For those of us who are still learning, can anyone tell (or preferably post a picture) us where exactly the metal washers go to shim the gas cylinder?  

Thanks in advance.

they go between the barrel shoulder and the front band.  

The barrel shoulder is that round ledge that the front band and gas cylinder rest against.

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Install the shim (s) until the cylinder lock indexes to the 3:oo hand tight (4:00 if only a single shim is needed), then use the lock wrench to finish index the lock to the 6:00 to allow the plug to be inserted.  The plug threads should be lightly grease, then backing up the lock with the lock wrench and torque the plug to 15 inch pounds (3/8" socket on a torque wrench).
Note: Fulton sels the shim kit (three shims) for $7.00.

As for the tools needed to shim a cyclinder, a FS castle nut wrench, the allen wrench to back out the FS set screw, a Lock wrench, and a 3/8" socket and torque wrench.  While your ordering parts, the drill bit set to clean the inside of the piston and plug are nice to have.

Also, if your going to all the effert to tighten up the cylinder, unitizing the front band to the cyclinder is worth the money.  Krieger offers the unitizing serves for less than $30, including recoating the welded area.

Dano,

Thanks for the post, that makes it a bit more clear to me.  Do you (or anyone else) know of any picture or diagrams showing the finished result?

You lost me,

On an AMU glued and screwed style front end, you don't see anything different.

If you mean the welded unitized job, the front of the clip will have three small Tig welds at the 10:00, 12:00, and 2:00 where the front hand guard clip is welded to the cylinder. Unitizing the two solves the problem of the clip moving from shot to shot on the barrel, hence changes in the downward barrel tension* if the front clip was not welded solid to the cylinder and allowed to move around on the barrel.
Note: shimming will help to tighten the two, but the clip can still slightly move from shot to shot, and unitized is the solid way to resolve the problem of changing barrel tensions.


* M-1 barrels need tension to shoot their best.  On the M-14, the tension is the front hand guard clip being pulled down as it interacts with the front stock clip.  On the Garand, the tension is upward from the contact with the middle band and the stocks front clip. Simple put, there is just way too much weight on the middle to front of the barrel such as cylinders and FS's and tension is needed to control the harmonic's of the end of the barrel.