10mm Auto (a.k.a. 10mm Norma, 10x25mm)
1. General information. The 10mm Auto cartridge was developed in the early 1980s, with the intent of creating a cartridge that could out-perform .45 ACP without resorting to a handgun of impractical size. Outwardly, it consists of a .400 caliber bullet in an extremely strong, straight-walled case with a large pistol primer. Overall length is approximately the same as the .45 ACP cartridge, allowing it to be chambered in handguns of similar size and design. However, its ballistics far exceed anything that can be safely accomplished with .45 ACP.
2. Ballistic comparison. The standard .45 ACP load is a 230 grain bullet driven to approximately 850 feet per second, generating 350 foot-pounds of kinetic energy at the muzzle. This reproduces the military “hardball†load used by the armed forces. By using 165 gr. bullets loaded beyond standard pressure limits (“+P†loads), velocities can be raised to 1,250 ft/sec, increasing the KE at the muzzle to about 570 ft/lbs. In contrast, factory standard 10mm ammunition can launch a 200 gr. bullet at 1,200 ft/sec (640 ft-lbs), or a 180 gr. bullet at 1,320 ft/sec (696 ft-lbs). With judicious handloading, even these ballistics can be safely exceeded. And for those times when maximum ballistics are not called for, there are numerous loads available in 10mm that are “down-loaded†to .40 S&W-equivalent ballistics (e.g. 180gr at 950 ft/sec).
3. Ammunition Availability. Nearly all major ammunition companies continue to produce 10mm ammunition. In fact, a number of companies in recent years (Pro Load, Triton, Texas Ammunition) actually introduced NEW 10mm ammunition lines in response to shooter demand. While prices at the corner store remain high, smart shopping online allows you to procure 10mm ammo at or below .45 ACP prices.
a. CCI-Speer continue to make the relatively inexpensive Blazer practice load.
b. Cor-Bon sells a full line of 10mm ammunition. Their self-defense loads (135gr, 150gr and 165gr JHP) are advertised at somewhat below maximum 10mm ballistics, but their hunting loads (180gr soft point and 200gr penetrator) are truly hot stuff.
c. Federal sells several 10mm loads in their Hi-Shok and Hydra-Shok lines, as well as a cheaper practice load under their “American Eagle†line.
d. Georgia Arms sells very affordable 10mm practice ammo ($160/1,000 and $180/1,000 depending on the load), as well as hot “Shear Power Plus†loads using the excellent Gold Dot bullet.
e. Hornady sells several 10mm loads using their XTP bullet, including a fairly hot 180gr “full-power†load.
f. Pro Load sells premium-quality, full-power 10mm ammunition using the excellent Gold Dot bullet.
g. Remington/UMC produces an excellent practice load in 10mm, though it is generally expensive.
h. Texas Ammunition Company produces a full line of very hot “10mm Express†loads.
i. Triton produces an extremely hot (155gr at 1,400 ft/sec) QuikShok 10mm load.
j. Winchester continues to produce their excellent, powerful 175gr Silvertip load (175gr at 1,290 ft/sec).
