Detonics was founded as a company in the 1970s, making high-end 1911 pistols. Their first product that really put them on the map was their 3" micro-compact 1911; something that just wasn't available on a production basis at the time. After the .45 Winchester Magnum cartridge was introduced in 1979, Detonics jumped at the chance to now make a higher-power .45 cartridge that would fit the 1911 magazine. Since the .45 WinMag brass was much thicker at the base than .45 ACP, Detonics was able to cut it down to ACP length (actually one millimeter longer, to prevent it from being chambered in a standard .45 ACP chamber). They then cranked up the pressure and were able to increase velocity by 30% over the original .45 - and they called the new round .451 Detonics Magnum.

Detonics made several different models of pistol in their new cartridge, both standalone guns, replacement slides for other frames, and package sets with both .45 and .451 barrels. They were never able to get an ammunition manufacturer on board though, and the .451 remained a hand loading proposition throughout its entire life. This crippled its chances at becoming mainstream, and it remains a very niche cartridge to this day. Its successors included the .45 Super and the .460 Rowland, which survive today but are definitely special-interest offerings.