Just get better ammo and don't try and reinvent the wheel. The CZ is a well-made rifle and the limitation is shooter skill and ammo.

 

If its too thick , ie too little head space , it wont close. Worst thing it might not extract so youll have to pop it out with a dowel or cleaning rod.
Theres no lugs on that bolt , its locked down by the handle, if its starting to show wear there , youve got it too tight.

this: is the best idea

 

while you're messing around with the rifle, keep in mind that Eley brands have thinner rims than Lapua brands and SKs and CCI. ForWhatItsWorth.

If you tighten up your headspace "too much", you might just cause your bolt to close harder. You'll see that first with Lapua/SK/CCI

It's been proven again and again that headspace isn't a big deal. About the only thing it'll do for sure is on some rifles, opening up the headspace can weaken the firing pin hit.

 

Your CZ will shoot CCI Standard Velocity well enough at 50 yards. That's two boxes for $10!

 

My first shots with this rifle were with CCI SV and Eley Target. Maybe the barrel wasn't seasoned enough but the CCI SV gave me a flyer in every group while the Eley Target shot much better, even yielding sub MOA groups about 1/3 of the time. I've shot alot of high power competition in the past but this precision rimfire game is pretty new to me. I'll give the CCI SV another chance and take my time making sure the barrel is fouled. I appreciate all the help!

 

Try a Waltz die if you want more consistency in low end ammo.

 

Hooray, the truth will out.
Fritz

 

For every stray, there's a cause.
Sometimes it's an abberant breeze, sometimes shooter movement,
other times it's due to a cartridge problem.
It can be caused by a hefty velocity difference,
an out of balance or damaged bullet wobble that dumps it off line.
A poorly assembled cartridge won't produce the same trajectory as the rest.
Cheap ammo is cheap for a reason. Use cheap stuff when results are unimportant.
Or, get really close to what you aim at, so the cartridge problems have minimal effect.
Works for me.

 

As long as the headspace is within a safe range it's not worth messing with despite what some might think or say. The latest craze is adding shims to the bolt to tighten it up. I actually thought about doing this to my old Remington 513T years ago but never did. The rifle shoots really well despite the headspace being a bit on the sloppy side. Then, a few years later I read a couple of Calfee articles about rimfire bolt-action headspace and the pitfalls of shimming a bolt to tighten it up. What he said in those articles made a lot of sense and I wish more people would read them. You can buy the Art of Rimfire Accuracy ebook for $10. It's a worthwhile read even if some of the info is dated by today's RFBR standards

As others have mentioned, as long as your rifle, equipment, and conditions are capable of good accuracy, the way to achieve consistently better accuracy is to buy good ammo. There's no other way around it. Sure, occaisionally you'll get a batch of cheaper ammo that shoots well. I have some Norma TAC 22 right now that shoots above it's price range if you overlook a flyer here and there. Even so, it doesn't shoot nearly as well as the high-end ammo I have

 

As others have mentioned, as long as your rifle, equipment, and conditions are capable of good accuracy, the way to achieve consistently better accuracy is to buy good ammo. There's no other way around it. Sure, occaisionally you'll get a batch of cheaper ammo that shoots well. I have some Norma TAC 22 right now that shoots above it's price range if you overlook a flyer here and there. Even so, it doesn't shoot nearly as well as the high-end ammo I have

This is starting to make more sense to me. When I shot high power rifle competitively, I always considered it as much a reloading contest as a shooting contest. I did pretty good in high power because I turned out some very accurate ammo (and I had outstanding eyesight at the time). With rimfire ammo, the only apparent way to control quality is to buy it. Unfortunately, there seems to be a shortage of the better quality ammo on the maket now. I will say that, so far, I am a bit disappointed in my CZ but I'm going to keep working at it. So far, I've only put around 300 rounds through the gun. I did try more of the CCI SV today (wife is on a trip so I got a pass for Mother's Day). The best group out of 10 - 5 shot groups came in at .600". The Eley Target was more consistent but still had nothing under .500".

 

3 legs of the accuracy tripod, right Bob?
Skill, equipment, ammunition.
All 3 legs have to function correctly to obtain consistent accuracy.
It would be difficult to be competitive with off the shelf centerfire cartridges.
With rimfire, we're subject to the whimsy of the cartridge assembly line lottery.
Can't build our own, so finding well made cartridges is a never ending job.

 

my results using a dial caliper mirror the results seen in older posts on this forum - .0385" to .039" from those who used rim thickness gauges. I also saw a post which listed the spec for 22 LR headspace as ".0425" Go, .045" No Go".

SAAMI specs for .22 S/L/LR:
Headspace = 0.043" to 0.051"
Rim Thickness = 0.036" to 0.043"

Ammo I've measured was 0.037" to 0.044" rim thickness.
I've only had one bolt that was over spec at 0.061" headspace, and it had continual problems with light strikes. I adjusted that bolt down to 0.045", and it's been great ever since.

