By Randy Garrett, American Handgunner
These Big Bore Bruisers Are Versatile, But Need The Right Ammo.
Have you ever wondered why .44 Magnum ammunition tends to be so much shorter than the revolver cylinders in which it’s chambered? Or why crimp grooves vary so much in their placement? These issues are of huge importance to the caliber’s ability to safely generate magnum power, and can be managed by the ammo builder to increase performance.
Since the obvious appeal of the .44 Magnum revolver is its ability to fire powerful ammunition, all component parts of the cartridge should contribute to the efficient generation of that power, so the desired performance levels can be achieved within proper limits of chamber pressure. Once the bullet has been selected, this tends to manifest itself primarily in carefully dispensed charges of an appropriate gunpowder.
However, there’s another ammunition “characteristic” playing as big a roll in determining chamber pressure, as does the gunpowder charge or bullet weight. That characteristic is the seating-depth of the bullet, or the distance from the crimp groove to the base of the bullet.
Factory guns, like this Smith & Wesson 629 (top), and custom guns, like this Ruger Bisley customized by John Gallagher, can both benefit from “bullet-forward” loading in the .44 Magnum.
A simple selection of tools and some common sense will really make your .44 Magnum revolver a much more versatile tool, keeping pressure under control and enhancing shootability.
Seating Depth
Magnum cartridges have larger capacity cartridge cases so they can hold more gunpowder. Any time the capacity of a cartridge case is increased, more gunpowder can be added, allowing higher velocity at the same chamber pressure. Significantly, not all bullets of equal weight and diameter exhibit equal amounts of seating-depth, and seating-depth determines the exact volume of the gunpowder space in the cartridge case. Consequently, if the ammo builder selects a bullet that doesn’t seat as deeply into the cartridge case, he can increase the amount of available gunpowder space, and get the benefit of a larger charge of gunpowder.
This can increase velocity, usually, without increasing chamber pressure. Simply stated, “shallow-seating” bullets allows higher velocity at the same chamber pressure, since more gunpowder can be used. It also allows the same velocity at reduced chamber pressure. By contrast, “deep-seating” bullets generate higher chamber pressure if the velocity is held constant (due to less gunpowder space), or, reduced velocity if chamber pressure is held constant.
SAAMI has established a maximum cartridge length of 1.60″ for the .44 Magnum, and that spec is commonly adhered to by component manufacturers and ammo builders. Because of that, we tend to have unnecessarily short ammo for use in revolvers, with their long chamber throats. This is done so the same ammo can be used in a variety of firearm types, such as magazine-fed autos and various rifles.
Yet this practice clearly decreases the amount of power that can be safely generated from the revolver. But does guarantee if you have a firearm, any firearm, chambered in .44 Magnum, it will properly chamber the ammo. This is an unfortunate circumstance, as the .44 Magnum is overwhelmingly a revolver caliber, and benefits greatly in its ability to safely generate power when shallow-seating bullets are used.
A S&W Model 29 from their Classic Series. When reintroduced, their popularity showed shooters are still clamoring for high-performing .44 Magnum revolvers.
Photo: Ichiro Nagata
Three loads using 300-gr. Bullets. Notice the big difference in cartridge length. Left is Federal 300-gr. Cast-Core (seating depth: .500″), middle cartridge is a handload using the Hornady 300-gr. XTP JHP (seating depth: .400″) and on the right is Garrett Cartridges of Texas 310-gr. Hammerhead Ammo (seating depth: .400″).
Great Efficiency
The selection of shallow-seating bullets is a responsible step toward producing greater efficiency in the .44 Magnum revolver, but is not a suitable choice for use in other firearm types, such as rifles or magazine-fed autos. For those firearms, SAAMI length-compliant ammo is the only choice. Also, exceeding SAAMI recommended chamber pressure guidelines can be a very dangerous practice and should not be attempted.
However, through the use of shallow-seating bullets, we can generate less chamber pressure per unit of energy, which allows us to reach our desired power levels with less chamber pressure. This is simply too much to ignore when building full-power ammo for the .44 Magnum revolver.
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