The Gun Digest Book of Rimfire Rifles Assembly/Disassembly. J.B. Wood
The ZKM-452 was introduced in 1992, and this high-quality rifle was imported from Czechoslovakia by Action Arms. There was also a Deluxe version, which differs only in stock quality and added checkering. A synthetic stock is also offered as a lower-priced option. The present importer of the rifle is CZ-USA.
Disassembly:
1. Remove the magazine. Hold the trigger to the rear, open the bolt, and remove the bolt toward the rear.
2. Remove the front stock mounting bolt.
3. Remove the rear stock mounting bolt, located between the trigger guard and magazine well.
4. Remove the action from the stock.
5. The stock buttplate and the trigger guard unit are retained on the stock by two wood screws.
6. Push out the trigger pin toward either side. Restrain the trigger, as the spring is under tension.
7. Ease the trigger downward. It is not taken off at this time, as it is still retained by its sear-contact cross pin. That cross pin, and the one that pivots and retains the spring guide, are riveted in place, and routine removal is not advisable. The trigger spring and the adjustment lock-washer can be removed from the guide at this point. Take care that the small washer isn’t lost.
8. Restrain the sear, and push out the sear cross pin. Caution: The sear spring is powerful, and there is a small ball bearing between the spring and the receiver. Control it and ease it out. Considering the reassembly difficulty, this system is probably best left in place unless removal is necessary for repair or refinishing.
9. Remove the sear and trigger assembly downward. After removal, the parts are easily separated.
10. The magazine catch and its spring are pivoted and retained by a cross pin. Caution: Control the catch and its spring as the pin is drifted out. The magazine housing is retained on the receiver by two screws, at front and rear.
11. The front sight hood can be sprung outward slightly and slid forward out of its tracks. Backing out the front sight elevation adjustment screw will allow the sight blade to be slid down and forward for removal.
12. The rear sight is retained Mauser-style. Push down at the front and slide it toward the rear for removal. There is no cross pin.
13. To remove the twin extractors, insert a tool and pry the end of the saddle-spring outward, just enough to clear its retaining shelf. As the spring is removed, control it. The extractors are then lifted out of their recesses.
14. With the bolt held securely, use a tool to push the combined striker and firing pin toward the rear, and turn the bolt handle, allowing the striker to move forward to fired position.
15. Grip the front part of the bolt in a padded vise, and use a tool to depress the safety retainer until the safety can be lifted out. Caution: Control the retainer.
16. Easing the spring tension, remove the safety and the retaining plunger.
17. Remove the striker assembly toward the rear. The spring is easily removed from inside the striker.
18. Remove the bolt handle toward the rear.
Reassembly Tips:
1. When replacing the sear and trigger assembly, temporarily install the rear stock-mounting bolt in order to supply a compression surface for the sear ball bearing and spring, as shown. Remember to hook the forward trigger cross pin over the sear. Temporarily insert the bolt body to stop the sear inside the receiver. When the ball and spring are compressed, insert a small drift to hold the sear for insertion of the sear cross pin. This is a difficult operation. Keep a shop cloth or apron around the receiver to arrest the ball if it slips.
2. Be sure the trigger spring adjustment washer is installed in the proper orientation, with the locking dimples downward toward the adjustment nut, as shown. Remember that the upper end of the guide must enter its hole in the receiver before the trigger cross pin is reinserted.
3. When replacing the striker assembly in the bolt, remember that the angled lug goes at the bottom to contact the like surface on the bolt handle, as shown.
4. When the safety and its retaining plunger are installed, it will be necessary to again use a padded vise to hold the front of the bolt. Be sure the plunger is oriented as shown, and that the safety is straight across as it is inserted.
5. Before the bolt can be reinserted in the receiver, the striker must be re-cocked. Hold the front part of the bolt firmly, and turn the handle until the locking