CZ-452 Rifle Improvements

Over the years, one man . . . Dr. "Nick" Panisuan of Bangkok, Thailand . . . ( I almost showed my age and wrote Siam ! ) . . . has pioneered some simple techniques for minimising these shortcomings.    Unfortunately the public website, on which he long exhibited photos of these modifications, has now disappeared in the ongoing turmoil of the Internet.    Similarly, myself and others have taken his ideas and expanded or improved (?) them to suit our own needs.     This project page will show some of the modifications that any owner of one of these fine guns can carry out with the simplest tools.

Dismantling the barreled action  - Separate it from the stock by removing the bedding screws to be found in the trigger guard.       Take careful note of the arrangement of the various magazine and spacer pieces that are also "uncovered" when you do this.    Some owners find it more convenient to handle the barreled receiver if the magazine fittings are also removed at this time.   Be aware that the number and location of the bedding and trigger guard screws varies somewhat between different models in this series.    The bolt should also be removed by holding the trigger all the way back while uncocking the bolt.

To Lighten the Trigger Pull   -  You will find the trigger / sear sub-assembly held to the lower edge of the receiver by two small pins of approximately 4mm in diameter, (Ref. Figs. 1 and 2 ).   Note the third, centre, pin located in the front trunnion of the trigger itself, is staked in position and should not, repeat not, be removed at any time.     If all you want to do is lighten the trigger pull, then remove only the rear trigger pin using a suitably sized pin-punch, ( a #10 finish nail with the point removed works just fine), and light tack hammer.    This will allow the rear of the assembly to swing down, thus enabling you to remove the trigger coil spring from its' support rod.    ( Note the pull-weight adjustment nut at the lower end of this rod ! ).    In his original version, "Nick" suggested replacing this spring with one half of a #150 stock spring available at that time from most larger Ace hardware stores.    This pattern spring is rarely to be found nowadays, as Ace has changed suppliers
. . .  currently they are stocking springs made by Century Spring Corp. of Los Angeles, CA.  (CSC).

Trigger and Sear Pin Locations

  Instead you have several options, depending upon the desired pull-weight range for your needs.    Some owners have tried modifying the springs from retractable ball-point pens, but they tend to be too light and of inferior materials and workmanship.    If you want a super-sensitive target-style pull-weight of a few ounces, then I would suggest replacing the original spring with the CSC  #C-582 from your Ace store . . .  this is 3/16" dia. x 1-3/8" long x 0.016" wire.    For day-to-day hunting or plinking my recommendations would be for a heavier gauge spring wire.    Unfortunately, the next-heavier, and available, CSC  #C-580 springs  . . . 3/16 dia x 1-3/8" long x 0.028" wire  . . . are a slight interference fit on the locating rod.     Therefore, if this is your preference, you will probably need to either change to one of the 7/32" diameter springs, or try your hand at "slightly untwisting" the #C-580 spring over a suitable nail or other mandrel to expand it in internal diameter  . . .  a tricky operation akin to wrestling a 20 foot anaconda with your finger tips  . . . the spring should slide freely over the rod when finished.

Adjusting Trigger Creep  -  There are several basic methods for doing this.    Regardless of which is used, you will need to remove the front sear attachment pin shown in Figs. 1 and 2 above . . . this separates the sear from the receiver.     It also presents you with a small problem !    In newer models of the CZ-452, the lower front of the sear contains a spring-loaded ball that bears against the receiver . . . the moment the pin is removed this ball tends to disappear forever into 'never-never land' unless restrained, ( Ref. Fig 3 ).    I will discuss this problem further down !    Older versions of the rifle use a captive spring plunger.

Sear Spring / Ball Arrangement

Trigger / Sear Engagement

So how about alternatives ?    If you have the equipment and experience it can be accomplished by removing the "centre staked-in pin" that I just told you never to remove . . .  it is actually the front pin in the trigger trunnion.
Then you will need to machine a slightly larger diameter pin, ream out the old holes in the front trunnion of the trigger, and press in and re-stake the new pin.    Diameter of the new pin ?    Ahah !    This will prove to be a trial and error operation, but the size increase will vary from gun to gun, probably in the range of .010 to .030 ".
Again, much trial and error re-assembly effort to find the right diameter.

Need something simpler ?    Dr "Nick" has come up with a very simple technique for enlarging the pin diameter without all that fuss . . .  I use it myself and it works just fine.    First, get a roll of adhesive-backed aluminium foil furnace tape at the hardware store.    Then separate the sear from the trigger, and clean the surface of that front pin in the trigger trunnion using Acetone or MEK.    Cut a short strip of the aluminium tape.    This strip should be trimmed in width with a sharp knife or scissors to slightly less than the inside length of the pin.    Now carefully wrap and stick the tape strip around that front trigger pin  . . .  three complete wraps works best if the rifle is to be used for competitive target shooting in conjunction with the C-582 spring, and two complete wraps for the hunting rifle conversion.

