The Ruger MKII pistols were made from 1982 until 2005. The MKIII series started in 2004. The major differences between the two pistols is that the MKIII has a magazine release on the left grip instead of on the butt of the grip; a loaded chamber indicator that sticks out if a round is chambered; and the MKIII has a magazine disconnect that will not allow a round to be fired unless a magazine is inserted in the pistol. The two "safety" features has raised a great deal of ire among the Ruger purists. They feel the pistols are "lawyered up" and either refuse to buy a MKIII or will change the MKIII hammer for a MKII hammer and use a bushing for the MKII to allow removal of the magazine disconnect. I don't think anyone complains about moving the magazine release.
In my opinion, the loaded chamber indicator is a waste of engineering and manufacturing costs. The early ones, I believe, were steel, and could result in firing a round if the LCI was struck sharply (for example, dropping the pistol). The later ones are not as hard and have removed the unsafe feature of the safety feature. I almost never look at the LCI. I assume there is a round in the chamber until I have visually checked the chamber by pulling back on the slide and looking into the receiver. Someone who is too careless to do that will probably not notice the LCI. I know Ruger had to do something like this to seel in California and other states, but it is a waste.
The magazine disconnect (the pistol will not fire unless a magazine is inserted) is a take it or leave it safety feature. For all the arguments pro and con, one should assume the pistol has a round chambered and it will fire if you pull the trigger with, or without, a magazine. This is firearm safety 101. The only difficulty with the magazine disconnect that I see is in disassembly of the pistol and reassembly. The mag safety lever fits on the hammer assembly and must be put in correctly for the pistol to function. For us fumble-fingers, it makes full disassembly (detail strip) a tad more difficult.
How does the safeties affect the firing of the pistols? I can't tell the difference. Both the MKII and MKIII are excellent .22 lr pistols. Both are well-made, easily upgradable with aftermarket parts, shoot consistently and accurately. Unless you want to shoot without an installed magazine, you can't tell the difference. I'm not sure what all the fuss is about.