I agree with the others that reducing head space won't do much for improving accuracy. It mainly improves reliability. It's similar to chasing your tail sorting ammo by weight, rim thickness, or other measurements. Get the best ammo you can find and afford, and practice a lot.

One other thing is about wind. Looking at the effect in this RH twist chart:

You will have the biggest problems shooting with a wind coming from about 12:30 and 6:30. Just a slight wind direction variation will shift bullet impact between 12/1 and 6/7 in the chart.

 

I'm going to post something that goes against all the conventional wisdom but I don't care.

Everybody that wants to improve their precision, wants their headspace reduced to .043 . But its one of those things that No One has ever proved it does anything in a rimfire. I'm nort sure it does much in centerfire either. Yes we all do it and I did as well but. Bill Calfee who builds some of the finest 22lr benchrest rifles did an experiment where he increased headspace on a 52D to a point where he had misfires and never saw a loss in precision. In my ignorant days I fooled around with measuring rim thickness with an $80.00 Bald Eagle rim thickness gauge. I had a lot of Eley Match and a lot of Lapua Midas I used in competition and won with both. The average rim thickness in the Eley was .031 and the Lapua was .0356. Whether you believe the numbers or not, there is still .004 difference between them no matter what the actual reading is. The rifle used in competition is a custom Anschutz that never had anything done to the bolt to reduce head space. As always, my opinion is; test, test, test and find the lot of the particular brand/type you want to shoot. If you can't find a lot that suits you, you are going to have to move up a notch and spend a little more money.

 

Performance costs money, you can pay up front or you can pay later with work and more money. If you end up with what you paid for how can you be unhappy.

 

You've mentioned you used to shoot competition in HP so this may be irrelevant, but you haven't mentioned any of your 'accessory equipment' like scope, rest, trigger ... Maybe all is great but may still need 'tuning' too. a scope with Adjustable-parallax, 20X or better, good quality benchrest or bipod or bags etc. And a light trigger, ca 2# or less, to avoid affecting shots. Glasses Rx 'up to date' ? And as mentioned, 'buy accuracy' in ammo.
Hope this isn't 'too basic' to consider.

 

Good ideas. When I shot HP competition, it was in the service rifle class with a sling as the only support and iron sights (which has since changed to allow low power scopes). Since I'm shooting a light weight sporter, I was thinking a bipod may help reduce cant. I did buy a new bag recently which has helped my steadiness some but the groups only improved slightly. When I bought the scope, I planned to hunt squirrel with the rifle so I wanted something that went down to 3X or maybe 4X max. I bought an Athlon Talos 3-12 X 40 with the parallax adjustment but I got a duplex reticle. I can see now, that for bench shooting to improve groups a finer reticle with a small dot center would probably have been better. In spite of the scope, three of the first seven 5 shot groups I shot with that CZ were sub MOA. On my next range session, I plan to work on testing stock bolt torque to see if I can shrink the groups a bit more. While challenging, this is also fun and I may find myself going down the road of more rimfire rifles, more scopes, etc... ( just when my wife thought I was selling my safe-queen skeet guns never to be replaced).

 

PS - I didn't address the 'original question', but I don't "Believe" in either as a serious consideration unless you're dealing with $$$ high-dollar rifles. And I don't consider my CZ 457 V-MTR as 'High-dollar', even with ca $1K 'accessories''.

 

jb - That's very nice shooting, esp the Mauser, ca 1"-ish with sights. I can't do that with a scope on my 722.
However, I was replying to the OP. In post #10 he mentioned he had shot HP. He hadn't described any of his equipment, and it's sorta relevant to his issue.

 

I had to try and measure the headspace in my CZ 457 American but was unable to get an accurate reading using my dial caliper, using a method suggested by a YouTuber. While I had the gun apart, I did want to lighten the trigger a second time so I did that. Taking some of the suggestions given in this thread to heart, I went to the range today and tried to focus more on my skills and to do a test of various action bolt torque values. Not the best day as we had 10-18 MPH winds but my club's range in down in a hollow so I thought it might work. Still had some varying wind from R to L, but I was encouraged by the results. Tried the bolts torqued to 15#, 17#, 20#, 22# and 25# (inch pounds). Only shot two, five shot groups at each value and I did get some horizontal stringing, which I think can be partly attributed to the wind. When the wind died, my groups got much better. I plan to repeat this on a calm day but my best groups came at 20 to 25 inch pounds of torque. Three of the six groups between 20 and 25 inch pounds of bolt torque were sub MOA with the best two measuring .294" and .309". Two of the remaining groups which were not sub MOA showed horizontal stringing. I agree with what you guys have told me - that I need to leave my headspace alone and work on finding the best ammo and honing my skills. These groups today were all shot with Eley Target.

