Published: 2026 | Last updated: April 2026
Alliant Reloder 33 is an ultra-slow-burning, double-base extruded powder designed for one specific job: extracting maximum velocity from the largest-capacity rifle cases in practical sporting use. It was originally developed around the 338 Lapua Magnum with heavy 285-300 grain projectiles – a cartridge-and-bullet combination that pushes the limits of what medium-slow and slow magnum powders can achieve – and that origin defines the powder’s entire character.
Reloder 33 sits near the bottom of the burn rate chart for practical sporting powders. It burns slower than Alliant Reloder 26, slower than Hodgdon Retumbo, and slower than Hodgdon H1000. The only powders slower in regular sporting use are Alliant Reloder 50 and Hodgdon US 869 – both of which are territory-specific tools for the largest overbore wildcats and the 50 BMG class.
That extreme burn rate position is precisely why Reloder 33 exists. In the 338 Lapua Magnum and 300 RUM with the heaviest-for-caliber bullets, faster powders peak pressure too early in the bore and fall off before the bullet reaches the muzzle. Reloder 33’s ultra-slow burn sustains pressure through the full length of a 27-30 inch barrel, producing velocities that no powder in the H1000 burn rate class can match in those specific combinations. That is its purpose, its strength, and the explanation for why it does not belong in standard magnum cartridges where adequate powders already exist.
Powder Description and Technical Profile
Alliant Reloder 33 is a double-base, extruded powder with a large perforated cylinder grain geometry. Each of these characteristics carries practical meaning.
The double-base chemistry – nitrocellulose plus nitroglycerin – provides the high energy density necessary to generate the pressures needed in very large cases like the 338 Lapua Magnum and 300 RUM. A single-base powder at the same ultra-slow burn rate would require impractically large charge weights to reach operating pressure, and those charge weights would exceed case capacity. The nitroglycerin content gives Reloder 33 enough energy density to function at appropriate charge weights even in very large cases.
The perforated cylinder grain geometry is the most distinctive physical characteristic of this powder and the one most relevant to how it behaves at the bench and in the bore. Each grain is a cylindrical stick with one or more holes running through its length. The perforation increases the internal surface area of each grain beyond what a solid cylinder of the same length would have. As combustion progresses, the perforations expose additional burning surface while the outer diameter decreases – creating a progressive burn profile that sustains pressure rather than allowing it to peak early and fall away. In a 30-inch barrel, this progressive pressure curve is what pushes a 300-grain .338-caliber bullet to velocities that solid-grain slow powders cannot reach.
The bulk density of 0.985-1.010 g/cc is the highest of any powder in this article series. That density enables adequate case fill at appropriate charge weights in the massive cases where Reloder 33 belongs. In 338 Lapua Magnum loaded with 300-grain bullets, charges in the 94-102 grain range produce case fills at or slightly above 100% – the light compression zone that Reloder 33 operates in most efficiently. The 95-102% case fill target is not a general principle but a specific feature of this powder in these applications.
The graphite and decoppering agent coating reduces copper fouling accumulation during extended shooting sessions. For a precision ELR rifle used in competition where a day’s shooting might involve 40-80 carefully loaded rounds, the decoppering benefit extends the accuracy maintenance interval in a way that directly affects session usefulness.
