Published: 2026 | Last updated: May 2026
IMR 4198 is a fast-burning, single-base short-cut extruded powder from the IMR lineup, distributed by Hodgdon Powder Company. It was developed for small-capacity varmint rifle cases and large-bore straight-wall cartridges at low-to-moderate pressures – the specific application set where fast-burning single-base powders produce the best combustion efficiency and accuracy.
The powder shares the same fast-rifle application territory as Hodgdon H4198, which carries Extreme series temperature stabilizing additives. Understanding the relationship between the two is important: IMR 4198 burns slightly faster than H4198 and lacks the Extreme series deterrent coating. The original article correctly notes that H4198 “typically offers better temperature stability” – the Extreme series advantage is approximately 3-5x better seasonal stability (~0.3 fps/°F for H4198 vs ~0.5-0.8 fps/°F for IMR 4198).
Despite this limitation, IMR 4198 maintains a legitimate place in the lineup. Some shooters find it produces slightly higher velocities than H4198 from its faster burn position. It has a deep published data library in its application cartridges. And for reloaders who manage seasonal variation through verification rather than Extreme series stability, it is a fully capable fast-rifle single-base powder.
This article is based on published manufacturer specifications, established load data, and documented field reports. Specifications and performance figures can vary between lots, rifles, and conditions. If you have loaded IMR 4198 in practice – leave a comment below: real-world experience from the reloading bench is what separates verified data from manufacturer claims.
Powder Description and Technical Profile
IMR 4198 is a single-base, short-cut extruded powder. The single-base formulation – nitrocellulose without nitroglycerin – is the chemical basis for its clean-burning behavior and the moderate temperature stability that single-base chemistry provides compared to double-base alternatives at the same burn rate.
The short-cut grain geometry is the practical improvement over traditional long-stick extruded powders. IMR 4198’s grains are shorter than classic long-stick powders, reducing the bridging and shearing that full-length sticks produce in volumetric measures. This contributes to better metering than older long-grain powders at this burn rate position, though not at the ±0.1 grain performance of Hodgdon H4198’s very short-cut geometry.
Bulk density is approximately 0.850-0.880 g/cc – typical for single-base extruded powders at the fast-rifle burn rate position. The original article’s “High-energy density for its class” without a number is not useful for practical loading. At 0.850-0.880 g/cc, IMR 4198 provides near-complete case fill in 222 Remington at working charge weights – the consistent high case fill that contributes to the consistent ignition and low standard deviations that benchrest accuracy requires.
The “sharp” or “crisp” ignition description in the original article accurately reflects the fast-pressure-onset behavior of fast-burning extruded powders in small cases. In 222 Remington and 221 Fireball, this rapid pressure build-up produces near-complete combustion and clean barrel behavior before the bullet exits even shorter barrels.
Strengths:
- Fast burn rate specifically calibrated for small-bore varmint cases – 222 Remington, 221 Fireball, 22 Hornet – where combustion is complete and velocities are maximum
- 45-70 Government performance at Trapdoor and lever-action pressures – the large case at low pressure specifically benefits from a fast powder that produces adequate gas from a small charge weight
- Single-base clean burning – less carbon residue than double-base alternatives at equivalent pressures
- Good benchrest track record in 222 Remington competition where the fast burn rate, high case fill, and progressive pressure curve are specifically valued
- Deep published data library across the primary fast-rifle varmint and straight-wall applications
Limitations:
- Temperature sensitivity of ~0.5-0.8 fps/°F – standard single-base performance without the Extreme series coating; approximately 2-3x more sensitive than Hodgdon H4198 (~0.3 fps/°F Extreme). For varmint hunting across daily temperature swings, this is manageable. For year-round benchrest competition where seasonal zero consistency is essential, Hodgdon H4198 is more appropriate
- Short-cut extruded metering is better than long-cut but not at ball or H4198 levels – ±0.15-0.3 grain variance in standard volumetric measures; hand-weighing or auto-dispensing preferred for precision work
- 7.62x39mm semi-automatic gas system caution – the burn rate is at the slower edge for reliable semi-automatic cycling in AK and SKS platforms; Accurate 1680 is the more specifically documented powder for 7.62x39mm carbine use
- Not equivalent to Hodgdon H4198 – slightly faster burn rate and different temperature stability; charge weights are not interchangeable
Technical Characteristics
| Property | Specification |
|---|---|
| Manufacturer | IMR Powder (Hodgdon Powder Company) |
| Type | Single-Base Short-Cut Extruded |
| Bulk Density (g/cc) | ~0.850 – 0.880 |
| Grain Shape | Short Cylindrical |
| Coating | Technical Graphite |
| Burn Rate Category | Fast Rifle |
| Temperature Sensitivity | ~0.5-0.8 fps / °F |
IMR 4198 vs. Hodgdon H4198 – The Critical Comparison
The original article correctly identifies Hodgdon H4198 as IMR 4198’s “closest competitor” – but this relationship deserves more precise treatment than the original provides.
