The MKIII 22/45 has a funky bolt latch system that is counter-intuitive at best, and downright frustrating and stupid at the worst. When the last shot is fired from the gun, the magazine spring pushes the magazine follower up onto the bolt catch lever, causing it to come up when the bolt moves to the rear. When the bolt starts to come forward, it gets caught by the bolt catch and stays locked to the rear. When the magazine release button is depressed, the magazine (without a magazine disconnect) drops free. You then insert a fresh magazine into the gun, but instead of just yanking the bolt back a bit to release the bolt catch (like a pistol should), you have to also reach up with your thumb and manually push the bolt catch lever down.
I did about a 90% detail strip of the fire control mechanism and magazine release button. Ruger shipped this pistol to me with just a ton of rust colored assembly lube, and no matter how many times I ran a Q-tip in the small spaces in and around the controls, I could not get all that crap out. It was crammed into every nook and cranny of this gun, caked on the detent springs, all over the safety, and just crudded up on the magazine release. Okay, fine. I get it. Most users would never strip their gun down far enough to lube those parts, so Ruger did it for them. However, I'm the kind of guy who will stop at nothing to make sure my gun is clean enough to eat from when I'm finished with it. Plus, all that greasy crap tends to act like a magnet for carbon, dirt, dust, lint, and all other stuff you do not want in your pistol.
Brakleen to completely degrease them. Non-chlorinated Brakleen is safe for metal components and won't hurt finishes. If you don't believe me, look at the active ingredients on a can of gun blast spray and then a can of Brakleen. They are the same and they smell the same. Brakleen cost 1/2 the price though. Okay, digression over. After completely degreasing the parts, I lightly rubbed some Break Free CLP on all the metal parts to protect them. I wiped off the excess so they appeared dry, but were still slippery. I then dabbed very small drops of oil onto springs, pins, and rotating/sliding surfaces. Then I reassembled the gun. Getting the safety back in was a pain in the @$$, but eventually, I figured out the sear spring orientation. Oddly enough, the sear spring on my gun is different than what is shown in the manual an on GunTalk's detail strip reassembly procedures.
If your bolt doesn't want to pull back, check to make sure the safety is off. If it still won't pull back, you probably didn't put the mainspring housing back in right. Take it out and do it right. If the hammer doesn't fall when you pull the trigger, make sure the weapon is cocked. For a more detailed troubleshooting tree, click here.
Now comes the moment of truth. Did the slingshot mod work? To do this, you first insert a magazine into the pistol and pull the bolt back. Don't touch bolt catch lever. The bolt, when released, should stay locked to the rear because the magazine follower and spring are exerting upward pressure on the bolt catch and this causes it to hold the bolt back.
Strip out the magazine. Now, without touching the bolt catch lever, pull the bolt all the way to the rear. You should note that the bolt catch lever will fall to the lower position due to gravity. Release the bolt and it should fly forward without bolt catch manipulation. It should also do this live with a loaded magazine because the follower won't be putting pressure on the bolt catch lever.
Over on Rimfirecentral.com, I've read that this mod doesn't work on some pistols. Due to variances in the plastic frame tolerance, your bolt catch lever may or may not rub against the frame. If the bolt catch rubs on the frame, it may not always fall when the bolt is pulled back, or it may not work at all. To remedy this, one method is to take a file and ever-so-lightly file away the metal part of the bolt catch that rubs on the frame. Don't remove too much. Don't bend the bolt catch because you could do irreparable damage to the frame. If you must modify anything, modify the bolt catch. It's a low cost replacement part from shopruger.com, but the frame isn't.
There are other methods of mitigating the issue as well, including putting modified coil springs, or toggle bolt springs in to force the bolt catch to remain down, but unless you are having problems with yours, or releasing the bolt with the gun upside down is a concern, simply let gravity do the work. My gun is unfired, and as such, the slingshot mod works about 75% of the time. It gets hung up a bit, but I'm not going to mess with it until I've got a few hundred rounds through it. If I still experience issues at that point, some modification may be necessary.
Today is the big day for this gun. My wife and I are going on a double date with some friends to the range, and then dinner. I bought two 100rd boxes of CCI Minimag 22lr ammunition for break-in and plan on bringing some Federal bulk ammo to use once the Minimag ammo is done. I will have a range report when that is done.