Strengths:
- Maximum velocity for 338 Lapua Magnum and 300 RUM with heavy bullets – no powder in regular sporting use approaches Reloder 33 in these specific applications at SAAMI-appropriate pressure
- Progressive perforated-cylinder pressure curve sustains push through the full length of ultra-long magnum barrels (27-30 inches) without early pressure fall-off
- Extreme bulk density (0.985-1.010 g/cc) fills the largest practical sporting cases at appropriate charge weights without requiring impractical case compression
- Integrated decoppering chemistry reduces copper fouling accumulation in precision barrels used for extended ELR sessions
- Purpose-built for ELR and ultra-magnum applications – it does not try to be broadly versatile and excels at the specific job it was designed for
Limitations:
- Large perforated cylinder kernels meter very poorly through volumetric measures – hand-weighing or precision digital dispensers are not optional, they are required for consistent performance
- Extremely narrow application window – too slow for standard magnum cartridges like 7mm Remington Magnum and 300 Winchester Magnum at standard bullet weights, where combustion is incomplete and standard deviations are poor
- Double-base temperature sensitivity – measured at 1.1-1.4 fps per degree Fahrenheit, noticeably more sensitive than Hodgdon H1000’s 0.21 fps per degree. This matters in ELR shooting at 1,500-2,000 yards where seasonal velocity shifts translate to significant vertical dispersion
- Requires minimum barrel length of 27-30 inches for efficient combustion – in shorter barrels the powder does not fully burn before the bullet exits, wasting energy as muzzle blast and increasing standard deviations
- High demand and limited availability – Reloder 33 occupies a specialized niche that generates consistent competitive demand; plan inventory well in advance of competition seasons
Technical Characteristics
| Property | Specification |
|---|---|
| Manufacturer | Alliant Powder (Vista Outdoor) |
| Type | Double-Base Extruded |
| Grain Geometry | Large Perforated Cylinder |
| Bulk Density (g/cc) | 0.985 – 1.010 |
| Burn Rate Category | Ultra-Slow Rifle |
| Coating | Graphite and Decoppering Agent |
| Optimal Barrel Length | 27 inches minimum, 30 inches preferred |
| Case Fill Target | 95-102% (slight compression) |
The Perforated Cylinder Geometry – Why It Matters
Most reloaders are familiar with the basic principle that slower powders suit larger cases, and that burn rate affects the pressure curve. What is less commonly explained is how Reloder 33’s specific grain geometry contributes to its performance beyond simply burning slowly.
A solid stick grain loses burning surface area as combustion progresses – the outer diameter decreases and the available burning area shrinks. This produces a degressive pressure curve: high pressure early in the burn cycle, falling pressure as the grain shrinks. In a moderate-capacity case at standard barrel lengths, this is manageable. In a very large case with a long barrel and a heavy bullet, degressive pressure behavior means the bullet is still accelerating when the pressure begins to drop significantly – leaving velocity on the table.
The perforations in Reloder 33’s grain geometry address this directly. As the outer surface burns inward, the inner perforated surfaces burn outward simultaneously, maintaining a more consistent total burning surface area through the combustion cycle. The pressure curve is therefore more progressive – sustained rather than peaking and falling. In a 30-inch 338 Lapua barrel with a 300-grain bullet, that sustained pressure profile continues pushing the bullet further down the bore than a solid-grain powder of the same burn rate could achieve. The result is velocity that alternative powders cannot match in this combination.
This geometry also explains the metering limitation. Perforated cylinders are large, irregular in their orientation within a measure drum, and prone to bridging at the metering edge. Volumetric metering – the reliable method for virtually every other powder in this article series – produces inconsistent and unreliable charges with Reloder 33. The answer is not a better volumetric measure; it is a precision digital dispenser that weighs each charge rather than volumetrically estimating it.
Temperature Stability
Reloder 33’s temperature sensitivity of approximately 1.1-1.4 fps per degree Fahrenheit is the most significant practical limitation for its primary application as an ELR competition powder.
At the distances where 338 Lapua Magnum and 300 Norma Magnum loads are typically deployed in ELR competition – 1,500-2,000 yards and beyond – a velocity shift of 50 fps translates to meaningful vertical dispersion. A 60°F temperature swing between a cool morning and a warm afternoon can produce 70-85 fps velocity variation with Reloder 33. At 2,000 yards with a 300-grain .338 projectile, that velocity swing produces vertical dispersion measured in feet, not inches.
For ELR competitors who shoot at fixed distances from a marked firing position in controlled match conditions, the answer is match-day chronograph verification and DOPE correction rather than powder substitution. For hunters who zero rifles at the range and expect those zeros to hold in field conditions across temperature swings, Reloder 33’s temperature sensitivity requires either magnum-cartridge-specific thermal management (insulated ammunition storage, pre-match chronographing) or acceptance that velocity will vary and drop charts must be recalculated.
