History & Design
The original Colt Ace was developed in 1931 as a trainer for the .45-caliber 1911. Even back then, .22 LR was more economical to shoot.
It had functioning problems, though, because the entire pistol – including the slide – was steel. This was meant to replicate the weight and feel of the traditional 1911, but the .22 LR round did not have enough power to consistently cycle the action.
Then, in 1937, the Colt Service Model Ace debuted. It featured a “floating” chamber that sits inside the barrel and acts like a piston. The floating chamber magnifies the .22 LR’s recoil energy, allowing the .22 round to cycle the heavy steel action reliably. It has the added benefit of increasing the felt recoil of the gun, so it more closely replicates shooting a .45 ACP 1911.
Related: Two Guys One Gun, Episode 4 – What's the Best Caliber for a 1911?
Now, don’t get me wrong – it’s nowhere as powerful as the .45 ACP round, but it is probably twice as strong as a typical .22 LR pistol.
Production
The Service Model Ace was produced through 1945, but after World War II, Colt ceased production. In 1978, Colt reintroduced the gun and produced it until 1982. My friend’s father’s gun is one of these models.
Using the serial number search on Colt’s website, I learned that this one was built as a complete Service Model Ace pistol in 1982, the last year of production.
The Service Model Ace was usually sold as a .22 LR trainer pistol only, but a separate .22 LR upper kit was produced to convert existing .45 ACP pistols into trainers. These were called Ace IIs.
This pistol came with an additional .45 ACP slide assembly. The engraving on the slide reads:
“Colt’s MKIV / Series ‘70
Government Model
.45 Automatic Caliber”
A few Service Ace units were sold with .45 ACP slide assemblies, allowing the .22 trainers to be converted to standard .45 ACP 1911s, since the frames were 1911 frames. However, these kits were quite rare. Since there is no serial number on the .45 ACP slide, I don’t know if this was one of those kits, or if my friend’s father obtained a .45 ACP slide from another source.
Features
As I said before, the frame is a standard steel 1911 frame of the era. There is a curved short trigger, traditional spur hammer, small single-side safety, and arched mainspring housing. There was a choice of two styles of grip panels in the box: checkered walnut and the larger horn grips. Both have Colt medallions.
The Service Model Ace slide, while made of steel and resembling the size and weight of a standard 1911 slide, is modified for the .22 LR round. The barrel uses a bushing for slide lockup, and a short guide rod and recoil spring plug. A lightened recoil spring is specific to the .22 slide, and the extractor is a separate milled steel piece loose within the slide.
Adjustable rear iron sights are paired with a milled front sight post. I’m told that one can tell the generation of the Service Ace by looking at the style of rear sight, but I’m not that well versed.
The .45 ACP slide is a match-style 1911 slide with big slab sides. Only two parts of the upper are reused when the .45 ACP slide is installed: the short guide rod and the recoil spring plug. The slide, barrel, bushing and recoil spring are dedicated to the .45 ACP round. Both slides are beautifully blued.
Performance
This .45 feels like a traditional 1911. The solid single-action trigger and heavy steel construction makes the .45 ACP satisfying to shoot. Accurate and reliable, it is everything one would expect from a Colt .45.
Even with the .22 LR slide, the Service Model Ace remained reliable and accurate, and I haven’t experienced a single malfunction.
Since the trigger, grip, and overall weight are the same as on the .45 ACP, everything feels the same (other than the recoil). That’s the real beauty of this trainer, as you are using the same frame, grip, and trigger when you practice. The more reps you get on any platform, the better you will be.
Of course, the kick is lighter on the .22 LR trainer, but because of the extra power from the floating chamber, this gun makes .22 LR more satisfying to shoot. I think it’s more fun than a normal .22 pistol because you don’t feel like you are shooting a baby gun.
GSG Trainer Comparison
You see, most modern-day 1911 .22 LR trainers are built with a straight blowback design. To account for the low energy of the .22 LR round, the slide is made of aluminum. My personal GSG .22 LR trainer is built this way. The slide is very light and moves easily, so shooting it feels like almost nothing.
As I said earlier, the recoil on the Colt Service Model Ace feels probably twice as strong as on the GSG. That’s just enough to make the recoil feel substantial, and it is a noticeable difference.
Now, if you want a pure .22 LR target pistol, then the additional recoil is probably bad. But if you are looking for a centerfire trainer that can give you feedback without all the cost of a centerfire round, the Colt Service Model Ace might be your answer.
Reliability
Accuracy-wise, these two guns are about the same, but the Colt has been much more reliable than the GSG. I’ve had very good luck running CCI mini-mags.
Unfortunately, .22 LR 1911 trainer pistols are notoriously unreliable, and my GSG has been consistent with that stereotype. No matter what type of ammo I use, I get malfunctions.
I will caution you that the Service Model Ace does not have a stellar track record, either. While the floating chamber does make it more reliable, that same chamber is supposed to be more susceptible to fouling. Owners are expected to clean this floating chamber often to keep it running well.
I have not yet experienced this type of failure. I’ve put 500 rounds through it so far without out any issues or cleaning.
Pros & Cons
Pros:
- Interchangeable slides for .45 ACP and .22 LR
- Floating chamber amplifies .22 kick
- 1911 grip, frame, and trigger
- Solid steel construction
- Feels like a 1911
- Two sets of handsome grips
Cons:
- Floating chamber must be cleaned often to avoid fouling
-
No longer in production
Conclusion
I really like this gun and overall design. I’m fairly knowledgeable in the modern .22 LR world and had never heard of a floating chamber. I’ve found the Colt Service Model Ace super fun and not fussy at all. I don’t know why no one is producing this anymore.
Colt does not offer any .22 conversion kits for its 1911s at present, and there are no existing rimfire models in the company's lineup.
As a .45 ACP 1911 training pistol, I think it does a better job than anything on the market right now.
