It is possible for one person to perform the guide rod assembly alone but it will be easier with two pairs of hands. Do not worry, you will only ever need to fit the spring to the guide rod once since the guide rod assembly can be handled and cleaned as a complete unit. Items identified in green are named in accordance with the official Beretta CX4 parts diagram.

Guide rod with circlip and collar

There should never really be any need to remove the spring collar (the circular item on the left) from the guide rod. Should you remove the collar please ensure it is replaced with the recessed side of the collar over the circlip since this orientation locks the circlip in place.

Slide the spring from your present plastic guide rod over the steel guide rod and compress it as shown. A wrench as shown may help but the job can easily be done by hand.

Drop the "main spring guide stop" onto the compressed spring as shown.

While the spring is held compressed fit the supplied washer and screw as shown above. Apply a small amount of Loctite to the screw threads before assembly and tighten the screw with the supplied wrench.

The guide rod is now ready for assembly into the "Bolt". Install the guide rod and spring into the bolt in exactly the same manner as the original item. Fit the bolt into the CX4 upper and attach the buffer. The buffer is a tight push fit onto the guide rod. At first sight this may seem to be an insecure attachment but bear in mind that the spring and buffer are under strong compression when the rifle is assembled. There is no possibility of the buffer moving out of position when the rifle is in use.

The supplied buffer is a tight push fit onto the guide rod. Position it as shown.

Move the slide to the forward position with the "Cocking Handle".

Assemble the upper and lower halves of the CX4 in the normal manner. Note that the hammer is cocked for assembly.