Solving Problems with .22-Caliber Conversion Units

Not long ago, I tested an Arcus Model 94, a 9mm pistol based on the Browning Hi-Power. The pistol is robust, accurate, and reliable, and as Chick Blood pointed out in his article in the November 07 issue, many Hi-Power parts, including magazines and grips, will fit the pistol just fine. But the Arcus’ slightly heavier frame’an advantage in hard use’would not accept a standard Hi- Power .22-caliber conversion. I remarked on this fact to a friend at the range and he replied: "The Colt is no better.

I have a .22-caliber conversion unit that won’t work on any of the seven 1911 frames I have tried it on. I didn’t pursue the matter further with my friend, but I couldn’t help but wonder what type of frames he was using. I doubt they were Llama or Star products but probably the Colt and Springfield and Kimber pistols I usually spotted in his hand on the range. Once again I consulted sheaves of notes dating back to the 1970s.

I carefully reconciled my experiences with his and as is sometimes the case the most pertinent experiences were the latest. As it turns out the .22 caliber conversions for the 1911 are neither troublesome nor trouble free. They simply require attention to detail. First, let me tell you why I think these conversions area good thing, and why the gunsmith should be familiar with them. Using inexpensive .22-caliber Long Rifle ammunition is an economical aid in marksmanship training.

Practicing without the distraction of recoil and the expense of centerfire ammunition’but on the same frame’is a considerable advantage. These conversions are great for breaking in new shooters. While there have been conversions made for other pistols including the German Luger, the best known is the Colt. Most of us are familiar with the original Colt .22-caliber conversion unit.

It uses a steel slide and a "floating chamber." Of course, convincing It works with GI-type 1911s and the Colt Series-70 pistols, but will require modification to work properly with the firing-pin block of Series-80 pistols. a steel slide to recoil with the momentum created by the little .22-caliber rimfire cartridge was a considerable problem to overcome. The floatingchamber concept reportedly owes much to the M1 carbine. The chamber actually acts as a type of piston that gives impetus to the slide in recoil.

I’ve heard it said that the floating chamber was used to simulate the

recoil of the .45 cartridge, but I don’t believe that. I’m pretty confident that the real reason this design was implemented was to give the slide a bit more momentum for surer cycling. The floating chamber is basically a model of piston power that jumpstarts the steel slide. The early versions are well made of good material. The Colt usually locks open on the last shot, which is not the case with many of the other units.

There have been reports of heavy leading of the chamber, causing malfunctions in as little as 50 rounds. The chamber will simply lead up and the piston movement is lost. The use of high-velocity .22 ammunition is required with the Colt unit, so it seems to me that rather than conventional leading there is actually some shaving of the bullet in travel. This results in a much "dirtier" action than other .22 pistols, the Ruger Standard Model or Browning Buckmark, for example.

But there are procedures that will help to eliminate or at least minimize this problem. By using modern high-velocity ammunition with plated bullets that did not exist when the Colt conversion was designed, function can be improved. For a variety of reasons, the hyper-velocity CCI Stinger ammo usually functions well, and will give up to 250 rounds before cleaning is mandated. The plated bullet is one reason, but the effect of the hypervelocity load is another.

I can’t prove it, but I think the bullet exits the chamber before the piston action occurs. This seems logical anyway. In any case, Stingers work great in the older conversions. Another issue we should discuss is cleaning. Chances are you’ve had an impossibly dirty conversion brought into your shop. Again, I can’t prove it, but I’m guessing that a Ruger automatic isn’t as dirty after 500 rounds as a Colt conversion is after 100. The conversion must be stripped and cleaned and cleaned some more.

Gun Scrubber works to loosen the chamber up, but then it’s elbow grease’and lots of it. The next procedure illustrates that we can’t be hopelessly tied to tradition or to purpose-designed gun lubricants. While they usually work as designed, in the field, I’ve used just about everything including a Chapstick to lubricate a balky handgun. The quality synthetics certainly work well, but at times experimentation is the key to innovation.