This wrapping is a little tricky, but if you only "stick down" the tape on the accessible rear, upper and front surfaces of the pin, then carefully feed the loose end of the tape through the gap between the pin and the trigger  . . .  a little push with a screwdriver helps here   . . .  before attempting to pull it tight around the pin, it is not too difficult.    See Fig. 5 for details of a "wrapped" pin.

Tape-wrapped Front Trigger Pin

If you're not confident about the resulting amount of creep that this gives, go ahead and do a trial re-assembly to the receiver  . . .  personally I have found by actual usage that this checking is really not necessary.

Reducing Overtravel  -  With pull-weight and creep now adjusted to our liking, there remains the problem of trigger overtravel after sear release.    Again there are several methods of reducing this.    As the amount of overtravel is controlled in the original design by linear motion of the trigger spring support rod in the matching pocket in the receiver, Dr "Nick" originally suggested light hammering, ( "cold forging" ), of the surfaces of the trigger spring support rod  . . .  this has the effect of reducing it in diameter and slightly increasing its' length.

My preferred methods involve building up the height of the upper surface of the sear in the area where the wrapped trigger pin contacts it.    This can be accomplished by depositing braze spelter, silver solder or soft solder on the upper surface of the sear . . . problem here is heat !    It can destroy the hardness of that heat-treated sear.

Instead try one of these methods.    Thoroughly clean the upper and side surfaces of the sear with Acetone or MEK.    Now add small strips of the aluminium furnace tape to the upper surface to build up the height, and finish up with a strip wrapped over them and down each side of the sear to minimise peeling in use.    An even better method, and the one I now use, is to again fall back on the old reliable 5-Minute Epoxy resin.    Rough up the upper surface of the sear with a fine file or emery cloth and again thoroughly clean with Acetone or MEK.
Mix up a small quantity of the epoxy resin and build up a blob on that upper surface.    After the resin thoroughly hardens, dress down the upper surface of the blob to the desired height with a detail sander tool or fine file.
Like many tasks in the gunsmithing world this is unfortunately a trial and error operation.    If you have reservations about the durability of the resin in long-term use, then cover it with a strip of the aluminium tape from side to side of the sear.

Earlier I mentioned the "disappearing ball" problem.    A suitable replacement ball can be found at Ace in their specialty hardware section  . . .  get some of the 5/32" diameter variety, (the original ball size is 4mm but these are replacements are only 0.001" off ).   The real problem is getting the trigger / sear sub-assembly back in the receiver without again losing the ball and spring.    Try putting a small dab of gap-filling Crazy glue on one end of the spring and fastening the ball to it with light pressure  . . . be careful not to bond your fingers in place during this process !

Then using finish nails smaller than the actual sear and rear trigger pins as temporary holding devices, carefully re-assemble the unit to the receiver.    Now re-insert the sear pin, pushing out the "nail" pin as you do it.
Finally tap in the rear trigger pin, knocking out that temporary "nail pin" in the process.    If, like me, you only have three hands it is tricky but achievable  . . . supporting the barreled action in a padded vise helps at this point  . . . using the "nail" pins as levers also helps to get the real pins aligned with the holes.

One last item   . . . if, like me, you prefer the "American" scope-sights-only version of the CZ-452, either the Sporter or the Varmint variety, I would recommend that you check the fit of the barrel in the forearm of the stock.    Make sure that the barrel is fully-floated back to within an inch or so of the receiver  . . . light sanding of the barrel groove is all that is necessary, although a light coating of MinWax Wipe-on Poly varnish will minimise future moisture absorbtion.    Glass bedding the action will really finish off these modifications, but that's another story !!!

Now go out and play in the yard !

( NB - All photos edited from Dr. Panisuan's originals)

Since the above was written, there have been several "commercial" developments to aid in the above trigger improvements.    First and foremost, Eric Brooks, "Brookie" of Oneonta, NY has put together a kit of assorted springs that can be used to obtain various trigger pull weights to suit the individual owner.    The kit also includes a pair of tubular sleeves of differeing sizes, that can be used to replace the foil tape wrap described in my article for controlling creep. An excellent kit value for $9.00 including shipping . . . saves hunting for them in your local Ace Hardware.    His website contains answers to many CZ-452 questions, and descriptions of other products of interest to the CZ-452 owner.    These include his new low-profile Weaver adapters for both 11mm and 3/8 inch dovetail bases, and "ghost ring" rear sight blades for those with open-sighted variants of this rifle.

So . . . .    visit his Website:                          or E-mail him at :        ebrooks77@hotmail.com

Another item of interest . . . an adjustable sear is now obtainable from Brownells . . . check their latest catalogue.