| Property | IMR 4198 | Hodgdon H4198 |
|---|---|---|
| Base Type | Single-Base | Single-Base |
| Grain Cut | Short-Cut | Very Short-Cut (shorter than IMR) |
| Burn Rate | Slightly Faster | Slightly Slower |
| Temperature Stability | ~0.5-0.8 fps/°F | ~0.3 fps/°F (Extreme series) |
| Metering | ±0.15-0.3 gr | ±0.1 gr |
| Series | Standard | Extreme |
IMR 4198 burns faster than H4198 – a commonly confused relationship from the shared name. The charge weights are not interchangeable. Applying H4198 charge weights to IMR 4198 would produce higher pressure than intended because IMR 4198 burns faster. Applying IMR 4198 charge weights to H4198 would produce lower velocity than intended.
For most applications where both powders have published data, the ballistic results are competitive – IMR 4198 may produce slightly higher velocities from its faster burn; H4198 produces approximately 3x better seasonal stability. The choice between them is primarily a stability vs velocity priority decision.
Temperature Stability – Practical Assessment
0.5-0.8 fps per degree Fahrenheit for IMR 4198 versus ~0.3 fps/°F for H4198. The practical difference across a 60°F temperature swing (cold morning to hot afternoon varmint session):
- IMR 4198: 60°F x 0.65 avg = 39 fps variation
- H4198: 60°F x 0.3 = 18 fps variation
At 300 yards on a prairie dog (4-inch target), 39 fps produces approximately 0.8-1.0 inches of vertical shift – perceptible and worth noting but not crippling for varmint hunting. At 400 yards, it becomes approximately 1.5-1.8 inches – meaningful for precision varmint work.
| Powder | 60°F Swing | At 300 yards | At 400 yards |
|---|---|---|---|
| Hodgdon H4198 | ~18 fps | <0.5″ | <0.8″ |
| IMR 4198 | ~30-48 fps | ~0.8-1.0″ | ~1.5-1.8″ |
| Alliant Reloder 7 | ~36-54 fps | ~1.0-1.2″ | ~1.8-2.2″ |
| Accurate 1680 | ~60-90 fps | ~1.5-2.0″ | ~3.0-3.5″ |
Burn Rate Comparison and Competing Powders
| Powder | Type | Density (g/cc) | Burn Position | Stability |
|---|---|---|---|---|
| Hodgdon H322 | SB Extruded | 0.895 | Faster | Extreme |
| IMR 4198 | SB Short-Cut | 0.865 | Reference | Standard |
| Hodgdon H4198 | SB Short-Cut | 0.865 | Slightly Slower | Extreme |
| Alliant Reloder 7 | SB Extruded | 0.880 | Comparable | Standard |
| Vihtavuori N120 | SB Extruded | 0.860 | Similar | Standard+ |
| Accurate 2015 | SB Short-Cut | 0.895 | Slightly Slower | Standard |
| Accurate 1680 | DB Ball | 0.960 | Slightly Slower | Standard |
vs. Hodgdon H4198: Covered in the dedicated section above. H4198 is the Extreme series choice at a slightly slower burn rate. For most shared applications, H4198 is the more seasonally stable recommendation. IMR 4198 is the choice when slightly higher velocity from the faster burn rate specifically matters and the shooter can manage seasonal variation through protocol.
