Folks who choose affordably priced compact 9 mm carry pistols usually buy them because they not only fit into their preferred carry systems but they also don't break the bank in the process. However, diminutive semi-automatics, especially those with double-action-only triggers, require plenty of practice to master. The 9 mm ammunition needed to keep these little pistols fed at the range is one of the least-expensive cartridges on the market today. But that doesn't mean it's cheap.
An effective way to cut ammunition costs at the shooting range is to invest in a .22 Long Rifle caliber conversion. The .22 rimfire's penny-per-round price tag evaporated long ago and it's still hard to find in some places around the country. However, as of this writing, practice-grade .22 is in stock with reputable dealers for around $0.08 per shot. The practice-grade 9 mm provided by the same suppliers is going for $0.22 per shot. Even if you’re paying the steep price of $0.15 per round for .22, there's still a significant savings—one you've worked your way through to the other side of 500 rounds or more.
I've worked with rimfire caliber conversions for larger platforms, including 1911 pistols and AR-15 rifles, and found them to be reliable and fun to shoot. However, I haven't seen much in the way of conversions for sub-compact, single stack 9 mms even though their popularity has skyrocketed over the last couple of years.
When I recently learned that a company called Twisted Industries (TI) offers .22 rimfire conversion kits for the Kel-Tec PF-9, I was quick to give them a call. I reviewed the PF-9 a few years ago and chose to keep the gun once the article was complete. I was hoping the TI kit would justify more trigger time with this particular pistol.
Headquartered in Merritt Island, Fla., Twisted Industries started out in 2003 as a garage-based father-and-son operation. Today TI is housed in a 6,000-square-foot facility filled with top-of-the-line mills, laser, lathes and more. The company's products include milled billet AR-15 Lowers, components for Ruger, Kel-Tec and SCCY firearms and, of course, conversion kits.
The basic PF9-22LR conversion kit includes a complete slide assembly and one magazine. The lightweight slide is milled from aircraft-grade billet 7075 aluminum, just like the company's AR-15 lowers. The factory standard slide finish options include Graphite Black, Coyote Tan (shown) or OD Green Cerakote. Other colors are available upon request for an additional charge.
The standard sight system is a typical 3-dot type with a fixed blade in front and a drift adjustable rear sight. For this review, I had the sights upgraded to the company's metallic PF9 Optic Sight Kit, with several fiber-optic rod colors to choose from. The sights arrived with a red rod in front and a pair of green rods at the back. A hex head screw allows the rear sight to be drifted for windage. 
Customers have a choice of ordering a 3.10" stainless steel barrel which fits flush to the slide or a 3.65" barrel with a 3/8-24 TPI threaded muzzle. The company provides a variety of muzzle accessories, including thread protectors, muzzle breaks and a selection of thread adapters for sound suppressors. The recoil assembly consists of a full-length polymer guide rod fitted with a single round wire recoil spring.
The PF9-22LR conversion magazines provided with the kit were an unexpected surprise. I thought the magazine bodies and followers would be molded from polymer since they are matte black and orange, respectively. Upon closer inspection, I learned that the magazine body consists of two interlocking plates milled from aluminum. The bright orange follower, also milled aluminum, is supported by a round spring that's fitted into the front of the magazine. Only the removable base plate is polymer.
Quite frankly, the relatively thick aluminum plates make these some of the lightest and sturdiest pistol magazines I've ever worked with. The follower does not extend above the magazine feed lips. As a result, the slide does not lock open on the last shot. The magazines do not drop free of the grip but must be manually removed while the magazine release is depressed.
The only real downside I've found to pistol conversions is that they leave you with a handful of small parts with no where to put them. TI neatly solves this problem with a custom carry case. The stiff foam interior is pre-cut to hold a single complete 9 mm PF-9 pistol, the .22 slide assembly and three additional magazines. A slot cut in the foam above the pistol space can be used to store muzzle devices. As a result, this handy case makes it easy to store, transport and convert the pistol back and forth in the field.
Installation of the TI caliber conversion follows the same simple, no-tools-required steps used for disassembling the PF-9 for cleaning. Remove the magazine and lock the slide back into the open position. Verify that the pistol is completely unloaded. Remove the assembly pin from the left side of the frame. Press the slide forward and off of the frame.