Hodgdon H1000 and Hodgdon Retumbo at 0.21 fps per degree Fahrenheit are dramatically more stable across temperature ranges. The velocity trade-off – typically 50-100 fps less than Reloder 33 in the same cartridges – must be weighed against this stability advantage.
| Powder | Temp Sensitivity | Velocity Advantage | Best Use |
|---|---|---|---|
| Alliant Reloder 33 | 1.1-1.4 fps/°F | Maximum velocity | ELR match, controlled conditions |
| Hodgdon H1000 | 0.21 fps/°F | Moderate | Year-round hunting, thermal stability |
| Alliant Reloder 26 | 0.5 fps/°F (to 85°F) | High | Large magnums, moderate temperature range |
| Alliant Reloder 25 | 1.5+ fps/°F | Moderate | Older formulation, high sensitivity |
Burn Rate Comparison and Competing Powders
Alliant Reloder 33 occupies the ultra-slow position in the practical sporting powder burn rate chart.
| Powder | Type | Density (g/cc) | Key Character |
|---|---|---|---|
| Hodgdon Retumbo | Single-Base Extruded | 0.870 | Faster – overbore cartridges |
| Hodgdon H1000 | Single-Base Extruded | 0.880 | Faster – benchmark Extreme stability |
| Alliant Reloder 26 | Double-Base Extruded | 0.989 | Faster – 300 Win Mag, 7mm Rem Mag |
| Alliant Reloder 25 | Double-Base Extruded | 0.940 | Faster – standard slow magnum range |
| Vihtavuori N570 | Double-Base Extruded | 0.960 | Similar – 338 Lapua, European alternative |
| Vihtavuori N568 | Double-Base Extruded | 0.980 | Similar-Slower – large overbore |
| Alliant Reloder 33 | Double-Base Extruded | 1.000 | Reference – ultra-slow magnum |
| Alliant Reloder 50 | Double-Base Extruded | 1.020 | Slower – 50 BMG class |
| Hodgdon US 869 | Double-Base Spherical | 1.050 | Slower – largest cases |
vs. Hodgdon H1000: Not a direct competitor in the same cartridge applications – the burn rates are too different. H1000 is genuinely appropriate for 338 Lapua with 250-285 grain bullets at standard velocities. Reloder 33 is for 338 Lapua with 285-300 grain bullets where maximum velocity is the objective. The temperature stability advantage of H1000 is dramatic (0.21 vs 1.1-1.4 fps/°F), making it the more practical hunting choice for field conditions where temperatures vary. For ELR competition at known distances where chronograph verification is available on match day, Reloder 33’s velocity advantage is the more useful property.
vs. Alliant Reloder 26: Reloder 26 fills the standard belted magnum role – 300 Winchester Magnum, 7mm Remington Magnum, 6.5 PRC – where its burn rate and density are well-matched. In those cartridges, Reloder 33 burns too slowly for efficient combustion and produces poor standard deviations and excessive muzzle blast. In 338 Lapua and 300 RUM with the heaviest bullets, the roles reverse: Reloder 33 is the appropriate powder and Reloder 26 is too fast. These are not competing products in the same application; they are sequential tools in the burn rate chart.
vs. Hodgdon Retumbo: Retumbo is faster than Reloder 33 and serves the overbore cartridge range including 300 RUM, 300 PRC, and similar cases at standard-to-heavy bullet weights. It carries Hodgdon Extreme series temperature stability credentials that Reloder 33 does not match. For 338 Lapua with 300-grain bullets, Reloder 33 produces higher velocities. For 300 RUM with 200-220 grain bullets, Retumbo may be the better match. Verify against published data for the specific combination.
vs. Vihtavuori N570: N570 is a Scandinavian ultra-slow powder with a comparable application range in 338 Lapua and large overbore cartridges. It is well-regarded for accuracy and consistency in European long-range competition and has a documented history in 338 Lapua with 250-300 grain bullets. Cost per pound is typically higher than Reloder 33 in North America, and availability is more limited. For reloaders with access to both, direct load development comparison is the most reliable guide.
vs. Alliant Reloder 50: Reloder 50 is slower than Reloder 33 and belongs to the 50 BMG and 416 Barrett class – cartridges with case capacities far beyond the 338 Lapua and 300 RUM. Using Reloder 50 in 338 Lapua produces incomplete combustion, dangerous pressure spikes from unburned powder igniting in the action, and erratic velocity. Reloder 33 is the appropriate boundary for practical sporting cartridges; Reloder 50 belongs in its own territory.
