Alliant Reloder 25 stands as a cornerstone in the world of ultra-slow burning propellants, specifically engineered to maximize the performance of large-capacity magnum rifle cartridges. As one of the slowest powders in the Alliant catalog, Alliant Reloder 25 was developed to fill the gap between traditional magnum powders and extreme “cannon-grade” propellants. For reloaders working with overbore cases and heavy-for-caliber projectiles, Alliant Reloder 25 provides the high energy density and controlled pressure curves required to achieve elite velocities that faster powders simply cannot reach without exceeding safe pressure limits.
Executive Summary
- Main Application: Optimized for high-capacity, large-bore magnum cartridges using heavy projectiles.
- Key Advantage: Significant velocity increases in long barrels due to its progressive burn rate.
- Burn Rate: Very slow – situated just slightly faster than Hodgdon Retumbo and slower than Alliant Reloder 22.
- What This Guide Covers: This technical manual details the physical composition, temperature sensitivity, market comparisons, and load component selection for Alliant Reloder 25.
Best For: Long-range precision shooters and big-game hunters utilizing 7mm Remington Magnum, 300 Winchester Magnum, and 338 Lapua Magnum platforms.
Powder Description & Technical Profile
Alliant Reloder 25 is a double-base extruded propellant. By incorporating a specific percentage of nitroglycerin into the nitrocellulose base, Alliant has created a powder that offers a higher energy-to-weight ratio than many single-base competitors. This double-base chemistry is what allows Alliant Reloder 25 to maintain high velocities even in shorter magnum barrels, though it truly excels in 26-inch or longer tubes. The physical geometry of Alliant Reloder 25 consists of large, perforated cylinders. This perforated design is critical; as the kernel burns from both the outside in and the inside out, the surface area remains relatively consistent, providing a “progressive” pressure curve.
The expert “feel” of Alliant Reloder 25 is characterized by its sustained acceleration. Unlike faster powders that deliver a sharp, violent peak pressure shortly after ignition, Alliant Reloder 25 delivers a smooth, extended push. This allows the bullet to accelerate more efficiently throughout the entire length of the bore, reducing the felt recoil impulse while maximizing the kinetic energy at the muzzle. Because of its large grain size, Alliant Reloder 25 provides excellent case fill (loading density), which often results in superior ignition consistency and lower standard deviations in velocity.
Pros & Cons
- Pros:
- Unmatched velocity potential for heavy bullets in 7mm Remington Magnum and 300 Weatherby Magnum.
- High energy density due to double-base composition.
- Excellent case fill characteristics prevent erratic ignition in large magnum cases.
- Cons:
- Large extruded kernels can be difficult to meter through traditional drum-style measures.
- Double-base powders can exhibit more carbon fouling compared to modern clean-burning single-base alternatives.
- Not suitable for medium-capacity or standard cartridges like 308 Winchester.
Technical Characteristics
The technical profile of Alliant Reloder 25 highlights its role as a high-volume propellant. Its high density is specifically designed to work within the constraints of magnum brass, ensuring that the reloader can reach maximum charges without needing to excessively compress the powder column.
| Technical Property | Specification |
| Density (g/cc) | 0.950-0.965 |
| Burn Rate Category | Ultra-Slow Magnum |
| Grain Shape | Large Extruded Perforated Cylinder |
| Coating | Graphite Surface Treatment |
| Base Type | Double-Base (Nitroglycerin/Nitrocellulose) |
Temperature Stability & Burn Rate Analysis
While Alliant Reloder 25 is a high-performance propellant, reloaders should note its position on the temperature stability spectrum. Historically, double-base powders like Alliant Reloder 25 have been more sensitive to extreme heat than the “TZ” (Temperature Zero) or “Extreme” lines of powders. Users can expect a velocity shift of approximately 1.5-2.0 FPS per degree Fahrenheit. For most hunting applications within a 40-degree temperature swing, this effect is negligible. However, for extreme long-range competition, it is advisable to work up loads at the temperatures you expect to encounter during your match.
