This FAQ is maintained by Eric Brooks.

Disclaimer – The information provided here concerns guns. Guns are dangerous. Any information provided is for information purposes only. I have tried to ensure that the information is accurate, complete, and safe however there are likely to be errors, omissions, and oversights. Some of this information is just opinion. If you use this information to guide your actions you must do it at your own risk. As always be careful and follow the rules of safe gun handling.

CZ 452 FAQ *

What’s the difference between the different models?

What’s the difference between an 11mm dovetail and 3/8" dovetail?

The standard 22 tip-off dovetail in the US is 3/8" at the bottom and up to 1/2" at the top. The European 11mm dovetail is typically 11mm at the top and perhaps 8mm at the bottom. The 11mm dovetail typically has a 60 degree angle from the bottom inside corner to the top where the 3/8" is typically 45 degrees. The top of the CZ dovetail is flat where many American guns are rounded since the receiver is made out of a metal tube.

Some 3/8" rings will work with the 11mm dovetail. It depends on their design as to how well they work. BKL makes rings that work with either the 11mm or 3/8" dovetail.

First off lets understand what the measurements mean:11mm is 11mm across the top of the dovetail, 3/8" is 3/8" at the bottom of the dovetail. Secondly they are cut at different angles. Near as I can tell most 3/8" dovetails are cut at 45 degrees and the dovetail on my Special is cut around 60 degrees.

I don’t know much about the history of the different dovetails but my guess is that where the measurement was set is important. The 3/8" dovetail is meant to be gripped at the bottom and centered on the bottom. The "claws" need to touch the bottom of the groove to work properly. If you have a solid piece of metal that makes up most of the rings or mount with a little claw on the side the little solid metal must be cut to center the scope over the bore. This is one reason why a 3/8" ring may not be appropriate on an 11mm mount. Not all rings use a 2 piece gripping mechanism – the BKL rings are a good example – they may center themselves by their design.

Beeman 5030M and 5030H

BKL 257 and other models.

Millett CZ BRNO European models

B-Square Adjustable Airgun rings.

CZ. Everyone who has these likes them. They are 0.625 inches high.

Use a dowel to press down on the front of the sight ladder at the point where holes are drilled in the side of the base. Push the sight ladder backwards.

There is no easy way to do this. Some people have ground it off. I have not heard of anyone successfully removing the base although it should be possible.

It depends. Scopes shorter than 12" will fit neatly behind the rear sight base with little problem. You must remove the rear sight to do this. Scopes in the 15 inch range will often fit nicely with the objective bell in front of the rear sight base. In that case you can leave the rear sight in place.

The biggest problems are with bulgy scopes (big 40-50mm objectives and adjustable objectives in particular) and scopes in the 13-14" range. The best example of this is the Bushnell Sportsman 4-12x40AO available at your local Wal-Mart or Kmart. These scopes require a lot of height to clear the rear sight base. I overcame it with Tasco tip-off to Weaver-style adapters and Millett medium rings. This combination puts the scope almost 0.9" above the receiver and clears the rear sight base. This may be uncomfortable for some but is an advantage if you are shooting silhouette or Sporterifle from an offhand position.

The BKL and CZ rings are fairly high and have been used to mount a variety of scopes. I have use the BKL 257s to mount a Simmons 1048 6.5-20x44AO with the objective bell in front of the rear sight base. The Beeman 5030H rings should mount just about anything under 50 mm with their 0.75" height. The Millett High CZ/BRNO rings are in between and should also mount a wide variety of scopes.

I am developing an 11mm to Weaver adapter that will provide about 0.5" above the receiver and will take any of the wide variety of Weaver style rings. With this as a starting point you should be able to find appropriate rings to mount any scope.

If you can find the Tasco tip-off to Weaver-style adapters (about $5) they will work for many Weaver-style rings and seem to fit the dovetail nicely. Beyond that there are some other 11mm to Weaver adapters but they are one-piece and will interfere with the ejection port.

Another option is to have the receiver drilled and tapped for Weaver-style bases. Weaver #61 bases are flat on the bottom and should be well suited to this. If you can bear to have your gun drilled this is probably the best way to go.