vs. Alliant Reloder 7: Alliant Reloder 7 is a single-base extruded powder at a comparable burn rate with approximately 0.6-0.9 fps/°F sensitivity – similar to IMR 4198. Reloder 7 has deep 45-70 Government and small-bore data. Both are legitimate choices in shared applications; load development in the specific rifle guides the selection. Neither has the Extreme series stability advantage.
vs. Vihtavuori N120: N120 is a single-base extruded powder at a comparable burn rate – consistently praised for exceptional clean burning and Vihtavuori’s tight lot-to-lot consistency. Temperature stability is comparable to but typically slightly better than IMR 4198. For benchrest precision where cleanliness and lot consistency are the priorities, N120 is a legitimate high-end alternative. In the North American market, IMR 4198 is more widely stocked and has a deeper published data history.
vs. Accurate 1680: Accurate 1680 is a double-base ball powder at a slightly slower burn rate – specifically calibrated for 7.62x39mm and 300 Blackout subsonic applications. For 7.62x39mm in gas-operated semi-automatic platforms, Accurate 1680 is more specifically documented and better matched for gas system cycling pressure. IMR 4198 is more appropriate for 7.62x39mm in bolt-action precision use where gas port timing is not a constraint.
The 45-70 Government Pressure Tier Framework
The 45-70 Government has three distinct pressure tiers, and IMR 4198 load data must be matched to the correct tier for the rifle in use:
Tier 1 – Trapdoor Springfield (~14,000-20,000 PSI): IMR 4198 is published for Trapdoor-level 45-70 Government loads. Maximum charge weights for Trapdoor loads produce modest velocities with 300-405 grain bullets.
Tier 2 – Lever-Action Rifles (~28,000-40,000 PSI): Winchester Model 1886, Marlin 1895, and similar lever-actions with higher operating pressure limits. Some powders have separate data for lever-action pressures.
Tier 3 – Modern Strong Single-Shot Rifles (~50,000-60,000 PSI): Modern falling block actions (Ruger No. 1, Browning 1885). IMR 4198 is primarily documented for the lower two pressure tiers in 45-70 Government – verify from current published IMR data for the specific pressure tier and bullet weight.
Always identify which pressure tier your rifle falls into and use only published data developed for that tier.
Recommended Cartridges and Applications
IMR 4198 is most effective in small-capacity varmint rifle cases and large-bore straight-wall cases at low-to-moderate pressures.
| Cartridge | Bullet Weight Range | Notes |
|---|---|---|
| 222 Remington | 40-55 gr | Primary benchrest and varmint |
| 221 Fireball | 40-52 gr | Maximum velocity small-bore |
| 22 Hornet | 35-52 gr | Classic varmint small-bore |
| 204 Ruger | 24-40 gr | Fast varmint loads |
| 45-70 Government | 300-405 gr | Trapdoor and lever-action tiers only |
| 444 Marlin | 240-325 gr | Brush gun hunting |
| 30-30 Winchester | 110-130 gr | Very light bullets only |
| 7.62x39mm | 123-125 gr | Bolt-action precision only – see note |
222 Remington is the classic home territory – the burn rate is specifically matched to this case at standard 40-55 grain bullet weights. Near-complete case fill, consistent ignition, and a fast-pressure onset contribute to the low standard deviations that benchrest 222 Remington accuracy requires.
7.62x39mm note: Published IMR data exists for 7.62x39mm but Accurate 1680 is the more specifically calibrated powder for 7.62x39mm in gas-operated AK and SKS carbines. IMR 4198 in 7.62x39mm is appropriate only for bolt-action precision use where gas port cycling pressure is not a consideration.
30-30 Winchester note: The original article lists 30-30 Winchester as an application. IMR 4198 in 30-30 Winchester is appropriate only for very light 110-130 grain bullets where effective case volume reduction brings the burn rate window toward IMR 4198’s range. For standard 150-170 grain lever-action deer loads, IMR 3031 is historically better matched.
