Published: January 2026 | Last updated: April 2026
Disclaimer: All load data referenced in this article is drawn from published reloading manuals. The 338 RCM operates at 65,000 PSI. Always begin 10% below published maximum charges and work up carefully. Large rifle magnum primers are required. Never exceed published maximums.
The 338 RCM (Ruger Compact Magnum) was introduced in 2008 alongside the 7mm RCM as part of Ruger and Hornady’s short-action compact magnum line. Both cartridges are built on the .375 Ruger case – Ruger and Hornady’s non-belted straight-walled-at-the-head case that provides large capacity in a standard bolt face – and both were designed specifically for the Ruger M77 Hawkeye Compact Magnum with its 20-inch barrel.
Where the 7mm RCM targets deer and elk hunters who want 7mm magnum performance in a compact package, the 338 RCM is aimed at the hunter who wants .338 bore authority – the kind of terminal performance appropriate for moose, large bears, and the toughest game in North America – in a rifle that weighs and handles like a short-action deer gun.
The result is a cartridge that pushes 225-grain bullets to 2,800 FPS from a 20-inch barrel – essentially matching the 338 Winchester Magnum with a 24-inch barrel from a shorter, lighter package. This is a meaningful ballistic accomplishment that comes from the .375 Ruger case family’s efficient short-fat design.
Technical Characteristics
| Characteristic | Value |
|---|---|
| Bullet Diameter | 0.338 inches |
| Case Length | 2.100 inches |
| Overall Cartridge Length | 2.840 inches |
| Case Capacity | ~72 grains H2O |
| Case Type | Rimless, non-belted |
| Parent Case | .375 Ruger (necked down) |
| Rim/Head Diameter | 0.532 inches |
| Max Avg Pressure (SAAMI) | 65,000 PSI |
| Typical Bullet Weight | 180-250 gr |
| Muzzle Velocity (200 gr) | ~2,950 FPS |
| Muzzle Velocity (225 gr) | ~2,800 FPS |
| Muzzle Velocity (250 gr) | ~2,650 FPS |
| Muzzle Energy (225 gr) | ~3,920 ft-lbs |
The .375 Ruger case family uses a straight-wall case head without a belt – truly rimless and non-belted. The head diameter of 0.532 inches requires a shell holder designed for the .375 Ruger/RCM family. Standard .473-inch large rifle shell holders and standard magnum (.532-inch belt) shell holders both have different geometries from the RCM’s head. Use a shell holder specifically designated for the 338 RCM or .375 Ruger family.
338 RCM vs 338 Winchester Magnum: The Core Comparison
The 338 Winchester Magnum is the dominant .338-caliber hunting cartridge, and any buyer considering the 338 RCM evaluates this comparison.
| Factor | 338 RCM | 338 Winchester Magnum | Notes |
|---|---|---|---|
| Action length | Short | Long | RCM fits compact short-action |
| MV (225 gr) | 2,800 FPS | 2,800 FPS | Essentially identical |
| Case design | Rimless non-belted | Belted | RCM simpler headspacing |
| Factory ammo | Limited (Hornady) | Excellent | 338 Win Mag far broader |
| Rifle selection | Limited (Ruger) | Excellent | 338 Win Mag far broader |
| Brass availability | Limited | Good | 338 Win Mag easier |
| Shell holder | .375 Ruger type | Standard magnum | Different holders |
The ballistic performance is essentially identical. A 225-grain bullet at 2,800 FPS from either cartridge produces the same terminal performance. The 338 RCM’s advantage is the short-action compact format in the Ruger M77 Hawkeye Compact. The 338 Winchester Magnum‘s advantage is availability of factory ammunition, brass, and rifles from multiple manufacturers.
For a buyer choosing from scratch, the 338 Winchester Magnum is the more practical choice unless compact 20-inch barrel format is specifically required. For a hunter who already owns the Ruger M77 Hawkeye Compact in 338 RCM, it is a fully capable and well-designed cartridge.
Recoil
At approximately 28-32 ft-lbs in an 8-pound rifle, the 338 RCM produces noticeably more recoil than smaller calibers but is comparable to the 338 Winchester Magnum in similar rifle weight.
| Cartridge | Recoil (ft-lbs) | Rifle Weight (lbs) | Notes |
|---|---|---|---|
| 300 RCM | 22-25 | 8.0 | Same case family; lighter bullet |
| 338 RCM | 28-32 | 8.0 | Full .338 magnum class |
| 338 Winchester Magnum | 28-32 | 9.0 | Similar; heavier rifle helps |
| 338 Federal | 22-25 | 8.0 | Short-action alternative; less recoil |
In a compact 20-inch rifle at 7.5-8 pounds, the 338 RCM’s recoil is noticeably sharp. A quality recoil pad is important equipment, and managing recoil becomes a practical concern for hunters who fire multiple shots in practice.