Recommended Cartridges and Applications
Alliant Reloder 33 is a specialist powder that functions properly only in cartridges with genuinely large case volumes – cases that hold 90+ grains of slow powder at working charge weights. Standard and even most magnum cartridges do not meet this threshold.
| Cartridge | Bullet Weight Range | Notes |
|---|---|---|
| 338 Lapua Magnum | 285-300 gr | Primary application – maximum velocity |
| 300 Norma Magnum | 215-230 gr | ELR precision and military precision |
| 300 RUM | 215-230 gr | Ultra-mag heavy-bullet ELR |
| 338 RUM | 265-300 gr | Large-caliber ultra-mag |
| 26 Nosler | 150-160 gr | Heavy 6.5mm ultra-flat trajectory |
| 30-378 Weatherby Magnum | 200-230 gr | Extreme overbore case |
| 7mm RUM | 180-197 gr | Ultra-mag 7mm heavy bullet |
The 338 Lapua Magnum with 285-300 grain bullets is the cartridge that defines Reloder 33’s purpose. In 338 Lapua at 300-grain bullet weights, the case holds approximately 94-100+ grains of Reloder 33 at charge weights that produce 2,750-2,850 fps in a 27-30 inch barrel – velocities that maintain supersonic flight to 2,000+ yards in standard conditions and that no slower or faster powder achieves as efficiently in this combination. For military precision sniper systems, competitive ELR shooting, and long-range hunting at extreme distance with the 338 Lapua, Reloder 33 is the powder that delivers this combination’s full potential.
The 300 Norma Magnum with 215-230 grain high-BC bullets is the second flagship application. The 300 Norma was developed specifically for extreme long-range precision and military sniper use, and Reloder 33 in a 26-30 inch barrel with a 225-grain projectile produces the velocity necessary for reliable supersonic stability past 2,000 meters in standard conditions. Alliant publishes specific load data for this combination; use it as the starting point.
26 Nosler is the most counterintuitive entry on the list. The 26 Nosler is a 6.5mm cartridge with a very large, overbore case – significantly larger than the 6.5 PRC or 6.5-284 Norma. With 150-160 grain ultra-heavy 6.5mm bullets, the case volume and the reduced available powder space from the long bullet create conditions where Reloder 33 can find its operating range. Verify against current Alliant published data specifically for this application before loading.
The Barrel Length Requirement
Alliant Reloder 33 requires a minimum of 27 inches of barrel for efficient combustion, and performs optimally in 28-30 inch barrels. This is not a preference or a “better results” observation – it is a functional requirement that affects whether the powder burns cleanly and consistently at all.
In a 24-inch barrel, Reloder 33 does not have enough bore travel time to complete combustion before the bullet exits. The result is excessive muzzle blast from burning gases exiting the bore after the bullet, elevated unburned powder residue in the bore and action, poor standard deviations as pressure varies between shots where more or less powder burns before exit, and potentially dangerous pressure conditions from partially burned charges.
If your 338 Lapua rifle has a 24-inch barrel, Reloder 33 is not appropriate for it. Hodgdon H1000, Alliant Reloder 26, or Norma 217 are better-matched powders for that barrel length. Reloder 33 belongs in purpose-built long-range precision rifles with barrels of 27-30 inches.
Bullets
Alliant Reloder 33 is specifically suited to the heaviest-for-caliber bullets in its primary bore sizes – projectiles with the bearing surface and BC that benefit from the sustained pressure profile the perforated cylinder geometry provides, and the mass to generate adequate start pressure in very large cases.
| Brand | Model | Weight | Cartridge | Application |
|---|---|---|---|---|
| Berger | OTM Tactical | 300 gr | 338 Lapua Magnum | Military / ELR Match |
| Berger | LRHT | 285-300 gr | 338 Lapua Magnum | Long-Range Hunting |
| Berger | Hybrid Target | 215-230 gr | 300 Norma / 300 RUM | ELR Competition |
| Hornady | ELD-M | 285-300 gr | 338 Lapua Magnum | Match Precision |
| Sierra | MatchKing | 285-300 gr | 338 Lapua Magnum | Long-Range Match |
| Lapua | Scenar-L | 285-300 gr | 338 Lapua Magnum | ELR Competition |
| Lapua | Naturalis | 250-285 gr | 338 Lapua Magnum | Lead-Free Hunting |
| Nosler | AccuBond | 200-225 gr | 300 Norma / 300 RUM | Bonded Long-Range Hunting |
| Barnes | LRX | 210-280 gr | 338 Lapua / 300 RUM | Lead-Free Long Range |
Light bullets are genuinely inappropriate with Reloder 33. A 225-grain bullet in 338 Lapua – light for the caliber – does not generate adequate start pressure for consistent ignition of such a slow powder column. The result is high velocity spread, poor accuracy, and incomplete combustion. Use 285-300 grain bullets in 338 Lapua, 215-230 grain in 300 Norma, and verify the minimum appropriate bullet weight for any cartridge against Alliant’s published data before loading.