Bullets
IMR 4198 pairs best with light-to-standard weight varmint bullets in small-bore calibers and standard-to-heavy cast or jacketed hunting bullets in large-bore straight-wall cases.
| Brand | Model | Weight | Cartridge | Application |
|---|---|---|---|---|
| Sierra | MatchKing | 52-53 gr | 222 Rem | Benchrest Competition |
| Hornady | V-MAX | 40-55 gr | 222 Rem / 204 Ruger | Varmint Hunting |
| Sierra | BlitzKing | 40-55 gr | 222 Rem | Precision Varmint |
| Nosler | Ballistic Tip | 40-55 gr | 222 Rem / 22 Hornet | Varmint |
| Berger | Varmint Explosive | 40-52 gr | 222 Rem | Match Varmint |
| Hornady | NTX | 32-35 gr | 204 Ruger / 22 Hornet | Lead-Free Varmint |
| Barnes | Varmin-A-Tor | 36-50 gr | 222 Rem | Lead-Free Varmint |
| Hornady | InterLock FP | 300-405 gr | 45-70 Gov’t | Lever-Action Hunting |
| Hornady | LeverEvolution | 325 gr | 45-70 Gov’t | Modern Lever-Action |
| Sierra | Sports Master | 240-300 gr | 444 Marlin | Brush Gun Hunting |
Have you loaded IMR 4198? Your practical data on charge weights, accuracy in 222 Remington, 45-70 Government performance, or temperature behavior compared to H4198 helps other reloaders more than any spec sheet. Leave a comment below.
Primers
IMR 4198 as a single-base short-cut extruded powder responds well to standard small rifle primers in small-bore applications and standard large rifle primers for 45-70 Government and 7.62x39mm.
The original article’s note on CCI 34 for 7.62x39mm semi-auto is correct for the platform safety requirement (slam-fire prevention) – though Accurate 1680 is the more appropriate powder for that application.
| Primer | Type | Application |
|---|---|---|
| CCI BR-4 | Small Rifle Benchrest | 222 Rem benchrest – lowest SD |
| Federal GM205M | Small Rifle Match | Competition precision |
| Remington 7-1/2 | Small Rifle Bench Rest | 222 Rem classic benchrest pairing |
| CCI 400 | Small Rifle Standard | General small-bore development |
| Federal 205 | Small Rifle Standard | 222 Rem consistent ignition |
| Winchester WSR | Small Rifle Standard | General small rifle use |
| CCI 200 | Large Rifle Standard | 45-70 Gov’t, 444 Marlin |
| Federal 210 | Large Rifle Standard | 45-70 Gov’t general |
| Winchester WLR | Large Rifle Standard | Straight-wall hunting |
| CCI No. 34 | Large Rifle Magnum (Mil-Spec) | 7.62x39mm semi-auto – slam-fire prevention |
| RWS 4033 | Small Rifle | Premium European small-bore precision |
| Fiocchi Small Rifle | Small Rifle Standard | Volume production |
Metering and Equipment Compatibility
IMR 4198’s short-cut geometry meters better than traditional long-stick extruded powders – bridging is less common and shearing at the drum edge is reduced. Charge-to-charge variance of approximately ±0.15-0.3 grain is achievable on quality equipment, compared to ±0.3-0.5 grain for long-stick powders like IMR 4064.
The original article’s Pro Tip about using a long drop tube is specifically useful for near-maximum 45-70 Government loads where high case fill can make bullet seating difficult. A 6-10 inch drop tube allows the short sticks to settle under gravity before the bullet is seated, providing 2-4% more effective case fill without forcing a compressed load.
For benchrest and precision varmint loading in 222 Remington and 221 Fireball, the precision workflow eliminates volumetric variance: throw slightly under target weight with the Redding Competition 10X, then trickle to exact weight on the RCBS MatchMaster for ±0.02 grain charge consistency.
