Lets get the safety issue out of the way. Make absolutely sure the gun is unloaded, both the chamber and magazine before proceeding with the disassembly. Before I tell you what you need to know about tearing apart your favorite 1866 or 1873 rifle or carbine there are some items that I want to get out of the way so we are all on the same page.
1) I am a shooter who has taken the time and effort to know how my guns work. I am not a certified gunsmith. These are basic instructions for taking apart the rifle for general cleaning. If you are not comfortable working on your guns, please contact a gunsmith.
2) Get a set of high quality gunsmith's screwdrivers before you disassemble anything. They will make your life much more pleasant because you are less likely to strip a screw and put a gouge across the finish of your firearm, or your hide.
3) Work in a place that has good lighting with few shadows. Keep a small flashlight handy for those hidden areas that need a little extra light.
4) Remove distractions, pets, kids, spouse, etc. from work area. Trust me there are few things more irritating than having your dog jump on you just as you take the lid off the Hoppes, or your loving spouse interrupting you in the middle of a critical step.
5) Make sure your work surface is solid with plenty of area to set aside parts, tools and other materials.
Relax, this isn't difficult, it's a learning experience. First, read all the instructions through to the end. Also study the parts diagram below. You will save your self more than a few headaches if you read this whole document before you begin work.
Set the rifle on the table with the barrel to the left and the lever toward you, loosen (but do not remove) the two lever spring screws. The top screw is for the RIGHT lever spring (92) and the lower one is for the LEFT Lever spring (93). (Note: This step is not needed for merely cleaning the 73)
Now turn the rifle on the side, so the loading gate is facing down - on the table. It is important that the back be supported on the table because when you take it apart, some parts may fall out.
Unscrew the lever screw (101) and the side plate screw (123). Use screw drivers that properly fit the screws - they are relatively soft and VERY easily messed up.
Note. The model 73 does not need the lever screw removed unless you need to remove the lever.
To remove the left (top) side plate after removing the two screws, you may have to use the side plate screw. Put the screw into the hole just enough to let the threads grip the edge. Hold the screw at an angle and use it as a lever to raise the back of the side plate.
With the side plate off, study the linkage. Notice that the left link assembly has the thinner portion towards the barrel and is held by three pins - one on each end and one in the middle. You won't be able to see the Lever Pin (107) that holds the lever to the linkages - and cycles the linkages (and therefore the breech block or bolt). The bolt then cocks the hammer.
Remove the (left) link assembly. The lever pin may stay in the right linkage, stay with the right linkage, or fall out.
Now you may remove the lever. (For the Model 73, you do NOT need to remove the lever for cleaning)
The right side plate may simply fall onto the table. Or you may have to lightly tap on the rear of it to release it from the frame. Be careful to watch if the right linkage and lever pin falls onto the table.
Turn over the rifle and, if the right linkage assembly hasn't fallen out, gently remove it. You may have to use a screwdriver or pliers to grab the assembly and remove it.
Look at how the Lifter Arm (90) goes into the Carrier Block (7) and raises and lowers it. You must cock the hammer and pull back the bolt to free up the Carrier Block.
For the model 73, you will need to use a screwdriver or lever to lift the lever springs off the lever and Lifter Arm to release the tension on them. If only cleaning, it is best not to loosen the screws because it changes the spring tension.
Raise the Carrier Block enough so you may remove the Lifter Arm from the Carrier and set it to the side. You will want to clean it and later lubricate it. (I use a thin gun grease.) You will also want to clean the frame where the Carrier Block rides.
While you have the gun apart, you may want to polish the Carrier Block using Emory Cloth or a metal polish. You may also polish the surface where the lever rides on the frame and the Lifter Arm.
To lighten the action, you may remove the two lever springs and put a small, thin washer under each lever spring. The right lever spring is very important for proper timing of the Carrier Block. If that spring is too light, the Lifter ARM will not work properly and the action will not cycle properly.
To slightly reduce the trigger pull on the Model 66, you can also remove the trigger spring (19) and place a thin washer under it as well.
To help load the rifle easier, look at the Ladle (127). This is the piece that you push in every time you load a round into the magazine. The back, thinner portion of this piece acts as a flat spring that resists the loading and KEEPS the cartridges in the magazine. You can thin this flat spring to make the gun much easier to load. Of course you do not want to overdo his or the cartridges won't stay in the chamber and the gun will jamb! So I thin it so that I leave the spring at about three/fourths of it's original width. That little bit really helped mine.
Put some Blue (removable) Loc-tite or clear finger nail polish on the Ladle Screw (128) so that it won't come loose. Since the ladle is thin, you must be careful so that you don't strip the threads by over-tightening the ladle screw. That's why I use a REMOVEABLE screw tightener.
Replace the Carrier Block. Then insert the Lifter Arm.
Replace the Right Linkage Assembly. (I lubricate it with thin gun grease) Put the lever back in, then install the lever pin. Be sure that the lever spring is riding on the lever. You may need to put the Lever Screw part way in to hold everything together. Later you can remove the Lever Screw so you can replace the left Side plate.
Replace the right side plate so it will hold the linkage in.
Turn the gun so that the left side is facing you. Install the Left Linkage Assembly. BE SURE the Lever Spring is riding on the Lifter Arm. Slightly tighten the lever spring screw to keep it properly aligned.
Replace the left Side Plate and install the Lever Screw and Side plate screw.
Tighten the screws - for both lever springs, the lever and the side plates.
Put a drop of oil on the bolt and on the hammer where the bolt contacts it.
Cycle the action to see that it all works well.