Reloading Podcast 250 - I Feel the Need for Speed

Hello, and welcome to the Reloading Podcast here on the Firearms Radio Network.  

Tonight the guys are talking about a load going a mile a second.

  1. A mile a second, huh?

LFD Research

Project Appleseed

Cartridge corner: 300 Remington Ultra Magnum

.300 Remington Ultra Magnum


In 1913 Charles Newton introduced the world’s first high capacity .30 caliber cartridge, based on the 11.2mm Mauser cartridge necked down to .30 caliber. Newton’s cartridge was initially named the .30 Adolph Express after New York rifle builder Fred Adolph but later renamed as the .30 Newton. Case capacity of the .30 Newton was in every way similar to the modern 7mm, .308 Norma and .338 Winchester magnum cartridges however the Newton cartridge did not feature a belted case head. Unfortunately, Charles Newton was plagued with troubles in business. His cartridges never truly saw the light of day and with the introduction of the .300 H&H in 1925, the .30 Newton faded into history.

By the late 1980’s a more informed shooting public was now well aware that a powerful cartridge did not need a belted case. Belted cases may have been handy for wildcat case forming operations and indeed, the belted magnums had proven to be winners at 1000 yards. However the belt no longer served the purpose that it was designed for with the heavily tapered H&H cartridge designs and it’s more recent role as a marketing ploy, the belted case head had run its course.

The 1980’s saw Aubrey White and Noburo Uno of North American Shooting Systems (NASS), based in British Columbia Canada, begin the development of magnum capacity cartridges based on the .404 Jeffery’s Nitro Express. By 1995, basing his designs on the formed brass purchased from Noburo Uno, Don Allen of Dakota Arms had designed a full line of non belted 2.5” case length magnum proprietary cartridges for his Dakota rifles. At the same time, cartridge and rifle designer John Lazzeroni was developing a line of prototype cartridges which later became a line of both long 2.788” magnums and short 2.030” magnums.

In 1999 Remington released the .300 Remington Ultra magnum based loosely on the 404 Jeffery case design. The creation of the .300 Remington Ultra Magnum circumvented the proprietary status from the existing .404 based cartridges while spawning major competition with Winchester.  A main feature of both the Remington and Winchester magnums was a rebated rim, allowing these cartridges to work with existing magnum bolt faces. Remington's initial factory loading for the .300 RUM (discontinued) featured the 180gr Nosler Partition at an advertised 3300fps from a 26” barrel. These figures for the 180 grain bullet weight were later revised to 3250fps.

The .300 RUM quickly gained popularity with hunters throughout the western world. A powerful cartridge, producing impressively fast kills on light through to large medium game at close to exceedingly long ranges, this cartridge was for many, an introduction to the idea of long range hunting. Nevertheless, the .300 RUM was not without its idiosyncrasies. Excessive barrel wear, high operating costs, excessive recoil and other contributing factors put the .300 RUM into the same class as high performance race engines. For many hunters, these negative factors have become a major detraction. What was once a love affair with a potent .30 caliber magnum becomes a divorce within 600 rounds. Regardless of this, the .300 RUM is still enjoyed for its strengths by a wide range of hunters with differing needs and will most likely continue to retain a great deal of popularity for decades to come. Of the small bores, the .300 RUM is a true powerhouse.


The strengths of the .300 RUM can be found in its ability to drive long, heavy .30 caliber projectiles at immensely high velocities. The RUM can launch 180 grain bullets at over 3300fps and 200-210 grain bullets at 3100fps and faster.  This power can essentially be utilized in two ways.

On large bodied medium game weighing around 90kg (200lb) and up to 400kg (880lb) and using controlled expanding projectiles, the .300 Rum can be utilized to deliver extremely traumatic wounding within ordinary hunting ranges, effecting the fastest possible, humane kills.

Using long for caliber, fast expanding or frangible projectiles, the .300 RUM can be used as a highly effective long range hunting cartridge for all game up to maximum body weights of around 400kg (880lb).   

The ability to produce fast killing on medium to large bodied game weighing between 90kg and 320kg (200-700lb) gives the .300 (and other 300 magnums) an advantage over the 7mm RUM (as well as other 7mm magnums). The science involved is rather straight forwards once it is fully understood but requires careful consideration and study in order to achieve this understanding.

Ahead is a basic example and description of incidents of killing, comparing the 7mm RUM to the .300 RUM with relevant factors in chronological order:

150kg (330lb) deer.

7mm RUM (and magnum family).

Range inside 300 yards.

Conventional soft point (Interlock / Gameking), SST or A-Max of 160-162 grains.