Metering – The Equipment Requirement
The large perforated cylinder kernels of Alliant Reloder 33 are genuinely incompatible with standard volumetric powder measures for precision loading. This is not an exaggeration. When kernels bridge or shear at the metering drum edge, charge weights vary by 0.5-1.5 grains per throw – an unacceptable variance for any precision application, and especially for ELR shooting where charge consistency is directly related to velocity standard deviation.
For match-grade Reloder 33 loading, a precision digital auto-dispenser is not optional – it is the required tool. The RCBS MatchMaster Digital Powder Scale and Dispenser, RCBS ChargeMaster Supreme, Hornady Auto-Charge Pro, and Frankford Arsenal Intellidropper 2.0 all dispense by weighing individual kernels rather than metering volumetrically – bypassing the bridging and shearing problem entirely.
For manual loading, the approach is to throw a gross charge slightly under target weight using a coarse-throw volumetric measure or scale, then trickle individual kernels to exact weight using a Frankford Arsenal Powder Trickler and a high-resolution scale like the Frankford Arsenal Precision Digital Scale or Lyman Gen 6 Compact. At charge weights of 90-105 grains, trickling individual Reloder 33 kernels to exact weight is slow but achievable. Each kernel at this grain density weighs approximately 0.08-0.12 grains, which provides reasonable single-kernel resolution.
The consistent primer seating depth note from the original article is valid and worth repeating: use a quality bench priming tool like the Forster Co-Ax Bench Priming Tool or K-M Primer Deluxe Hand Priming Tool to seat magnum primers to consistent depth. Primer seating depth variation introduces ignition inconsistency that undermines the precision that careful charge weighing achieves.
Primers
Magnum large rifle primers are mandatory for Alliant Reloder 33. Standard large rifle primers are insufficient for reliable ignition of 90-105 grain charges of ultra-slow powder in large-capacity cases. Standard primers do not deliver enough brisance to ignite the full powder column consistently across all temperature conditions. Hangfires and incomplete ignition events from standard primers in ultra-slow powder applications are not theoretical concerns – they are field-reported occurrences.
| Primer | Type | Application |
|---|---|---|
| Federal GM215M | Large Rifle Magnum Match | Gold standard for precision ELR loads |
| CCI 250 | Large Rifle Magnum | Reliable all-weather ignition |
| 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 | Heavy charge reliability |
| RWS 5337 | Large Rifle Magnum | Premium European precision option |
| Fiocchi Large Rifle Magnum | Large Rifle Magnum | Consistent alternative |
| Ginex Large Rifle Magnum | Large Rifle Magnum | General magnum use |
The Federal GM215M is the most commonly cited primer in competitive 338 Lapua Magnum loading with Reloder 33. Its match-grade brisance tolerances and the reliability of Federal’s magnum primer line are well-documented in long-range precision competition.
Primer seating depth matters more with ultra-slow powders than with faster ones. A primer seated 0.003 inches shallower than another ignites with less initial energy transfer because the anvil compression is different. In a fast-burning powder where ignition energy far exceeds the minimum required, this is a minor variable. In a slow powder at the edge of the ignition envelope, inconsistent primer seating depth shows directly in velocity spread numbers. Use a quality priming tool and verify seating depth consistency with a case gauge.
Reloading Safety Notes
Alliant Reloder 33 operates at charge weights in the 90-105 grain range in primary applications – among the largest sporting rifle charges in common use. Pressure management at these charge weights requires particular discipline.
The case fill target of 95-102% means some loads will be at or slightly beyond 100% case fill – in the light compression zone. Compressed loads require attention to seating consistency. Bullet seating force must be consistent between rounds; variable seating force on compressed powder charges introduces charge density variation that affects ignition behavior.