 

I tried measuring the rims, weighting the bullets, etc. with no appreciable results. I’ve gone through a least 15 brands of ammunition. I’ve adjusted the torque screws. I have not consulted with a psychiatrist, nor yet, but you can’t shoot with any consistency using the wrong ammo. The goal is to shoot tight groups with the cheapest ammo your gun likes. It’s hard to do. I mainly try to shoot moa at 100 yds. Most of my 5 shot groups ( not all), will be there . Using SK Long Range, I can do it. I’ve shot over 300 rounds with CCi at 100 yards with no luck. 50 yards, yes , 100 yards no. I can shoot less than 1.20 with several brands, but when you want a tighter group, it’s going to cost you unless you’re lucky. I really enjoy these discussions.

 

It's raining. Again. Typical for Florida hurricane season.

Time to pontificate on the ammo y'er rifle "likes".

Question: How do you obtain repeatable accuracy?

By eliminating those problems that cause trajectory spread.

Start with the shooter, learn the basic skills.
Position, stability, focus, follow through, body mechanics and reading wind effects.

Then there's the equipment. Supporting gear like bags,
rests, bipods, benches, jackets and the mechanical aspects of the rifle.
Is everything as good as it can be? Is fit and finish
capable of doing everything exactly the same with each pull of the trigger.
No random movements, no shifts in alignment while the projectile is in the barrel.
Has the barrel been machined and finished so as to allow
each cartridge chambered to be aligned in the same position for every shot?
Is the bore and rifling smooth enough to prevent damage to the bullets surface
so as to maintain the symmetry and balance of the projectile
as it travels and exits the barrel.
Has the crown been machined to provide even pressure release as the bullets exit?

Then there's the ammunition...has it been manufactured and assembled
to provide the degree of uniformity necessary to produce predictable trajectories?
Any variations in assembly, finish, dimensions, chemistry
will cause changes in velocity and how the bullet interacts with the atmosphere
during it's flight downrange to the target.

What a rifle "likes" are uniformly well made cartridges with tight muzzle velocities.

Thinking you just have to find which brand will make a rifle happy,
is an internet fable foisted off on the gullible who are still learning.

Garbage in = garbage out.

In order to produce consistent accuracy, it all has to be done right.
No rifle can fix poorly made cartridges.
No cartridge can fix a poorly made rifle.
Shooter, setup, rifle and ammunition all have to do their parts.

 

I hope this helps.

 

Ok, let me tell you. I started from scatch, I knew beans about the 22lr. I never had any interest in them until I heard there were guys shooting 2-3 hundred yards with them. A reliable friend dealt with a guy that killed a cormorant 250 yds away with 3 shots. I did not know the imperative relationship between your gun and ammunition. I read like you have. Every thing I say to you only applies to my drive to shoot 1 inch or less at 100 yards. This is on me, not more practical 50 yard guys. First mistake, I bought a $ 1300 Volquartsen semi automatic. It’s my worse 100 yard gun. Beautiful, smooth, Ruger 10-22 clone. Fun to shoot, but for me, I would not buy it again. I next bought a Christensen ranger. It’s pretty good at 100 yards with SK Long Range. However, on a whim I bought a savage fv- sr for $ 250. It will out shoot my two other guns with a variety of ammo, mainly with SK Long Range at 100 yards. I replaced it with a pro-varmint stock. I wish someone would have told me what I told you. I don’t want to mislead you, but this is what I experienced.

 

One thing I learned in my 10 year journey to shoot small groups with 22s without spending a fortune . . . You have to spend money on ammo. Two ways, buy top shelf stuff and ammo test, or buy the lower end high grade and shoot a heck of a lot more of it ammo testing yourself into a good lot. Eley Target is exactly the right ammo to use on the second approach - it can have some outstanding lots.

A second thing is to change your approach to scopes. I've never particularly liked or could afford high end high power scopes, I've always found that you can get much better glass spending you $$$ at lower powers. So I have several scopes in the 10x to 16x class with AO and nice glass - Sightron S111s etc. How do you shoot very small groups with 10x? Change the sighting paradigm. Instead of using a high power scope to find the centre of a black bull, make your own target centre's and shoot at a white centre. This is the same principle as a double aperture sight, it allows your eyes most powerful qualities to centre the reticle within the white space. These 100M groups shot at 12X

Shoot in the best light. Find the time of day when your eyes are at their best.

Cheers

 

One thing I learned in my 10 year journey to shoot small groups with 22s without spending a fortune . . . You have to spend money on ammo. Two ways, buy top shelf stuff and ammo test, or buy the lower end high grade and shoot a heck of a lot more of it ammo testing yourself into a good lot. Eley Target is exactly the right ammo to use on the second approach - it can have some outstanding lots.

