[sakopete]

After reading some conflicting information on the subject of 452 and 455 striker springs, we have been in touch with CZ USA. First we ordered a 455 striker spring which we received this morning. It is exactly the same as the 455 striker spring we received from CZ USA shortly after the 455 was introduced in this country. Both are exactly the same as a 452 striker spring. To ensure there was no mistake we called CZ USA. According to Matt at CZ USA there is only one striker spring for the 452, 453 and the 455. They all use the same part number. Our spring differs in two ways from the factory spring. It is made of chrome silicon wire and it is .030" longer.
This is our final statement on this subject.
Pete and Jim Flynn
J&P Custom Products, LLC

 

[NoNewTricks]

That's good info. Always good to hear from the source.

 

[Sporter]

Going by the information above I guess the fellow who posted the picture here at RFC (copied below) last week must have been busy in photo shop (just kidding).... does that lower spring look only .030" shorter? .030" is the thickness of a credit card FWIW.

Is it possible the OP did a typo and meant .300", which is closer to my own measurements on his springs vs CZ stock. Personally, my own recent 455 springs and the ones I've seen in other 455 rifles look like the RFC members posted picture above (bottom one). I get the same coil count and scale wise compared to the others, same length. The active coil pitch (distance from one coil to the next) is .085"...multiply that by the 3 less coils and you got a .255" shorter spring. Take a moment to count the number of active coils between the closed ends ...top spring 29, middle spring 30, bottom spring 26. Springs can shrink a bit over time but they don't exibit dissapearing coils in the process, thats a fact. This along with measured wire size differences (not coil diameter) indicates there are more than 2 things different, we are up to 4 now and 3 of those make a big difference on performance (the spring materials as far as strength goes can overlap within a given range).

Maybe the CZ USA Rep has nothing to do with CZ head plants procurement process for the springs and is talking about the present springs he's looking at in his stock. Manufacturers do change things, as it says on their head website, they are constantly striving to improve on things.

I guess the posting by the O.P. was not meant to be a discussion since people are rarely concerned about any feedback with a "final statement" clause. Since the post was not closed I'm assuming its OK to discuss things among fellow members on the same thread, so I'll throw out a new question that comes to my mind about all this, outside of the above mentioned things...

Why would a spring manufacturer make a striker spring for a bolt action rifle out of ASTM A401 Chrome-Silicone wire instead of ASTM 228 music wire? Judging from the following engineering chart, it likely isnt because CS springs have a lower modulus in torsion rating (11.5 vs 12)...any engineers want to comment? It certainly isn't because CS has a 25% lower upper range for minimum tensile strength (399 vs 300), possible comments?

the only other difference is whats circled in blue....the moderately higher operating temperatures that CS springs are designed to work in. 475 deg F vs 250 deg F. My understanding on this is that CS springs are primarily used in full auto, high cyclic rate weapons which can get up to those temperatures if pushed. (They are also used in automotive valve springs that reach high operating temperatures) I suppose one could calm their worries with a bolt action if you happen to be shooting it in an oven. I've also heard that CS springs in certain conditions can hold up to high impact compressive shock a bit better like in stamping dies...unfortunately they operate in the opposite direction in the bolt, striker springs unload compression suddenly, not gain it. Has anybody ever seen a broken or stress fractured striker spring in a CZ, I searched the data base here and elsewhere and have not heard of that issue ever? Current consensus on this by spring manufacturers is that it is measured in the millions of high stress cycles that automotive engines/manufacturing equipment see in their lifetimes, not on a hand operated breach bolt. Who feels up to the task on commenting on these things, I'm sure there are a couple engineers in here, even some non-PE's who are smart cookies?

 

[timberbeast]

A few things.

First, in the OP, they measure only one CZ spring? Or two, if you count the earlier 455 spring. That one or two springs may not be a good example of all the springs CZ puts in their rifles. 0.030" - how much variance is there in JnP springs' lengths? Surely there is some variation in the production of both CZ and JnP springs? Average length isn't enough to say one population of springs is longer or shorter than another, and a sample of even 10 springs of each manufacture isn't what I would call a "representative" sample.

Second, as I read the ranges on minimum tensile strength, I see they overlap in the reference. That means without testing actual springs, you can't say that CZ and JnP springs are different in this characteristic.

Lastly, in modulus in torsion, or shear modulus, that refers to deformation of the spring from its long axis as it is compressed. So CS steel will bend more quickly and rub the inside of the firing pin shaft. Is that even a concern?

