihtavuori N570 may produce better efficiency – Retumbo is slightly fast for those combinations. For standard 250-285 grain ELR competition loads in 338 Lapua, Retumbo with its Extreme stability is a strong choice for year-round competition use.
The 7mm Remington Magnum application is specifically limited to heavy-bullet loads in the 175-195 grain range where the additional bullet bearing surface reduces effective case volume enough to shift the optimal burn rate toward Retumbo’s position. Standard 7mm Rem Mag loads with 160-175 grain bullets are better served by H1000 or Alliant Reloder 26. Using Retumbo with 160-grain bullets in 7mm Rem Mag produces incomplete combustion and elevated standard deviations.
Seating Depth and Load Density – The Accuracy Connection
The Expert Pro Tip in the original article – that many reloaders find Retumbo produces tightest groups with bullets seated close to the rifling – reflects a real phenomenon worth understanding mechanically.
With a very slow-burning powder in a large case, the initial moments after primer ignition are critical. The powder column begins burning from the primer end, and the bullet needs to be held in place long enough for initial pressure to build before it releases. If the bullet releases too easily (shallow seating, loose neck tension), the case has too little back-pressure in the first milliseconds and the slow powder ignites inconsistently across the grain surfaces.
Seating bullets 0.010-0.020 inches from the rifling lands – when the rifle’s magazine and chamber geometry permits – creates a situation where the bullet’s initial resistance to movement is partly provided by its contact with the lands rather than solely by neck tension. This slightly elevated initial resistance allows the primer flash to more consistently initiate the slow powder column before the bullet begins moving.
This principle is not unique to Retumbo but is more pronounced with very slow powders in large cases because the timing of the pressure build-up relative to bullet release is more critical. Apply it within safe overall length limits for your specific rifle’s chamber and magazine – never exceed a COAL that prevents safe magazine function or produces stuck cases.
Bullets
Hodgdon Retumbo produces best results with heavy, high-BC projectiles that generate adequate start pressure in large overbore cases and have sufficient bearing surface to benefit from the sustained pressure profile of an ultra-slow powder.
| Brand | Model | Weight | Cartridge | Application |
|---|---|---|---|---|
| Berger | Hybrid Target | 195-230 gr | 300 RUM / 300 PRC / 300 Norma | ELR Competition |
| Berger | LRHT | 195-230 gr | 300 RUM / 300 Norma | Long-Range Hunting |
| Berger | OTM Tactical | 285-300 gr | 338 Lapua Magnum | Military/ELR Match |
| Hornady | ELD-M | 195-230 gr | 300 RUM / 300 PRC | Long-Range Match |
| Hornady | ELD-X | 195-212 gr | 300 RUM / 7mm PRC | Long-Range Hunting |
| Sierra | MatchKing | 200-250 gr | 300 RUM / 338 Lapua | Competition |
| Sierra | Tipped MatchKing | 195-230 gr | 300 RUM / 300 PRC | Match Accuracy |
| Lapua | Scenar-L | 250-300 gr | 338 Lapua Magnum | ELR Competition |
| Nosler | AccuBond | 200-225 gr | 300 RUM / 300 PRC | Bonded Hunting |
| Nosler | Partition | 200-225 gr | 300 RUM | Classic Big Game |
| Barnes | LRX | 180-220 gr | 300 RUM / 338 Lapua | Lead-Free Long Range |
| Barnes | TTSX | 180-220 gr | 300 RUM | Lead-Free Hunting |
The Berger Hybrid Target in 215-230 grain with Retumbo in 300 RUM or 300 Norma Magnum is the defining ELR competition combination for these cartridges – high BC, high velocity from the large case, and Extreme series stability that keeps the load consistent from summer qualification shoots to winter competition. This combination has appeared at the top of ELR competition results consistently.
Primers
Magnum large rifle primers are mandatory for Hodgdon Retumbo in all overbore applications. The combination of a slow burn rate, large powder column, and the high-density Extreme series grain chemistry requires the brisance of a magnum primer to initiate consistent ignition throughout the powder column. Standard large rifle primers produce hangfires, incomplete burns, and elevated extreme spread in large overbore cases with this slow powder.
| Primer | Type | Application |
|---|---|---|
| Federal GM215M | Large Rifle Magnum Match | Competition precision – gold standard |
| CCI 250 | Large Rifle Magnum | Reliable all-weather hunting and competition |
| Winchester WLRM | Large Rifle Magnum | Consistent hunting and match loads |
| Remington 9-1/2M | Large Rifle Magnum | Standard magnum choice |
| Federal 215 | Large Rifle Magnum | Maximum ignition for largest cases |
| CCI BR-2 | Large Rifle Benchrest | Competition where magnum brisance is sufficient |
| RWS 5337 | Large Rifle Magnum | Premium European precision option |
| Fiocchi Large Rifle Magnum | Large Rifle Magnum | Consistent alternative |
For 338 Lapua Magnum and 300 RUM precision competition, the Federal GM215M is the standard competition primer pairing – its match-grade brisance tolerances complement Retumbo’s Extreme series consistency to produce the lowest extreme spreads achievable in these large overbore cases.
Primer seating depth consistency is critical with large slow-burning powder columns. Use a quality bench priming tool like the Forster Co-Ax Bench Priming Tool or K-M Primer Deluxe Hand Priming Tool to seat primers to a consistent, verifiable depth. A primer seated 0.003 inches shallow compared to another delivers measurably less ignition energy – a variable that shows up in velocity standard deviation even when everything else is consistent.
Metering and Equipment Compatibility
Hodgdon Retumbo is an extruded stick powder with larger kernels than short-cut alternatives. In standard drum-style volumetric measures, charge-to-charge variance of 0.2-0.4 grains is typical – acceptable for hunting ammunition, not for precision match-grade loading.