Start 10% below the listed maximum and work up in 0.3-grain increments. In 338 Lapua at maximum Reloder 33 charges, pressure can approach the case and action limits quickly. Stiff bolt lift is the primary early pressure indicator; watch for it before primers show other signs.
All charges must come from current published Alliant load data for Reloder 33 specifically. Do not use H1000 or Retumbo charge weights as a starting reference – the density and energy differences are too large for safe interpolation.
See the overpressure in reloading guide for systematic pressure sign identification.
The single-base vs. double-base powder overview explains why Reloder 33’s double-base chemistry produces its performance characteristics and temperature sensitivity relative to single-base alternatives.
FAQ
Can Reloder 33 be used in 338 Winchester Magnum?
The 338 Winchester Magnum has a significantly smaller case than 338 Lapua Magnum. Reloder 33 is too slow for the 338 Win Mag case at standard 225-250 grain bullet weights – combustion is incomplete, standard deviations are poor, and efficiency is lost. Powders in the H4831/Reloder 22 burn rate range are appropriate for the 338 Win Mag. Reloder 33 belongs in the 338 Lapua and larger cases.
What is the minimum practical barrel length for Reloder 33?
27 inches is the practical minimum, with 28-30 inches preferred. In a 24-inch barrel, expect poor standard deviations, excessive muzzle blast from incompletely burned powder, and reduced velocity relative to what the powder’s potential should deliver. Reloder 33 is not a short-barrel powder.
How does Reloder 33 compare to N570 in 338 Lapua?
Both are double-base slow-magnum powders for 338 Lapua with heavy bullets. N570 has a strong reputation for accuracy and consistency in European competition and typically costs more per pound in North America. Direct velocity comparison depends on specific loads and barrels. Both deserve load development evaluation; direct chronograph comparison in your specific rifle is the most reliable guide.
Is the temperature sensitivity of Reloder 33 manageable for hunting?
For most hunting scenarios – shots within 500 yards, temperature swings of 30-40°F – the velocity variation is manageable with an adjusted drop chart for conditions. For extreme long-range hunting at 800-1,200 yards where temperature variation substantially affects trajectory, a more temperature-stable powder like H1000 or Retumbo is the more practical field choice. Reloder 33 is optimized for the ELR competition environment where precise conditions are known and compensated for, rather than the variable field hunting environment.
Conclusion
Alliant Reloder 33 is an uncompromising specialist. Its ultra-slow burn rate, perforated cylinder geometry, and extreme bulk density exist for one purpose: maximum velocity from the largest practical sporting rifle cases, specifically 338 Lapua Magnum with 285-300 grain bullets and 300 Norma Magnum with 215-230 grain projectiles in long-barreled precision rifles. In those applications, nothing else on the market achieves what it does.
Outside those applications, it is the wrong tool. Standard magnum cartridges, shorter barrels, lighter bullets – all of these take a powder that is the best at what it does and force it into a role where its burn rate produces incomplete combustion and poor consistency. The specificity is the point: Reloder 33 does one thing and does it better than any alternative.
Choose Alliant Reloder 33 if you shoot 338 Lapua Magnum with 285-300 grain bullets or 300 Norma Magnum in a purpose-built long-range rifle with a 27-30 inch barrel, and maximum muzzle velocity is the primary objective. Choose Hodgdon H1000 if temperature stability across seasonal extremes and Extreme series reliability are more important than peak velocity. Choose Alliant Reloder 26 if your primary cartridge is 300 Winchester Magnum or 7mm Remington Magnum where Reloder 33 burns too slowly. Choose Hodgdon Retumbo if 300 PRC or 300 RUM at moderate bullet weights with Extreme stability is the goal.
Editorial note: Originally published 2026, revised April 2026. The revision added the dedicated section on perforated cylinder grain geometry and why it produces a progressive pressure curve, added a specific minimum barrel length requirement section with the consequences of shorter barrels explained, rewrote the temperature stability section with the ELR competition vs. field hunting context, corrected the 338 Winchester Magnum FAQ with the appropriate alternative powders, extended the bullet table with the specific warning against light bullets, added a dedicated primer seating depth note, added full internal links throughout, and added the reloading safety section with compressed load handling guidance.
