the ruger MK series isn't user friendly for a novice, unfortunately. Despite owning two of them, I can't recommend them for anyone that isn't mechanically inclined, let alone firearm friendly. I'd put money down that more "i just took it apart to clean it" guns-in-a-bag taken in to be reassembled by gunsmiths have been ruger MK pistols than any other. I haven't owned one, but from what i've read I'd say a buckmark is my next .22 handgun purchase
I've worked as a mechanical designer for about three years, have worked as a mechanic for well over a decade. So, I'm not exactly a newbie at working on stuff, or understanding how things go together. That being said... I was pretty confused until I got the right
youtube video.
The trick is to manage the position of the hammer and the strut that goes into the spring assembly. Do a search for vids with "ruger", "dingleberry" and "cheese"...
The hammer has to be in the 'down' position, out of the way of the bolt, when you put the upper onto the lower receiver. Then, you put the barrel of the gun pointed down, and pull the trigger, which lets the hammer come up/forward, bringing the strut (aka "dingleberry") up. Then, the stud that goes thru the upper receiver and holds it in place can be put in, and the spring assembly put 'mostly' back into the grip. Holding the gun with the barrel now pointed up, and the spring assembly rotated out about 1/2" on the bottom, pull the trigger. You should hear a faint 'click' as the "dingleberry"... uh... hammer strut, falls into place in the top of the spring in the spring assembly. If you did it right, you'll feel a tiny bit of spring load resistance as you push the spring assembly that last 1/8" into position and flip the little catch lever. If it just falls in, then the dingleberry isn't in the spring, and you won't be able to pull the bolt all the way back.
Once you get the hang of it, you can look like a hero to someone from time to time. Unless you find out the hard way that his '49 Ruger Standard's recoil spring assembly
didn't come with the guide rod peened over at the end, which would allow the recoil spring to fly off when you field stripped it to investigate a jam. At the busy gun range.
But, at least I... uh, err.. the guy at the gun range... was able to get the recoil spring assembly parts rounded up and the gun back together.
But, I've never regretted buying my Ruger, and would recommend one to anybody. Just plan on spending an hour or two getting used to that little trick.
-Bill