I am currently developing an 11mm to Weaver adapter for the CZ 452. That will be available by September. See http://ebrooks77.50megs.com/weavermounts.html

The stock is pressing on the right side of my barrel. Is this good?

No this is not good but just about every Lux and Special comes this way. Some theories are that the router that makes the barrel groove is set up improperly or that this is a built-in pressure pad to enhance accuracy. My recommendation is to sand it down to float the barrel.

A barrel is floated when there is nothing touching the barrel in front of the receiver or the barrel lug. This allows the barrel to move consistently and without restriction as the bullet moves through it. The key here is consistency – you want the bullet to exit the barrel the same way every time. If the barrel is rubbing against the stock it will most likely move differently and end up at a slightly different resting point each time. Floating removes this variable from the mix of factors affecting accuracy.

Most people use a dowel a little smaller than the barrel with some sandpaper wrapped around it to sand out the channel. It is a good idea to make the space around the barrel consistent and at least a business card thickness (You should be able to slide a business card from the front of the stock back to the barrel lug (Special, Lux) or to just in front of the receiver. Be sure to seal the freshly sanded wood with something to reduce the effects of humidity, etc.

A quick and dirty method I have heard of but not tried is to put a washer between the barrel lug and the stock to get an instant free float. I haven’t tried it but it should work as a way to prove the concept.

The bore on the CZ 452’s are a little tighter than other guns and the nice coated rods will not pass through easily. I have KleenBore and Dewey 22 caliber rods and neither goes through easily. One solution is to get a .17 caliber cleaning rod from Dewey or some other manufacturer, get the step up adapter, and use that.

Another option is to use something like the PatchWorm (available from 20-20 Concepts at http://20-20.8m.com/. This is the evolved form of the weed-whacker line cleaning tools many of us have made. Believe me, it is worth buying whether you have a hand-crafted weed whacker version or not.

Another contributor to the problem is the possibility that the rod is hanging up on the extractor. I have cut grooves in all of my rods this way. You should use a bore guide to eliminate some of the play. These are available commercially or you can get an already fired 20 gauge hull, push out the spent primer with a punch or small Phillips screwdriver, and insert this in place of the bolt as a bore guide". For those who do not know, the primer must be fired in the shotgun first; simply removing the powder and shot will not disarm the primer. (Thanks to PigPen for enhancing this passage.)

Another contributor to the problem is the possibility that the rod is hanging up on the extractor. I have cut grooves in all of my rods this way. You should use a bore guide to eliminate some of the play. These are available commercially or you can get a used 20 gauge hull, push out the primer with a punch or small Phillips screwdriver, and insert this in place of the bolt as a bore guide.

PrarieBoy/Brian contributed the following advice:

One of the best sources on the CZ-452 trigger and trigger modifications is this page: Fuzzy Limey’s CZ-452 Trigger Modifications. The techniques described cover most of the basic information you need. There are variations and improvements on many of the methods described. These variations are discussed below.

Adjust the nut behind the trigger. Replace the spring with a lighter spring. Have the trigger to sear engagement surfaces polished. All of the above.

Movement of the trigger before the "break" the point where sear is released and the gun fires. This is distinct from a two-stage trigger where there is a first stage of movement up to a stop after which the gun fires. The stages of take-up and firing are distinct. In a one stage trigger the trigger does not move (except for creep) before it fires. Either type of trigger may exhibit creep. Most people prefer a trigger with little or no creep.

Another way to think of trigger movement is in three phases – pre-travel (take-up), travel, and post-travel (overtravel). Creep happens in the "travel" phase.

Three methods: reduce the trigger / sear engagement area, shim the trigger, sleeve the front trigger pin.

No. With the sleeve method you will need to remove the front trigger pin. Once remove the trigger comes out and you will be able to make the modification without removing the sear pin and having to first chase and then replace the ball and spring.

Overtravel is the movement of the trigger after the release of the sear. Some triggers have little or no room to move after the break. Different people have different preferences however a trigger with little or no over travel is preferred by most people.

