This handy accessories are $150 from Jonathan Arthur Ciener Firearms. A Yahoo search will turn up Jon's site. These .22 units have sold in the hundreds of thouands since their advent in 1976. This gives the lie to those who claim a lack of accuracy and/or reliability. Sure, some of them have problems, so do lots of 1911's and other guns. A decent smith easily fixes those problems, however, and they are not commonplace at all.
The .22 unit weighs less than 1 lb, and the caliber swap takes less than 20 seconds. All you have to do is remove the mag, empty the chamber, pop out the (held-captive) rear takedown pin on the receiver, remove the bolt, snap in the .22 unit, close the receiver, snap in the .22lr mag, and cycle the bolt. Voila, a loaded .22lr, where what you had before was a loaded 223. The reverse-converssion is just as handy.
This makes it feasible to always have the choice of either the very quiet subsonic .22lr, or even CB Caps, or the 10x greater power, 5-6 greater effective range of the 223 (vs that of the .22lr). With good softpoint loads, the 223 is as capable of taking deer as the longtime favorite 30-30, to similar ranges, with the caveat that you should never aim at the shoulder, nor take a rear angling shot. The 223 softpoint doesn't have the power needed for smashing the shoulder bone, nor the 2 feet (in flesh) of penetration needed for rear angle shots.
However, deer season is a very small part of the year. Most states lack populations of bear, elk, or moose, too. So the fun of a rifle, most of the year, lies in taking small game or varmints. The .22lr is a bit short of range and power for coyotes, fox, and bobcat, or feral dogs, for that matter. Guys like to shoot chucks, crows, and prairie dogs at 200 yds and more, but in many areas, at least some of the time, a quiet, subsonic .22 rd is more to the point. With the AR and a .22 unit, you have the option of either sort of shooting.
Furthermore, the AR wins the Highpower Rifle matches (beating even the bolt actions, especially at the 600 yd line). The AR's also win the "combat-style" rifle matches. The .22 unit lets you effectively practice your snapshooting, for combat matches, self defense, and survival scenarios, for 10% of the cost of 223 ammo, and you will be welcome at the indoor range with your .22 unit. They won't let you shoot there with your centerfire rifle (and probably not with your shotgun, either).
The Ruger 1022, Marlin, etc, do not handle like any fighting rifle. Their sights, safeties, bolt locks, mag-releases, and so on are in different locations, with different means of working. The .22 unit in the AR has the exact same sights and controls as the 223 version. Therefore, practice with the .22 conversion directly translates into skill with the 223. A scope, trigger job, ambi-saftey, etc, added to the 223 AR is automatically also added to the .22lr unit. This factor alone can save you many hundreds of dollars. The 223, using softpoint ammo, has plenty of power for self defense, but its recoil is so minimal that anyone who is truly skilled with the .22 unit has no trouble doing really well with the 223.
You can assemble an AR, out of a Stag, RRA, or other stripped lower receiver and Model One Sales parts kit, for under $600. The RRA 2 stage drop in trigger job is $100 from Triple Break Products, and really helps your ability to hit (swiftly). The AR-15 is the most versatile longarm available (when you consider that merely adding a different upper receiver can add any one of a dozen or more calibers, to include the .45 Professional, which is 4000+ ft lbs).
For instance, you can have a .50 AE or you can have a 26"+, 1000 yd special, with a 1 in 6.5" rifling twist, for use with 90 gr bthp match bullets. You can have a 10" or shorter "pistol" barrel, or anything in-between. You can have submachinegun concealment and handling speed, or 1000 yd sniping capability, whichever you want, with the handiness of just changing upper receivers. Your familiarity with the controls and the handling qualities of the gun will not be lost, because such attributes remain the same.
