I mentioned the Colt ACE 2 the other day and have been thinking about it on and off ever since. The ACE was an updated conversion slide , barrel and magazine for using a .22 long rifle. It was made to work with the series 80 guns. The original was the ACE and was originally thought up or training for the military. It had a system in it that made the gun recoil like it was firing .45ACp. A pretty neat trick. Not very much fun for shooting tin cans in the back yard but useful if you want to save money and have more ammo for training troops while making them experience the same recoil as the round they would actually fire in combat.

The ACE II did away with that since no one really wanted it. Even the military didn’t have that much use for it back in the day.

The first Ace was a conventional blow-back operated semi-automatic that outwardly resembled the gun adopted by Uncle Sam in 1911, but with the swinging link and locking lugs of the .45 replaced by a barrel pinned solidly into the frame by the slide stop. Other modifications included a 1/4″ shorter slide and barrel, a unique rim-fire firing pin and stop, ejector, and a stack of shock-absorbing washers under the barrel. These washers limited slide travel, necessitating relocation of the slide stop notch to suit the new .22-length action. Atop the slide sat the adjustable Ace sight, also unique to this model. This sight was developed at the behest of the U.S. Army, which was helping in the development of the Ace, and upon whose approval Colt depended for the promise of volume sales.”

Reports on the gun, both contemporary and modern, are a mixed bag. The pistol was beautifully fitted and finished in the manner of all pre-war Colts; and accuracy, from what amounted to a fixed-barrel pistol, was excellent. Of course, the Ace had the familiar feel of the .45, but there were problems associated with trying to operate a big-bore size pistol with the recoil energy contained in the .22 Long Rifle cartridge. With Colt’s own sleek, handy Woodsman on the market, the Ace’s popularity was never great, with either the commercial or military contingent; but the gun remained in production for about ten years.

Colt went back to the drawing board, to find a better way to adapt the small cartridge to the big pistol. If the pistol couldn’t be made to act small, maybe the cartridge could be made to act big. Enter David Marshall “Carbine” Williams, whose expertise in perfecting the short-stroke gas piston system would earn him his nickname after his design was incorporated into the mechanism of the wildly successful Ml Carbine. A variation of Williams’ principle, in which a separate “floating” chamber was itself the piston, allowed the recoil energy of the .22 cartridge to be boosted sufficiently to cycle a slightly modified .45 slide. Although this new Ace would still have many unique parts, it was very much more like the service pistol than the original one, so it would be called the Service Model Ace. It not only looked and operated almost identically to the .45, its new recoil-boosting design made it an even better trainer, causing Colt to tout it as an ideal companion to their new National Match .45. The Service Ace even included the new Stevens-pattern target sight as offered on the center-fire pistol.

The development of the Service Ace, with its fewer unique parts, allowed Colt to market a “conversion” kit of components that permitted someone already in possession of a Colt Government Model, National Match, or Super Match to swap the slide, barrel, spring and magazine for those in the kit, and have a .22 pistol. Conceptually, this was an even better idea than the Ace, as the .22-.45 Conversion Unit allowed retention of the all-important feel of the trigger of the parent arm. And since economy was the whole point of the exercise in the first place, having to buy only half a gun was an added attraction. The same idea, in reverse, did not work out so well, as the .45-.22 Conversion was a short-lived offering from Colt (In what has always seemed a confusing circumstance, Colt chose to name the Conversions in what would seem to be a counter- intuitive manner – the one converting the .45 to a .22 being the .22-.45 Conversion. If you take the meaning to be “a .22 from a .45”, it then makes sense). A few years after the introduction of the Service Ace and Conversion Units, the world was plunged into war, and all of Colt’s Aces were drafted into military service for the duration.

In 1949 the original Ace and Service Ace were no longer available, the last pistols having been assembled from parts produced during the war. The .22-.45 Conversion Unit however, was reintroduced to the commercial market, in slightly simplified form, and sporting a new rear sight – the Coltmaster. At that time, Colt ceased the serial numbering of the units, continuing to sell and catalog them throughout the 1950’s and ’60’s, although they were not always in production.


The ACE II was the idea brought back years later after Colt had stopped production of all other .22 rimfire pistols. The more expensive high quality semi autos couldn’t compete in the market with the cheaper ruger rimfire semi autos that seemed to rule the world at the time. And still do in the world of .22 pistols.

It was never a big seller and seeing them today is a rare thing. I have seen exactly 3 in 20 years of going to the National Gun day giant gun shows in Louisville, Ky and other smaller shows. Of course they can be found online but then again, so can anything.

1 Comment

  1. Matthew Whitticar says:

    I have a conversion kit. I bought years ago. My only complaint is that the followers are chewed up and they dont lock the slide back.

    Mine is pretty accurate and reliable.


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