For example, I once carefully cleaned and stripped an original Colt conversion and used STP Oil Treatment to coat the chamber and piston. Believe it or not, coating the chamber and moving parts with STP greatly improved the function of the Colt unit, and reliability was extended to perhaps 300 troublefree rounds. Ammunition-related problems are common with these conversion units. Another reason the Stinger works is the ammunition is of high quality, originally designed to function well in automatics.

Lets face it, a lot of our customers will buy whatever .22-caliber ammo is cheapest, which may not be a problem with a revolver. If you test the strength of the crimp holding the bullet, you’ll find a wide variation among the domestic and foreign-made brands. Simply hold the cartridge between your fingers and wiggle the bullet. The crimp must be tight or the bullet will wriggle and will not feed and chamber properly in the .22 conversion. Lead will be shaved on feeding.

Once again, it’s up to the gunsmith to advise shooters to use quality ammunition. As for interchangeability, the original Colt unit works reliably with GI 1911s regardless of manufacture, the Colt Series-70, and most Springfield The S&W uses a firing-pin block that works off the grip safety; the Colt has a trigger-activated firing-pin block; and the Taurus uses anew version of the firing-pin block. All will work well with the Kimber or Ciener conversion unit.

The use of a lightweight aluminum slide allows it to function with .22 rimfire ammunition. This is the Platinum version, fitted with adjustable sights. Government Models. Although the conversion will fit the slide, it will not work properly with the Series-80s firing-pin block. You can get around this problem, however, without modifying the pistol. The lifter bar in the Series-80 simply needs a groove in the slide to ride in, which can be milled into the original Colt conversions.

This slight modification will not affect the performance of the unit on other Colt pistols. The GI .45s are well made and more consistent than many realize, and the Colt conversions seem to be of loose enough tolerances to fit most Colts, Ithacas, Remingtons, and Springfield pistols. Original magazines are no longer made, but Metalform produces a quality version of this once hard-to-find magazine. Accuracy with the Colt .22 conversion is not in line with a quality .22 target pistol.

It’s adequate and little more, although the CCI Stinger loads seem to produce better results than any ammo I’ve tried. If the shooter has a dedicated frame he wants to use for the .22 conversion and wants you to tighten it up, standard slide-tightening techniques work just fine with the Colt’s steel slide. Just be certain he plans to leave the conversion on that frame. Kimber pistols impress me, perhaps more and more as time goes by. Accuracy and reliability are excellent.

The frame rails and slide are purposely on the large end of specifications and tolerances, resulting in a good tight fit for a production pistol. This fit produces a pistol that may or may not accept a .22-caliber conversion unit. (Sometimes the slide is so tight it drags with a .22 conversion unit.) Conversely, Kimber’s own conversion unit fits all Kimber pistols and seems to fit all other 1911s well.

The first run of Kimber conversion units did not have the clearance cut for the Colt/Para-Ordnance firing-pin block, but the conversions Kimber makes now have this cut. The modern conversions such as the Ciener are made of aluminum. The Wilson Combat magazine is slightly more open, which seems to promote feeding reliability. The slide is light and recoils as a standard blowback, neatly solving the problems of convincing a heavy steel slide to recoil with .22-caliber energy.

These slides have proven durable and the Ciener in particular has proven to be accurate and reliable. Just the same, there are problems encountered occasionally. I will mention once more that, even with the aluminum-slide conversions, the most common malfunctions are ammunition related. Sometimes the slide is just a bit too tight on the frame. This results in drag that slows the cycle down. The only thing to do here is to polish the slide’ very carefully. Aluminum, of course, has different properties than steel.

With a too-tight slide and frame combination, I’ve filled the slide grooves with Brownells lapping compound and worked the slide slowly over the mating frame a couple of hundred

AMGFW08 AG DBI, Spread Ad (p/u from 11/07 issue)

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