The bare frame is ready for the TI conversion. Slide the complete .22 slide assembly onto the frame and lock it in the open position. Reinstall the assembly pin, close the slide and insert the .22 magazine. That’s all there is to it. What is immediately noticeable is how much lighter the pistol is. Swapping out the factory part for the TI components shaves 3.5 oz. off of the PF-9's already-light 14.9 oz. unloaded weight. In fact, with a payload of 10+1 rounds of 40-gr. .22 LR cartridges and a LaserLyte Lyte Ryder laser sight installed, the pistol weighs just 13.4 oz., making it an ideal candidate for use as a trail gun or kit gun.
Speaking of Laserlyte, the company's latest version of the Lyte Ryder (UTA-FSL) universal rail mounted red laser sight was an ideal fit for this review, so I trimmed a bit of foam out of the TI case and added it to the pistol. The Lyte Ryder weighs just 0.71 oz. and fits most Picatinny compatible rails.
Pressing either the left- or right-side activation switches activates a steady-on setting for use as a laser sight. Pressing and holding both buttons switches the module to sound activation mode for use with Laserlytes laser trainer target systems. These handy little electronic targets are portable and require no ammunition at all. It should be noted here that TI advises against dry-fire practice with the .22 conversion. If you're going to use the Lyte Ryder training mode, switch the pistol back to the factory 9 mm slide before you begin.
At the range, the TI conversion was fed a wide variety of practice-grade and premium ammunition from several companies, including Aguila, CCI, Federal Premium, Remington and Winchester. Although the pistol experienced a couple of failures to feed, one failure to eject, and a bad primer among the least expensive bulk box loads, the TI conversion was not a finicky eater. I've had some small .22 pistols refuse to function with entire brands but this kit managed to get along with them all. I was confident enough in the kit that I gave the pistol a “slush” test. That means I ran a few magazines through the gun that were loaded with a random mix of cartridges of varying brands, quality and power levels. The pistol hummed right through the slush without any malfunctions.
It was interesting to note just how much the accuracy potential shifted with different loads for the benchrested formal accuracy testing conducted at 15 yards using the fiber optic sights. Since this kit is most likely to be used for practice at the shooting range, I stuck with practice grade ammunition. Remington's Golden Bullet 40-gr. plated lead round nose produced a best single group of 2.52" with an average of 2.68". Federal Premium American Eagle 38-gr. copper-plated hollow points yielded a best group of 2.06" with an average of 2.18". Aguila Interceptor 40-gr. copper-plated flat points were the best performers of the formal testing with the tightest group of 1.83" and best average of 1.91". 
The Twisted Industries PF9-22LR Conversion Kit offers a host of features for more affordable training with your Kel-Tec PF-9 pistol. It converts a pocketable defensive pistol into a light and handy plinker, field gun and training tool. This conversion passed what I think is the most important test—it ran reliably with a variety of .22 ammunition almost all of the time. You might have a malfunction from time to time with cheap ammo but that's to be expected with small rimfire pistols. I had no problems at all with the more consistent mid- and premium-grade ammunition. Stick to the better quality loads in the field and the PF9-22LR will make for an enjoyable traveling companion.
NRA Specifications
Conversion Kit Manufacturer: Twisted Industries
Model: PF9-22LR for Kel-Tec PF-9 9 mm Pistol
Action: Blowback-Operated Semi-Automatic
Caliber: .22 Long Rifle
Slide: Milled 7075 Billet Aluminum, Coyote Tan Cerakote Finish
Sights: 3-Dot
Barrel: 3.65" Stainless Steel, 3/8-24 TPI Threaded Muzzle
Magazine: 10-Round, Graphite Black Aluminum
MSRP: Plain Barrel $199.99, Threaded Barrel $239.99
PF9 Optic Sight Kit $44.99
PF9-22LR Magazines $34.99
PF9 and PF922 Gun Case $26.99
3/8-24 TPI Muzzle Brake $19.99
Sound Suppressor Thread Adapters $9.99
LaserLyte Lyte Ryder Universal-Fit Pistol Laser $120.95