For precision competition loading in 338 Lapua and 300 RUM where single-digit standard deviations are the goal, a precision digital auto-dispenser that weighs each charge rather than measuring volumetrically is the appropriate tool. The RCBS ChargeMaster Supreme, RCBS MatchMaster, Hornady Auto-Charge Pro, and Frankford Arsenal Intellidropper 2.0 all handle large-charge extruded powders reliably.
For hunting ammunition production where 0.2-0.3 grain charge variance is acceptable, the Redding Match Grade 3BR Powder Measure with a consistent cycling speed delivers adequate consistency. Using a long drop tube to settle the large kernels in the case before seating bullets reduces the risk of inconsistent compression from uneven powder column packing.
The 90%+ case fill target applies here: at the large charge weights typical of Retumbo applications (80-100+ grains), position sensitivity of the powder column matters less in percentage terms than in smaller cases, but ensuring the powder column is consistently settled against the primer is still good practice. Cases should be loaded upright from charging through seating wherever possible.
Reloading Safety Notes
All charge weights must come from current published Hodgdon load data for Retumbo specifically. Hodgdon publishes free load data online with regular updates. Do not substitute H1000, Alliant Reloder 26, or Alliant Reloder 33 charge weights for Retumbo without independent verification. The density and burn rate differences between these powders are large enough that charge weights are not interchangeable.
Start 10% below the listed maximum and work up in 0.3-grain increments. In large overbore cases at slow burn rates, the pressure curve can remain relatively flat through most of the charge range before rising steeply near maximum. Do not skip increments near maximum. Watch for pressure signs: flattened or cratered primers, stiff bolt lift, ejector marks on case heads.
Case fill approaching 100% requires specific care. Near compressed loads, the force applied to the bullet during seating must be consistent between rounds. Inconsistent bullet seating force on compressed powder charges introduces charge density variation that affects ignition start pressure. A quality bullet seating die with a micrometer adjustment verified to the same position every session is appropriate for near-maximum loads.
See the overpressure in reloading guide for systematic pressure sign identification.
FAQ
When should I choose Retumbo over H1000?
The general demarcation: H1000 for standard belted magnums (300 Win Mag, 7mm Rem Mag with standard-weight bullets), Retumbo for Ultra Magnums and large overbore cases (300 RUM, 30-378 Weatherby, 338 Lapua). In 300 Win Mag with 180-200 grain bullets, H1000 is typically the better Extreme series choice. The crossover point is cartridges with case capacities significantly larger than 300 Win Mag.
Can Retumbo be used in 300 PRC?
Yes – 300 PRC is specifically listed in Hodgdon’s published data for Retumbo with appropriate bullet weights. The 300 PRC was purpose-designed for high-BC heavy bullets at extreme long range, and Retumbo’s burn rate is well-matched to the case capacity with 200-225 grain projectiles.
How does Retumbo’s stability compare to Reloder 26?
Retumbo (Extreme series, 0.16-0.5 fps/°F) is substantially more stable than Alliant Reloder 26 (EI impregnation, ~0.5 fps/°F). The Extreme series single-base chemistry with its specific stabilizer package produces stability that EI-impregnated double-base powders approach but do not quite match. For year-round hunting from summer through winter, Retumbo’s stability is the more conservative and reliable choice.
Is Retumbo appropriate for 338 Lapua with 300-grain bullets at ELR velocities?
Retumbo is the appropriate choice for 338 Lapua with 250-285 grain bullets where Extreme series stability is the priority. For maximum velocity in 338 Lapua with the heaviest 285-300 grain bullets at ELR velocities in 28-30 inch barrels, Alliant Reloder 33 or Vihtavuori N570 may produce better efficiency from their slightly slower burn rate and higher energy density. The stability trade-off is significant: Retumbo provides year-round consistent performance; Reloder 33 requires seasonal load adjustment.
Conclusion
Hodgdon Retumbo occupies a specific and defensible position in the slow-magnum powder market that it has held since its introduction. The combination of Extreme series temperature stability and the 40-100 fps velocity advantage over H1000 in ultra-overbore cases is genuinely unique. No other powder provides that specific combination from a North American manufacturer with equivalent published data support.
The cases where it is genuinely the best choice are clear: 300 RUM with 200-220 grain bullets, 338 Lapua with 250-285 grain standard competition weights, 300 PRC at ELR velocities, and any of the large 30-caliber overbore cases where H1000 reaches its limit. Outside those applications, other powders serve better.
Choose Hodgdon Retumbo if you load 300 RUM, 338 Lapua, 300 PRC, or similar high-capacity overbore cartridges and want Extreme series year-round stability with maximum velocity in that case class. Choose Hodgdon H1000 if your primary cartridges are 300 Winchester Magnum or 7mm Remington Magnum at standard-to-heavy bullet weights where Retumbo is slightly too slow. Choose Alliant Reloder 26 if maximum velocity with acceptable seasonal variation is the priority over the ultimate Extreme series stability. Choose Alliant Reloder 33 if maximum velocity in 338 Lapua with 285-300 grain bullets is the specific objective and you can manage the greater temperature sensitivity.
Editorial note: Originally published 2026, revised April 2026. The revision added the practical temperature stability comparison with specific fps numbers across 40°F and 80°F swings at ELR distances, corrected the 7mm Remington Magnum application to specify heavy bullets only, corrected the Reloder 33 description (it is an extruded double-base powder, not spherical as the original stated), added the seating depth section with the mechanical explanation for why COAL near lands benefits slow-powder consistency, extended the bullet and primer tables with full internal links, added a case fill and compression note for near-maximum charges, and added a reloading safety section with compressed-load specific guidance.