There are not many options on the CZ. One method is to put a little epoxy on the top of the sear as described in Fuzzy Limey’s CZ-452 Trigger Modifications. Another method is to install a screw at the back of the trigger as a stop. The disadvantage to this is that the stop must be loosened to engage the bolt release.

Are the scope rings by CZ any good?

Yes, excellent by all accounts.

You can order them directly from CZ, your dealer, or by mail order. J&G Sales is one mail order outlet that carries the accessory clips.

My CZ 452 Special / Lux was shooting fine until I took it apart to replace the trigger spring. Now it doesn’t shoot as well. What gives?

When you reassembled the gun were you careful to reset the action and barrel screws back to their original positions or torque? The guns with the barrel lug are sensitive to the tension on the screw. Try tightening it just to the point where it feels like it is starting to tighten. Shoot a group, tighten slightly (1/16 turn) and repeat until the gun starts shooting tight groups again.

These are all probably covered in another FAQ document but these are here because I could not stop myself. I figured it would be better to leave them.

The answer to that question will depend on what kind of gun you have and what you plan to do with it and how much money you are willing to spend. A 3-9x32mm or 40mm scope will cover a broad variety of situations and is a popular general purpose scope. If your gun is a 22LR you should get a scope that is parallax free at 50 yards rather than the typical 100 or 150 yards of a centerfire scope. Better yet is a scope with an adjustable objective that can focus down to the shortest distance you shoot. Most indoor ranges are only 50 feet or perhaps 25 yards.

Most scope manufacturers have guides to selecting the best scope. A good sporting goods store or gunsmith will help you pick a good scope as well. Another option is to talk with people who do similar types of shooting – they will probably have some excellent recommendations and will often let you try the equipment they use.

Prices of scopes range from $20-2500 with a wide range of quality, features, and durability. Quality optics will hold their value well and have a ready market. It is not uncommon to spend as much or more on the optics than on the gun. If you buy a used quality scope you will be able to sell it without losing a cent.

Parallax errors are created when the reticle and target are not focused in the same optical plane. In other words they are not both in clear focus at the same time. When this condition exists the reticle (crosshairs) will move on the target as you move your eye relative to the scope. The reticle is no longer centered on the point of impact and this can lead to missed shots. These effects are more noticeable in high magnification scopes.

Most hunting scopes are adjusted for parallax at 100 to 150 yards which is fine for big game hunting: the parallax error is small compared to range estimation errors and the size of the target zone on the animal. Many rimfire and shotgun scopes are set parallax-free 50-60 yards. Get a scope that closely matches the range you shoot at. If you have a higher magnification scope and are planning to shoot at ranges other than the parallax-free range of your scope you need a scope with an adjustable objective. If you are shooting targets competitively you need an adjustable objective (AO).

AO stands for Adjustable Objective. Some manufacturers call it PA or Parallax Adjustment. Basically it allows you to get the target and crosshairs in focus at the same time. This eliminates parallax errors and the eyestrain caused by trying to focus the crosshairs and target.

The distance scales on adjustable objective scopes are not always set correctly. The best approach is to recalibrate your scope by finding the point where it is parallax free at a known distance. Some scales can be moved, but some masking tape and a pen work fine although they lack in the appearance department.

Probably not. Most scopes have an eyepiece focus designed to get the reticle in focus. Point the scope at a blank surface, look away at something far off then look in the scope and see if the reticle is immediately in focus. If not adjust the eyepiece focus until it is. Check again by looking away and repeat until it is in focus.

Another common cause of this problem is using a fixed parallax or fixed focus scope on a target that is too close. There is no easy solution to this one short of buying a scope with an adjustable objective.

The optical center is the line that will pass through the center of all the lenses in an optical device. You can be sure that the optical performance of the scope will be best when everything is aligned.

When you mount a scope it will ideally be horizontally aligned with the bore. The best way to test this is to get your scope centered on the optical center, mount the scope, and then boresight to ensure that the scope is aligned with the bore. If it is not aligned you might have one or all of the following problems:

• Running out of adjustment
• Poor optical performance
• Having to adjust windage as you adjust to a different range.