A second thing is to change your approach to scopes. I've never particularly liked or could afford high end high power scopes, I've always found that you can get much better glass spending you $$$ at lower powers. So I have several scopes in the 10x to 16x class with AO and nice glass - Sightron S111s etc. How do you shoot very small groups with 10x? Change the sighting paradigm. Instead of using a high power scope to find the centre of a black bull, make your own target centre's and shoot at a white centre. This is the same principle as a double aperture sight, it allows your eyes most powerful qualities to centre the reticle within the white space. These 100M groups shot at 12X

View attachment 400100

Shoot in the best light. Find the time of day when your eyes are at their best.

Cheers

Good information. Most people think 100 yd. groups is impossible. It can be done with the right gun and ammunition. I can’t shoot every 5 shot group within 1 inch, but I can do it a heck of alot of times. If you can group at 100 yds., you can group at 25-50 yds, but not the reverse. My 50 yd. CCi groups are terrible at 100 yds. Welcome to the Century club. I am looking for more members.

 

Get a hornady rf rim thickness gauge. I got mine from midway for $35-7 if i remember correctly. Even sorting cci sv $4.25 a box of 50, for same rim thickness helps to eliminate flyers and verticle. Not perfect, but it helps.

 

Now I did not read all posts, but with the .22lr, rim thickness IS headspace. You can weigh ammo all you want, but you are wasting your time. Too many variables. You have the weight of the case which may be different from case to case. Then the powder charge, then the weight of the bullet, and let’s not forget the priming compound. So weighing loaded rounds is a total waste of time. The only thing that matters is rim thickness consistency.

 

Gizzy, You're generally right, tho some rifles will draw the bolt "tighter" than others. It depends on where the bolt handle locks up, it might be more loose on some and tight on others. The variation results in a few thou difference in the "Jump" of the bullet, which may have an effect on accuracy in some rifles. A lot depends on the actual chamber length - there are differences by manufacturer and gun to gun.

 

Rim thickness?

Which part of the rim?

The part where the pin hits?

How can you be sure which part of the rim is the portion being measured?

I can see/measure differences in rim shape/thickness, on the same cartridge.

 

Cheap rim thickness gauge. I just use a fired 22 hornet casing and drop a 22lr cartridge in and measure the rim thickness. Probably any .223 casing would work just as well.

 

I tried measuring rim thickness a few times.

I found problems with the technique.

1) Which portion of the rim do you measure?
It's not the same all the way around the cartridge.
It varied several thousandths.

2) When I tried the rim sorted cartridges,
the chronograph showed the same problems as the unsorted cartridges.
Hot and weak cartridges still showed up, which meant the rim measurements
had little to no effect on the velocity spread.

3) Sorting by rim thickness won't fix poorly made cartridges.
It doesn't fix powder/primer variations, sloppy assembly, rough handling
differences in components or other cartridge dimensional differences.

4) Test sample size will cause incorrect conclusions.
Basing y'er opinion on a single box of cartridges will allow an incorrect conclusion.
Test a full brick, at least 500 cartridges and watch the results vary.

 

I tried measuring rim thickness a few times.

I found problems with the technique.

1) Which portion of the rim do you measure?
It's not the same all the way around the cartridge.
It varied several thousandths.

I have two rim sorting setups. One that works with a dial indicator and one that fits on a dial caliper. Both showed variations in rim thickness. The dial indicator version measured at more precise points. So that showed more variation than the caliper setup. The caliper measured across the whole rim and was more general but you could still rotate the round in the holder and I'd get a different reading. The variance in rim thickess for one round and the fact that never saw any positive results from sorting led me to finally give it up

 

Head space is the distance from the bolt face to the datum of the farthest point a cartridge can go in the chamber. This point can be controlled by the cartridge rim, shoulder or a “belt” and has a plus/minus tolerance in both chamber and cartridge dimensions - usually, not always of about 0.010” total overall for all sporting chambers and munitions. The snugger the cartridge rests between the bolt and chamber can result in more uniform ignition and helps reduce run out keeping the cartridge centered in the chamber resulting in the bullet entering the leade straight on. These both have an effect on accuracy in some measure. The belief is the snugger the better to some degree, a crush fit isn’t what you want however.
Reloaders strive to keep control of the cartridge dimensions, along with bullet “jump” to the leade, powder type and charge consistency. Rimfire shooter have no real control over these other then to rely on the manufactures QC.
Variation in rim thickness doesn’t really matter as long as the high spot is the same across the sample as this is the determining factor in how deep in the chamber the round will go. A bolt to chamber gap can vary by the allowed tolerance as long as the cartridge you pick has a rim thickness that matches it accuracy shouldnt be compromised