Bullet impacts chest but meets so much resistance that not enough energy is available for the production of hydrostatic shock.

Animal stays standing or runs, time to death around 45 seconds.

Inspection of carcass reveals internal wounding was excellent, vitals destroyed.

150kg (330lb) deer.

300 RUM  (and magnum family).

Range inside 300 yards.

Conventional soft point (Interlock / Gameking), SST or A-Max of 180-208 grains.

Bullet impacts chest, produces hydrostatic shock, instant coma, followed by death.

Inspection of carcass reveals internal wounding was excellent, vitals destroyed

Please refer to the game killing section for more detailed information on the exact mechanics of hydrostatic shock, an often misunderstood term.

In the example just given, the .300 RUM produced immensely fast killing in comparison to the sevens. Nevertheless, this does not mean that the same 30 caliber projectiles will give the same results on light bodied deer. Regardless of the power of the .300 RUM, projectiles such as the 180 grain GameKing and Prohunter can produce delayed killing on light framed game by having too much momentum (bullet construction), not meeting enough resistance on impact, resulting in a lack of hydrostatic shock. As always, bullet weights and bullet construction must be matched to the job at hand. Again, referring to the example given, a change to the 160 grain Partition in the 7mm Magnum would have effected immediate collapse of the 150kg animal.

The .300 RUM most definitely has negative aspects. Excessive throat wear is a problem and can occur very quickly. If a rifle is shot in strings for practice, the early signs of accuracy loss can be seen in as little as 300 rounds. With care and attention to barrel heat, friction prevention and bore finish, optimum accuracy can be maintained for approximately 600 rounds. With great care, barrel life can be extended further, for up to 900 rounds. This 600 to 900 round figure is perhaps the most sound barrel budget, but again, bore care and shooting habits are key factors. With cleaning procedures, one could easily reason that the less abrasives used on an already fast wearing abrased bore the better. But the opposite is true, constant polishing prevents the barrel steel at the throat of the RUM’s from becoming porous.

Heated arguments do occur regarding barrel life of the RUM’s. Readers are in this regard asked to consider how such factors as lubricants, polishing methods, barrel steel, barrel contour and shooting strings can effect results. Yet another factor is how shooters define acceptable accuracy. While one shooter may find .75MOA acceptable, another may find this level of accuracy abysmal for long range shooting. When all of these factors are taken into consideration, one can see how easily barrel life results can vary from rifle to rifle and from shooter to shooter.

Remington utilize extremely long free bore to achieve high velocities in the RUM’s. This free bore acts as a gas expansion chamber, allowing for a long peak pressure wave. The .300 RUM uses up to .400” free bore, dictated by the available internal magazine lengths of typical magnum action rifles. In custom rifles, the magazines of the Winchester and Remington rifles can be altered to partially alleviate this potential problem thanks to the Wyatt Outdoors extended magazine box. But in standard form, the shooter can only experiment with ammunition and projectile brands and hope that a given projectile will enter the rifling squarely rather than off center and produce desirable accuracy.  

Generally speaking, the longer the projectile, the more it can be guided into the rifling squarely by the RUM case neck. Some rifles do produce desirable accuracy with lighter weight projectiles, experimentation and realistic expectations are the key.

A third negative factor of the .300 RUM is the immense recoil however this can be tamed via muzzle brakes. In unbraked rifles, a weight of 10.5lb field ready is about the minimum for which an experienced shooter can expect consistency of POI at long ranges, requiring sound shooting techniques and sturdy sling tensions as recoil inertia is still evident. Brakes for the .300 RUM should be side ported, rather than spiral ported, the latter having the potential to throw ground debris into the shooters face and across the rifle action unless a ground mat is used.

The velocities of the .300RUM can place extreme demands on projectiles, requiring stout construction for close range impact as well as fast expansion for longer range shots. The higher the impact velocity, the greater the target resistance, resulting in increased stress placed on projectiles. Again, matching bullet weights and bullet construction to game body weights and range is the key to success.

Like all .300 magnums, the .300 RUM is not designed for use on large dangerous game. When used on heavy game, as is reiterated throughout these texts, neck shots followed by head shots (head shots if range and conditions permit) produce the fastest, safest kills.

As with many cartridge designs, the .300 RUM has both its strengths and weaknesses. The trick is being able to understand and work to its strengths, exploiting the full potential of the available power. A high level of personal discipline is required to accurately shoot a stout recoiling magnum along with a sound rifle platform. To be sure, a .300 RUM rifle that groups 1.5” at 100 yards is far less effective in the field than a .308 Winchester that groups .5”.

300 RUM article


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