Reloading Safety Notes
All charge weights must come from current published IMR/Hodgdon load data for IMR 4198 specifically. Do not substitute Hodgdon H4198 charge weights – IMR 4198 burns faster and will produce higher pressure at H4198’s charge weights. Do not substitute Alliant Reloder 7 charge weights without independent verification.
[45-70 Government] pressure tier matching is mandatory. The three pressure tiers (Trapdoor, lever-action, modern single-shot) each require data developed for that specific tier. Trapdoor data cannot be used in modern strong single-shots and vice versa.
Temperature protocol: develop maximum charges at the highest expected firing temperature. At 0.5-0.8 fps/°F sensitivity, a near-maximum summer varmint load may show pressure signs in extreme heat.
Start 10% below the listed maximum and work up in 0.2-0.3 grain increments for small cases. Watch for flattened primers, stiff bolt lift, ejector marks.
See the overpressure in reloading guide for systematic pressure sign identification.
FAQ
Is IMR 4198 the same as Hodgdon H4198?
No. They share a name but have different burn rates, different temperature stability, and different charge weight requirements. IMR 4198 burns slightly faster than H4198 and lacks the Extreme series temperature coating. H4198 produces approximately 3x better seasonal stability. Charge weights are not interchangeable in either direction.
Is IMR 4198 good for 7.62x39mm in an AK-pattern rifle?
Accurate 1680 is the more specifically documented and calibrated powder for 7.62x39mm in gas-operated semi-automatic platforms. IMR 4198 in 7.62x39mm is appropriate only for bolt-action precision use. For AK/SKS carbine reliability, Accurate 1680 is the better-matched choice.
What is the advantage of IMR 4198 over H4198?
Primarily: slightly higher velocity from the faster burn rate in applications where both powders are documented. Some shooters find IMR 4198 produces better accuracy in specific rifles from the faster initial pressure onset. The trade-off is the Extreme series stability advantage that H4198 carries – approximately 3x better seasonal consistency. For year-round benchrest shooting where seasonal zero consistency is critical, H4198 is the more appropriate choice.
Conclusion
IMR 4198 serves its application range effectively – small-bore varmint cases where the fast burn rate produces maximum efficiency, and large-bore straight-wall cases at low-to-moderate pressures where the fast powder fills the large case efficiently at modest charge weights. The benchrest track record in 222 Remington is documented and genuine.
The temperature sensitivity (0.5-0.8 fps/°F) and the burn rate being slightly faster than H4198 are the operational trade-offs.
Choose IMR 4198 if you load 222 Remington, 221 Fireball, or 22 Hornet for varmint shooting or benchrest and want slightly higher velocity from the faster burn rate while managing seasonal variation through protocol. Choose Hodgdon H4198 if Extreme series year-round temperature stability is the priority in the same applications. Choose Accurate 1680 if 7.62x39mm semi-automatic or 300 Blackout subsonic are the primary applications. Choose Vihtavuori N120 if exceptional clean burning and Vihtavuori’s lot-to-lot consistency are the priorities for 222 Remington benchrest work.
Editor’s note: Published load data and manufacturer specifications are the starting point – not the final word. Field experience from reloaders who have actually worked with this powder is the most reliable guide to what it does in practice. If you have used IMR 4198, share your results in the comments.
Editorial note: Originally published 2026, revised May 2026. The revision added the specific bulk density figure (~0.850-0.880 g/cc) replacing the original vague “High-energy density for its class.” Added the dedicated IMR 4198 vs H4198 comparison table with the key clarification that IMR 4198 burns faster than H4198, not the same rate. Added the 45-70 Government three-pressure-tier safety framework. Corrected the 7.62x39mm application to bolt-action precision only with explicit Accurate 1680 recommendation for semi-auto carbines. Corrected the 30-30 Winchester application to very light bullets only. Added the temperature stability comparison table with 300/400-yard impact figures. Extended competitor comparisons to include Vihtavuori N120 and Accurate 2015. Extended the bullet and primer tables with full internal links. Added three community data disclaimer blocks in the correct blockquote format.
