Short History of the .451 Detonics Magnum

Various mechanical features of the Colt M1911 A1 auto pistol have prevented any significant ballistic advantage in the cartridges it chambers. One of these weaknesses is that a portion of the cartridge head is unsupported so operating pressures are dictated by the strength of that portion of the case. The 45 Winchester Magnum has a substantially stronger case head and dimensions identical to the 45 ACP except for greater length. In their search for a more potent 45 caliber round for their 45 caliber pistols, the Detonics Mfg. Co. decided to take advantage of this by trimming the 45 Winchester Magnum from its normal length of 1.198 inches to that of .942 inch. This is still sufficiently longer than the 45 ACP so that the 451 Detonics cartridge will not chamber in handguns intended for the 45 ACP. The newly created case will handle much higher pressures than the original 45 ACP and still function through actions of the same length. The idea of a more powerful 45 ACP cartridge has long intrigued 45 auto buffs. The 451 Detonics was a viable solution to what has heretofore been an insoluble problem. A 185 grain bullet at 1353 fps and a 200 grain at 1281 fps is a significant boost to the usual 45 ACP performance of a 230 grain at 850 fps. Recoil at this top loading gets rather heavy, so most users of the 451 will want to stay below the top loads. The 451 Detonics is a good self defense or field cartridge for small game or varmint shooting.*

Not only a powerful cartridge, the .451 Detonics Magnum can be very accurate. This is my 6 inch ScoreMaster shooting seven yards off hand, 8 shot group.  Final tuning on this gun was done by Peter Dunn, one of Detonics top factory gunsmith. 

The empty unprimed brass that Detonics sold was manufactured by Winchester with the "451 DET MAGNUM" headstamp.  The .451 D/M was a hand load proposition only. That was probably a big factor in the failure of the cartridge to entertain a large following. 

Overall length on the .451 D/M is the same as the less powerful 45ACP. The case is longer to prevent the .451 D/M from being able to chamber in a pistol designed for the 45ACP round.  The extra length does not afford more powder space due to the fact that the overall length has to remain the same as the 45ACP. So basically the 451 D/M bullet is seated deeper into the case which takes away any space gained by the longer case.

Photo copyright Allen Chinn used with permission.**

Two page memo written by Allen Chinn in 1983, which in part ask Detonics to pursue having "factory/commercially" produced .451 D/M. Allen, rightfully so, saw this as a roadblock to making the .451 D/M and it's guns more popular with the public. This, according to Allen, was never done. Take a look at this link for an example of a person selling factory ammo on GunBroker. Link-> Factory Ammo?
COR®BON Custom Post Production Ammo

This ammo was loaded  by COR®BON of Sturgis, South Dakota December of 1995. 
Note that they used 45 Win Mag cases and not actual .451 cases.
With a 200 gr JHP @ 1,200 FPS it's sounds like a pretty nice loading. 

The unprimed brass was packaged in either the MTM E50-45 (top) or the J50-45 (bottom) slip top boxes. My observation is that the J50-45 was by far the most widely used box.

Boxes for the brass had the "hand loaded ammunition" warning label under the lid.  I have yet to see evidence of any labels indicating commercially produced cartridges for the general public.

OEM box (top) label has die cut rounded corners following the MTM box contours. Reproduction box (bottom) has square cut corners and different font on the "A".

OEM (top) reproduction (bottom) showing different fonts used on each. 

*  Excerpt from "Cartridges of the World"
** Photo from "Combat Master, Sid Woodcock and Detonics" by Allen J Chinn

Updated 08.05.2012