Stability Comparison Table
| Powder | Stability Rating | Technology |
| Alliant Reloder 25 | Moderate | Standard Double-Base |
| Hodgdon H1000 | High | Extreme Series Single-Base |
| Alliant Reloder 22 | Moderate | Standard Double-Base |
Powder Comparison
To accurately place Alliant Reloder 25 in the propellant hierarchy, it must be compared to its most frequent competitors. It sits in a unique niche, slower than the classic magnum propellants but not as slow as the “over-magnum” powders used in the largest Weatherby and RUM cases.
| Powder Name | Burn Rate | Density (g/cc) | Primary Cartridges |
| Alliant Reloder 22 | Faster | 0.935 | 270 Winchester, 30-06 Springfield |
| Hodgdon H1000 | Faster | 0.925 | 7mm Remington Magnum, 300 PRC |
| Alliant Reloder 25 | Subject | 0.950 | 300 Weatherby Magnum, 7mm STW |
| Hodgdon Retumbo | Slower | 0.920 | 338 Lapua Magnum, 300 RUM |
| Alliant Reloder 33 | Slower | 0.985 | 338 Lapua Magnum, 28 Nosler |
Performance, Metering & Equipment
One of the most significant technical hurdles when using Alliant Reloder 25 is its physical grain size. Because it is a large-grained extruded powder, it does not flow through traditional volumetric powder measures with high precision. The kernels often “crunch” or shear in the drum, leading to charge variations of 0.3-0.5 grains. For a precision magnum load, this variation is unacceptable.
- Metering: It is strongly recommended to use an electronic scale and dispenser, such as the RCBS ChargeMaster Link Digital Powder Scale and Dispenser or the Frankford Arsenal Intellidropper 2.0 Digital Powder Scale and Dispenser. These units dispense by weight rather than volume, bypassing the metering issues of large kernels.
- Fouling: Alliant Reloder 25 produces moderate carbon fouling. However, it burns very cleanly at higher pressures. If your cases are coming out with blackened necks, it is a sign that the pressure is too low for the powder to burn efficiently. Using a Frankford Arsenal Powder Trickler to reach exact target weights can help ensure every round burns with identical efficiency.
Recommended Cartridges and Applications
The primary home for Alliant Reloder 25 is in cartridges with a high case-capacity-to-bore-diameter ratio. These “overbore” cartridges require the slow, sustained burn of Alliant Reloder 25 to prevent pressure from peaking too early.
| Cartridge | Primary Application |
| 243 Winchester | Heavy 100-115 grain bullets for long-range varmint hunting |
| 25-06 Remington | Maximum velocity for 110-120 grain big-game projectiles |
| 6.5-284 Norma | Long-range target shooting with heavy 140-150 grain bullets |
| 270 Winchester | Specialized heavy bullet loads (150+ grains) |
| 7mm Remington Magnum | The gold standard for 160-175 grain hunting bullets |
| 300 Winchester Magnum | Heavy-hitting 200-220 grain long-range hunting and match loads |
| 300 Weatherby Magnum | Classic magnum performance for large African and North American game |
| 338 Lapua Magnum | Extreme long-range (ELR) shooting with 250-285 grain bullets |
Bullets
When loading Alliant Reloder 25, the best results are achieved with bullets on the heavier end of the caliber spectrum. Lighter bullets do not provide enough sectional density or resistance to allow Alliant Reloder 25 to reach its efficient operating pressure.
- Heavy 6.5mm: 140-156 grain projectiles.
- Heavy 7mm: 160-190 grain projectiles.
- Heavy 30 Caliber: 200-230 grain projectiles.
- Heavy 338 Caliber: 250-300 grain projectiles.
Primers
Igniting 70-100 grains of a very slow-burning powder like Alliant Reloder 25 requires a high-energy magnum primer. Standard large rifle primers often fail to provide the consistent “blast” needed to ignite the large powder column evenly, leading to hangfires or poor accuracy.
- CCI 250 Magnum Large Rifle Primer
- Federal 215 Magnum Large Rifle Primer
- Winchester WLRM Magnum Large Rifle Primer
- Remington 9-1-2M Magnum Large Rifle Primer
- RWS 5333 Magnum Large Rifle Primer
- Fiocchi Large Rifle Magnum Primer
- Ginex Large Rifle Magnum Primer
- Sellier & Bellot Magnum Large Rifle Primer
Expert Verdict
Alliant Reloder 25 remains one of the most effective tools for the magnum reloader seeking maximum velocity. While it requires modern electronic equipment for precise metering and careful primer selection for consistent ignition, the performance rewards are undeniable. In the 7mm Remington Magnum and 300 Winchester Magnum, Alliant Reloder 25 often delivers the highest muzzle velocities listed in manufacturer data. It is a specialized, professional-grade propellant that excels when pushed to its technical limits in long-barreled rifles.
Expert Pro Tip: When loading Alliant Reloder 25, always aim for a load that fills at least 90% of the available case volume. Low load density with ultra-slow powders can lead to inconsistent pressure spikes and erratic accuracy. If you are experiencing high velocity spreads, consider switching to a hotter magnum primer like the Federal 215 and ensure you are using a consistent seating depth. Utilizing a Forster Co-Ax Bench Priming Tool will ensure that your primers are seated to a uniform depth, which is the final step in mastering the high-volume magnum loads that Alliant Reloder 25 was built for.
