Pipper,
You're right about Mossberg's manuals. I had to go through mine about 10 times before I understood it.
The initial cleaning should be like a normal cleaning, perhaps a little more thorough. DON'T disassemble the trigger group.
-Remove the barrel by turning the thumbscrew counterclockwise (as you look at it from the front) until it's loose. Move the forend about halfway forward. The barrel should pop right out.
-Drive the trigger group pin (the one just above the trigger) through the receiver with a small punch. I find that hand pressure is fine; no mallet should be needed.
-Remove the trigger group by pulling out on the trigger guard. The lugs are at the front of the assembly, so the rear of the group comes out first.
-Remove the shell stop and extractor from the inside of the receiver. These are the two little strips.
-Move the forend until the bolt slide is lined up with the cuts on the inside of the receiver. The slide should come up and off the bolt easily.
-Pull the forend forward over the magazine.
-Push the bolt through the front of the receiver.
-Remove the elevator by squeezing it about halfway down its length.
Your gun is now field-stripped. Go about cleaning the barrel and guts like normal; I use an old nylon toothbrush and Hoppes #9 on all the internals. Give the trigger group a good once-over, but like I said, DON'T take it apart. I don't oil the guts unless I know the gun isn't going to be used for a long time (yeah, that's likely
).
Reassembly is a bit tricky.
-Install the elevator; the two posts on the outside of the elevator arms fit into the holes in the sides of the receiver.
-Push the bolt into the receiver, firing pin hole forward (duh). There's a little tang on the inside of the receiver; you'll want to push this down with one hand while inserting the bolt with the other. Slide the bolt about 2/3 of the way back.
-Install the forend. The arms want to go into two small slots on either side of the magazine. It'll take some wiggling to get them to go in. Position the forend so that the notches in the arms are lined up with the notches in the bolt.
-Drop the bolt slide in on top of the bolt. Again, it'll take some wiggling and alignment to get it. When you've got it right, moving the forend will move the bolt and slide together with no hangups.
-Place the shell stop and extractor into their slots in the sides of the receiver. You'll notice that the extractor has a post, like the elevator. This post fits into a hole; the shell stop is smooth. You can't put these parts in incorrectly, but getting them to stay put takes some practice.
-Insert the forward end of the trigger group under the lugs, and pivot the group down into the receiver. It should go in with very little resistance. Once the group is in place, push the pin through the hole in the receiver until it's flush with both sides. Again, this should only take finger pressure.
-Position the forend about halfway along its travel. Place the breech end of the barrel into the receiver, and screw down the thumbscrew on the end of the magazine. Finger-tight only; no wrenches!
Your gun should now be reassembled. The manual suggests a function check at this point. I rack the action a few times, checking for binding or odd noises. I then try to pull the trigger while the safety is on. If the trigger doesn't move, I take the safety off and dry-fire the gun.
I'm getting a digital camera next week. I'll take photos of all the steps and send them to you, if you like.
HTH.
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"Taking a long view of history, we may say that
anyone who lays down his arms deserves whatever he gets."
--Jeff Cooper