(The procedure is the same for all RUGER® MARK III pistols.)
1. Be certain the pistol is free of cartridges! The safety must be in the "off' (F) position for reassembly.
2. Keep your finger off the trigger. Place the hammer in the horizontal (cocked) position. (The hammer is visible by looking down on the grip frame and is the rectangular object inside the grip frame and near the rear. See Figure 6.)
If you cannot place the hammer in the horizontal position, it is most likely because the hammer strut is trapped behind the crosspin (see Figure 7 - not applicable to 22/45 models). If this occurs, lift the hammer to free the hammer strut from behind the crosspin and then move the hammer into the horizontal position.
If the hammer has been rotated too far forward, it also may be difficult to rotate backwards. Inserting the empty magazine fully into the magazine well will allow the hammer to rotate backwards into a horizontal position. Once the hammer is horizontal, remove the empty magazine.
Before placing the barrel receiver onto the frame, make sure that the loaded chamber indicator pin (Part No. A02611 / Key No. 7 on p. 36) has not fallen out of the receiver.
3. Place the barrel receiver on top of the frame so that the square lug engages the square front recess on the underside of the receiver (see Figure 8A). Push the barrel rearward until it stops, with the rear end of the receiver slightly overhanging the rear end of the grip frame (see Figure 8B). If alignment cannot be achieved by hand pressure, place the pistol (muzzle down) on a padded bench and strike the rear of the grip frame immediately below the receiver with a plastic or wooden mallet. Be careful not to damage the grip frame.
4. Fully insert the empty magazine back into the magazine well. Point the muzzle up in a safe direction and pull the trigger. Gravity should cause the hammer to return to the cocked position if it became dislodged in step 3 (see Figure 9). If not, reach into the rear of the receiver and push the hammer back down flat (into the horizontal position). When the hammer is in this position, remove the empty magazine.
5. NOTE: Before sliding the bolt into the receiver, BE CERTAIN that the firing pin stop (part number A03500, a small pin) is in the bolt. (See Figure 10.) Without this pin, the first time the trigger is pulled on an assembled pistol, the firing pin will fly forward so far as to irreparably dent the rear end of the chamber of the barrel, making the pistol useless. Now, slide the bolt (with the recoil spring upward) fully forward into the receiver. (See Figure 10.)
6. Insert the empty magazine into the magazine well, point the muzzle toward the ground in a safe direction and pull the trigger. The hammer should fall to its full forward position. If it does not, retract the bolt partially and manipulate the hammer through the slot in the rear of the frame until the hammer is in its full forward position. Remove the empty magazine.
Point the muzzle toward the ground. With the pistol in this position, hold the mainspring housing bolt stop pin assembly and press the bolt stop pin through the holes in the receiver and bolt until the tip of the pin protrudes beyond the top of the receiver. (See Figure 11.) You may need to tap the mainspring housing into position with a rubber or wooden mallet. The pin must be fully in place to close the latch in Step 8. Do not yet move the mainspring housing into the frame.
7. Now invert the pistol so that the muzzle is pointed upward. Make sure you can see the hammer strut when you lift the housing up. The hammer strut should go into the oval-shaped cut inside the mainspring housing. (See Figure 12.) Hold the trigger to the rear. While holding the pistol in this position and depressing the trigger, move the mainspring housing into its proper place in the frame. (See Figure 13.)
8. The housing latch can now be snapped shut, completing assembly. (See Figure 14.) Spring pressure should be felt just before the housing is fully shut if the internal parts are correctly aligned.
9. To determine if reassembly was performed correctly, pull the bolt backward and verify that it opens fully. If not, open the latch and repeat steps 6 - 8, above.
10. Replace empty magazine, point pistol in a safe direction and pull the trigger to uncock the gun. Guns should not be stored loaded or cocked. Note that in order for the internal lock to be engaged, the pistol must remain cocked, and the manual safety must be put "on" safe. (See p. 11.)
IF YOU HAVE DIFFICULTY REASSEMBLING THE PISTOL, HERE ARE SOME HELPFUL TIPS!
If the mainspring housing pulls out of the gun when swung in, the barrel/ receiver assembly is not fully rearward on the frame. Repeat step 3, above.
Remember that it is essential that the hammer must be in its vertical, uncocked position as the mainspring housing is swung shut. If the housing is excessively difficult to close, the hammer is probably cocked. Repeat steps 6-9, above.
The foregoing may give the impression that reassembly is difficult, but it is quickly and easily done once properly learned.
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