Ballistics and Field Performance
Trajectory
| Distance (yards) | Velocity (FPS) | Energy (ft-lbs) | Drop (inches) |
|---|---|---|---|
| Muzzle | 2,800 | 3,920 | -1.5 |
| 50 | 2,704 | 3,659 | +0.5 |
| 100 | 2,609 | 3,410 | +1.4 |
| 150 | 2,516 | 3,173 | +1.1 |
| 200 | 2,425 | 2,943 | 0.0 |
| 300 | 2,247 | 2,526 | -6.5 |
| 400 | 2,076 | 2,155 | -19.5 |
| 500 | 1,911 | 1,827 | -41.0 |
225-grain hunting bullet, BC 0.514, 2,800 FPS muzzle velocity. 59°F, sea level, 1.5-inch sight height, 200-yard zero.
At 400 yards the 338 RCM delivers 2,155 ft-lbs – adequate for elk. At 500 yards it is at 1,827 ft-lbs, above the threshold for moose-sized game at that distance. The cartridge’s practical large game hunting range is 400-450 yards.
Reloading the 338 RCM
Primers
Large rifle magnum primers are standard.
| Primer | Type | Application |
|---|---|---|
| CCI 250 | Large Rifle Magnum | Standard choice; reliable; widely available |
| Federal 215 | Large Rifle Magnum | Hottest standard primer; cold conditions; slow powders |
| Federal GM215M | Large Rifle Magnum Match | Precision loads; lowest SD |
| Remington 9-1/2M | Large Rifle Magnum | Dependable; hunting loads |
| Winchester WLRM | Large Rifle Magnum | Consistent; slow powders |
Cases
Hornady is the primary brass source; Norma produces 338 RCM brass when available.
| Brand | Notes |
|---|---|
| Hornady | Primary and most available; good quality; consistent |
| Norma | Premium quality; available from specialty dealers |
The .375 Ruger head geometry (0.532 inches) requires a shell holder specifically designated for the 338 RCM or .375 Ruger family. This is different from both standard large rifle holders (.473 inches) and standard belted magnum holders. Verify shell holder fit before beginning sizing operations.
Non-belted headspacing on the shoulder: bump the shoulder 0.001-0.002 inches for consistent headspace and reliable chambering. Trim to 2.090 inches after each firing. Anneal every 4-5 firings.
Bullets
The 338 RCM uses the same .338-inch bullet library as the 338 Winchester Magnum.
| Bullet | Weight | Type | Application | Notes |
|---|---|---|---|---|
| Nosler AccuBond | 200 gr | Bonded BT | Elk, large deer | Bonded for reliable performance at range |
| Hornady InterLock | 200 gr | SP | Deer, elk; economical | Traditional; proven; widely available |
| Nosler AccuBond | 225 gr | Bonded BT | Elk, moose; standard | Good BC; bonded; recommended for large game |
| Hornady ELD-X | 230 gr | Polymer Tip | Elk, moose at range | High BC; controlled expansion |
| Sierra GameKing | 225 gr | SBT | Elk, moose; general hunting | Accurate; reliable expansion |
| Nosler Partition | 225 gr | Partition | Elk, moose, bears | Maximum penetration; controlled expansion |
| Sierra GameKing | 250 gr | SBT | Moose, large bears | Heavy; deep penetration |
| Nosler Partition | 250 gr | Partition | Brown/grizzly bear | Top choice for dangerous game |
| Barnes TSX | 210 gr | Copper HP | Lead-free; tough game | Deep penetration; California legal |
Use bonded or partition-style bullets for elk, moose, and bears. At 338 RCM velocities, lightly constructed cup-and-core hunting bullets can fail before achieving adequate penetration on large animals.
Powders
The 338 RCM’s 72-grain case capacity and 65,000 PSI pressure ceiling put it in the medium-slow to slow burning range – the same territory as the 338 Winchester Magnum.
