The .300 Holland & Holland Magnum has been around since 1925, and in over a century of existence it has been declared obsolete roughly a hundred times. Somehow it's still here — still being chambered by custom rifle makers, still being fired by serious hunters who know what they're holding. If you've inherited a .300 H&H, stumbled onto a used rifle in that chambering, or are simply curious about the cartridge that launched the American magnum rifle era, this guide will walk you through reloading it.

What the .300 H&H Magnum Actually Is

The .300 H&H operates from a 2.850-inch case with that distinctively long, gently sloping shoulder — 8.5 degrees, which is almost non-existent. This shallow shoulder was designed for reliable feeding in Mauser-action magazine rifles under field conditions, and it does exactly that. The downside is modest powder efficiency — you need a lot of case capacity to produce velocities that modern short-fat cartridges achieve more efficiently.

The upside is an extremely smooth feed cycle, excellent headspace control, and brass that lasts for many firings because the minimal shoulder means low work-hardening during sizing. Handloaders who case-form .300 H&H brass from .375 H&H stock report it feeds like a dream and lasts seemingly forever.

Maximum overall length is 3.600 inches, requiring a true magnum-length action — there's no shortcutting this one into a standard-length receiver. Factory SAAMI maximum average pressure is 54,000 CUP.

Brass Selection and Prep

New .300 H&H brass from Norma and Hornady is the most commonly available today. Norma is the quality standard — thick, consistent, and dimensionally excellent. Federal used to produce .300 H&H brass and you'll occasionally find it on the used market; it's serviceable but tends to be thinner and less uniform than Norma.

Full-length sizing is standard for .300 H&H. The minimal shoulder means neck sizing alone often produces headspace issues — full-length sizing every firing keeps things consistent. Use a quality sizing die from Redding or RCBS with appropriate case lube; the long, tapered case requires even lube coverage to prevent stuck cases.

Trim to 2.850 inches. Deburr, clean primer pockets, and uniform flash holes if you're loading for precision work. The .300 H&H doesn't demand the meticulous prep of a benchrest cartridge, but consistent brass prep pays off in velocity standard deviations at long range.

Primers

Large rifle magnum primers are mandatory. The .300 H&H's large case volume requires the hotter ignition of a magnum primer to ensure consistent powder ignition, especially with the slower-burning powders this cartridge prefers. Federal 215M, CCI 250, and Remington 9-1/2M are all excellent choices. The Federal 215M provides slightly more consistent ignition with the large charges of slow ball powders commonly used in the .300 H&H.

Powder Selection

The .300 H&H loves slow-burning powders. The large case volume and moderate pressure ceiling demand powders in the H4831/IMR 4831/Retumbo burn rate range to achieve full velocity potential without exceeding pressure limits.

• Hodgdon H4831SC: The most reliable performer across temperature ranges. Metered well, produces consistent charges, and delivers velocities close to theoretical maximum in most .300 H&H loads. The go-to for hunting loads where temperature stability matters.
• IMR 4831: Slightly faster than H4831, which allows slightly more case fill and often produces 25-50 fps additional velocity. More temperature-sensitive than H4831SC — not ideal for extreme cold hunting situations but excellent for range work.
• Reloader 22 (RL-22): Excellent with 180 and 200-grain bullets. Produces high velocities and prints consistently at long range. Temperature sensitive; use cautiously in situations ranging from -10°F to +100°F.
• Hodgdon Retumbo: Designed for large-capacity cases with slow-burning powders. Excellent with 200 and 220-grain bullets where maximum case fill is desirable. One of the best temperature-stable options for 200-grain hunting loads.

Bullet Selection for the .300 H&H

The .300 H&H's long action and moderate pressure ceiling make it particularly effective with heavy-for-caliber bullets. While 150-grain bullets are theoretically usable, they undersell the cartridge's strengths. The sweet spot is 180 to 220 grains.

• 180-grain Nosler Partition: The classic all-around big-game bullet for the .300 H&H. Adequate penetration for elk and bear at long range, controlled expansion for shoulder hits. At 2,880-2,940 fps from a 25-inch barrel, this combination reaches 300 yards with 2,200+ ft-lbs of energy — more than adequate for any North American game.
• 180-grain Swift A-Frame: Superior retained weight and penetration for close-cover bear and elk shooting. Sacrifices some BC for guaranteed expansion and deep penetration. Ideal for the coastal bear and elk hunting common in Oregon's wet, timbered country.
• 200-grain Nosler AccuBond: The modern premium bullet that showcases the .300 H&H's case volume advantage. High BC, bonded construction, and a muzzle velocity of 2,750-2,820 fps produces a truly flat-shooting long-range elk load. This is where the .300 H&H earns its reputation.
• 220-grain Woodleigh Weldcore: Old-school deep-penetrating controlled-expansion bullet for large, dangerous game. At 2,550-2,600 fps, it hits like a hammer and keeps going. Not a common choice for most Oregon hunting, but relevant for those taking the rifle to Alaska for brown bear or Canadian moose.

Load Data — 180-Grain Hunting Loads

Always start at least 10% below maximum and work up while watching for pressure signs. These loads are compiled from published sources and are presented as a starting point, not a finished recipe. Verify against a current reloading manual.

• Bullet: 180-gr Nosler Partition | Powder: H4831SC | Charge: 71.0 gr (start) / 75.0 gr (max) | Velocity: ~2,820–2,940 fps (26" barrel)
• Bullet: 180-gr Nosler AccuBond | Powder: RL-22 | Charge: 69.0 gr (start) / 73.0 gr (max) | Velocity: ~2,810–2,920 fps (26" barrel)
• Bullet: 200-gr Nosler AccuBond | Powder: Retumbo | Charge: 71.0 gr (start) / 75.5 gr (max) | Velocity: ~2,700–2,820 fps (26" barrel)

Performance in the Field

Hunters who have carried the .300 H&H to elk camps in Oregon's Wallowas or mule deer country in the High Desert consistently report the same things: the cartridge hits harder than the ballistics suggest, it recoils less than comparably powerful modern magnums (credit to that long, gradual powder burn), and it never fails to chamber cleanly even in gritty, cold conditions.

The .300 H&H Magnum won't out-shoot a .300 PRC on paper. It won't. But in the hands of a hunter who has worked up a carefully developed load with quality brass and a matched bullet, it remains entirely adequate for any big-game hunting Oregon or the broader West has to offer — and it does so with a history and elegance that no modern short-fat magnum can replicate.

If you have one, reload it. Shoot it. Hunt with it. There's a reason the old cartridges earn that title.