As an example the Simmons 1048 6.5-20xAO has a large indicated range of adjustment - roughly 7 rotations at 9moa per rotation for a total of 63 moa. The actual effective range of adjustment is from 0 to a little over 4 rotations or 40moa. This is on a par with other 1", 20x scopes.

The range of adjustment also varies depending on the position of the reticle relative to optical center. If the reticle is horizontally centered you get the full 40moa. If the scope is mounted incorrectly and you need to apply windage to align the reticle with the bore then your range of adjustment (up and down) will be reduced. The range of adjustment is circular so as you move away from center the distance to the top edge of the circle will be shorter.

Another factor in all scopes is that mounting them parallel to the bore will leave you with less range of adjustment. The 40moa range is 20moa above the optical center and 20moa below the optical center. We will generally never use one side of this range plus a bit of the other side because the bullet is falling away from the line of sight. So with the optical center of the scope parallel to the bore the useful range of adjustment is probably closer to 15moa than the actual range of 40moa. This is a terrible waste.

If we tilt the scope downward a bit so the optical center crosses the path of the bullet then we can dramatically increase the range of adjustment and the maximum range where we can hold on the target. I used Burris Signature rings with their eccentric inserts to raise the back of the scope by 20 thousandths and the front by 5 thousandths. This puts the reticle closer to optical center for most of my shooting between 50 feet and 100 yards plus it extended the useful range of the scope from about 150 yards to about 230 yards with standard velocity ammo.

Other ways to get the tilt are with shims or with a droop adjusted one-piece scope mount (BKL will make one for you - I'm sure there are others). Personally I would take the Burris Signature inserts over shims which will stress the scope if you are not careful.

First you need something like a "V" block to hold the scope. Basically it is two V-shaped notches about 4-5 inches apart that so the scope can rest in it and rotate smoothly. I built one out of 3 pieces of 1x4 with notches in the front and back. I glued some pieces of brass tubing to make a nice "V". The bottom has a 1/4" tee socket countersunk into the top that allows it to be attached to a photo tripod.

Next put the scope in the V-block and find a small target at least 50 yards away or at the parallax setting for your scope. Position the windage knob at the top, note where the horizontal line of the reticle is relative to the target. Rotate the scope so the windage knob is on the bottom and not the position. Adjust the windage knob so the horizontal reticle line is about halfway between the starting and ending position. Repeat until the line is on target in both positions. Now put the elevation knob on top and repeat the procedure with the elevation knob. Go back and check the windage adjustment. Repeat the whole process until the reticle stays on target as you rotate it 360 degrees. The reticle is now centered on the optical center of the scope.

Pull out the bolt, put the gun in a vise or firm rest, look through the barrel and line up on a target, adjust scope so that the crosshairs are centered on the same target you see through the barrel.

If you cannot boresight easily you should shoot first at a target only 10 or 25 yards away. Get the horizontal and vertical adjustments done and you should be pretty close at longer ranges.

Put the gun in a vice or a good rest. Fire one shot. Without moving the gun, turn the adjustment knobs until they are centered on the point where the bullet went. If you did not move the gun and barring scope problems your scope is now sighted in. Go ahead and try a few shots just to make sure. It is usually a lot easier to make the vertical adjustment without moving the gun than the horizontal adjustment: start with that and then do the horizontal.

What causes a gun to be inaccurate?

Variation in shooting technique, ammunition, gun, sight, or any combination of these factors. You must align the sights with the target and hold the gun on target until the bullet has left the gun.

The effect of heat on the barrel.

Variations in pressure on the gun. Locating the rest at different points of the forend. Pressing down or sideways on the gun.

Anticipating and reacting to recoil. Dropping your hand.

Scope problems holding elevation.

Inconsistent hold. Differences in how tightly or loosely you hold the gun, shoulder pressure, weak hand pressure, etc.

Wind from 12 or 6 o’clock (directly in front or behind).

Foreign matter between barrel and stock or insufficient clearance if the barrel is floated.

Wind.

Flinching.

Shifting winds – front or back winds will affect the vertical movement, side winds affect the horizontal, shifting wind will affect both.