| Powder | Bullet Weight | Start Charge | Max Charge | Approx Velocity | Notes |
|---|---|---|---|---|---|
| Hodgdon H4831SC | 200-225 gr | 62.0 gr | 69.0 gr | ~2,870 FPS | Top choice for 200-225 gr; consistent; widely available |
| Hodgdon H4831SC | 225-250 gr | 60.0 gr | 67.0 gr | ~2,720 FPS | Good with heavier hunting bullets |
| Alliant Reloder 22 | 200-250 gr | 62.0 gr | 69.0 gr | ~2,830 FPS | Good all-around choice; consistent |
| IMR 4831 | 200-225 gr | 61.0 gr | 68.0 gr | ~2,820 FPS | Classic big-game powder; versatile |
| Hodgdon H4350 | 200-225 gr | 60.0 gr | 67.0 gr | ~2,830 FPS | Temperature stable; good with lighter bullets |
| Hodgdon H1000 | 225-250 gr | 63.0 gr | 70.0 gr | ~2,750 FPS | Best with heaviest bullets; consistent SD |
| Hodgdon Retumbo | 230-250 gr | 64.0 gr | 71.0 gr | ~2,710 FPS | Very slow; best case fill for heaviest bullets |
| IMR 4350 | 200-225 gr | 60.0 gr | 67.0 gr | ~2,840 FPS | Good with lighter bullets; versatile |
| Vihtavuori N560 | 225 gr | 62.0 gr | 69.0 gr | ~2,820 FPS | Premium consistency; precision loads |
| Accurate MagPro | 225-230 gr | 62.0 gr | 69.0 gr | ~2,800 FPS | Ball powder; good metering; consistent |
| Alliant Reloder 25 | 230-250 gr | 62.0 gr | 69.0 gr | ~2,730 FPS | Good with heaviest bullets |
| Norma MRP | 200-250 gr | 61.0 gr | 68.0 gr | ~2,790 FPS | Good consistency; natural pairing with Norma brass |
All charge weights are reference figures. Verify against current published Hornady, Hodgdon, Alliant, or a current reloading manual before loading. Begin 10% below listed maximums. Work up in 0.5-grain increments.
Hodgdon H4831SC is the default starting point for 338 RCM load development with 200-225 grain bullets. The same powder selection that works in the 338 Winchester Magnum is generally appropriate here, scaled slightly for the modestly smaller case.
Practical Hunting Applications
Elk
The 338 RCM with a 225-grain Nosler AccuBond at 2,800 FPS delivers 2,155 ft-lbs at 400 yards and 1,827 ft-lbs at 500 yards – adequate for elk at those distances with quality bonded bullets and precise shot placement. The compact 20-inch Ruger M77 Hawkeye Compact handles this load in a package that weighs approximately 7-7.5 pounds scoped – meaningful in timber elk country where a hunter carries a rifle all day.
Moose
With a Nosler Partition 250-grain at 2,650 FPS, the 338 RCM is capable on moose inside 350 yards. The .338-inch bore diameter and heavy bullet weight provide the penetration through heavy bone and muscle that moose require. Use broadside or clear quartering-away angles; the cartridge is capable but not over-powered for this application.
Brown Bear and Grizzly Bear
The 338 RCM with a Nosler Partition 225-grain or 250-grain is adequate for defensive bear situations and bear hunting inside 200 yards. For dedicated brown bear hunting in areas with consistent close-range encounters, the 338 Winchester Magnum in a heavier rifle provides better recoil management for rapid follow-up shots.
Conclusion
The 338 RCM accomplishes its design objective: .338 Winchester Magnum-class terminal performance in a compact short-action 20-inch barrel rifle. For Alaskan and heavy-cover North American hunters who want .338 bore authority without carrying a 9-pound long-action rifle through dense timber, the 338 RCM in the Ruger M77 Hawkeye Compact is a logical and practical tool.
Its niche status in 2026 is the same as the 7mm RCM: factory ammunition from Hornady in limited variety, brass available from Hornady and Norma, and rifles primarily in the Ruger M77 family. For a hunter building a new compact .338 magnum rifle, the 338 Federal in a short-action or the 338 Winchester Magnum in a standard long-action offer better component availability. For the hunter who already owns the Ruger compact and wants to handload for it, the 338 RCM is fully capable and straightforward.
For related reading, see 338 RCM ballistics, 338 Winchester Magnum complete guide, 300 RCM vs 300 WSM, and 338 Federal complete guide.
Disclaimer: All load data in this article is for reference purposes only. Verify all charges against current published reloading manuals before loading. Large rifle magnum primers are required. Never exceed published maximum charges. Always begin 10% below listed maximums and work up while monitoring for pressure signs.
Editorial note: This article was originally published in January 2026 and revised in April 2026. The revision added the .375 Ruger parent case architecture explanation distinguishing it from belted and rebated-rim designs, the 0.532-inch head diameter and shell holder requirement, a direct 338 RCM vs 338 Winchester Magnum comparison table across seven factors, corrected the ballistics table to 200-yard zero per site standard, a complete powder table with 12 powders and charge weight ranges, expanded bullet selection with 9 bullets and cup-and-core warning, recoil comparison including 338 Federal as an alternative, and honest niche positioning for existing owners vs new buyers.