So far, what I'm reading hasn't told me if there is a real difference in CZ or JnP springs. I have bought and used JnP springs and find them excellent. But many of my CZs still have the factory spring as well.

Others see improved performance and better striker imprints on rims, and for them, that's reason enough to prefer the springs that give them better performance.

 

[gmd1950]

A few things.

First, in the OP, they measure only one CZ spring? Or two, if you count the earlier 455 spring. That one or two springs may not be a good example of all the springs CZ puts in their rifles. 0.030" - how much variance is there in JnP springs' lengths? Surely there is some variation in the production of both CZ and JnP springs? Average length isn't enough to say one population of springs is longer or shorter than another, and a sample of even 10 springs of each manufacture isn't what I would call a "representative" sample.

Second, as I read the ranges on minimum tensile strength, I see they overlap in the reference. That means without testing actual springs, you can't say that CZ and JnP springs are different in this characteristic.

Lastly, in modulus in torsion, or shear modulus, that refers to deformation of the spring from its long axis as it is compressed. So CS steel will bend more quickly and rub the inside of the firing pin shaft. Is that even a concern?

So far, what I'm reading hasn't told me if there is a real difference in CZ or JnP springs. I have bought and used JnP springs and find them excellent. But many of my CZs still have the factory spring as well.

Others see improved performance and better striker imprints on rims, and for them, that's reason enough to prefer the springs that give them better performance.

Just locking this one in.

 

[Big-Dummy]

 

[Sporter]

Nice video BD, that sure looks like the biggest .030" difference in length I've ever seen. Oh wel...

A few things.

First, in the OP, they measure only one CZ spring? Or two, if you count the earlier 455 spring. That one or two springs may not be a good example of all the springs CZ puts in their rifles. 0.030"...

I partially agree and also disagree. Dealing with new unused springs coming from a manufacturer I don't find them to fluctuate in lengths to the degree that it would effect their given strength to create an issue with this application. Of course, if they change their own design or tolerancing and issue a new spring, that can account for significant differences. I have not seen any of these changes in the last 5 years, or at least since the 455's have been out, on the CZ springs at least. My manufacturer guarantees +/- 2% on K factor (spring constant) for his springs and there are far more important tolerances to maintain than slight variations (or even .030") on the "free length" in regards to strength and/or spring constant. The working length is a different story, but that doesn't change unless you modify the bolt/striker, or put a spacer in there on the spring. The cut wire is maintained to a +/- .015" length tolerance easily before winding, and the coiling is done on fixed lead screw arrangement or cnc, so that doesn't wander very much either. Heat treating after forming can sometimes cause growth or inconsistancies in strength, but that is why ASTM 228 has a slight advantage in consistancy. Besides, springs are QCed for these things like free length long before they even leave a factory and if there happens to be a bad apple as far as measurable size or performance, it gets tossed.

... - how much variance is there in JnP springs' lengths? Surely there is some variation in the production of both CZ and JnP springs? Average length isn't enough to say one population of springs is longer or shorter than another, and a sample of even 10 springs of each manufacture isn't what I would call a "representative" sample...

People like the others posting pictures and myself have noticed significant differeces in length (not .030"). Pictures and videos don't lie. as I mentioned before there are significantly less number of coils that you can count on those samples...that is not a manufacturing variable, batching, or tolerance issue...it is by design. Machines don't wind 3 or 4 extra coils on a spring, nor do the pre cut wire lengths vary enough to even allow it.

...Second, as I read the ranges on minimum tensile strength, I see they overlap in the reference. That means without testing actual springs, you can't say that CZ and JnP springs are different in this characteristic.

You are repeating what I also noted in my post. But bear in mind two things. It is extremely expensive to reach that upper strength limit with a SC spring as compared to ASTM 228, because it is heat treated (within a short duration of time) after coiling/forming. Personally I don't question the material strength of either CZ or J&Ps springs because they both test out exactly how software predicts for their strength, sizing, design with the input material type....the software uses the same strength of material for CS as ASTM 228 in my case (unless I test the material and input a different variable myself.)

...Lastly, in modulus in torsion, or shear modulus, that refers to deformation of the spring from its long axis as it is compressed. So CS steel will bend more quickly and rub the inside of the firing pin shaft. Is that even a concern?..

This does make a difference, and a big one in regards to ignition consistancy. The much shorter CZ spring has a 9.6:1 length to diameter ratio and the aftermarket spring has a 10.8;1 ratio. Anything over 5:1 becomes more and more unstable according to all spring manufacturers. Now you might think that difference isn't much in numbers, it is....it is not a linear equation, the instability is logarithmic. This is why modern action designers are constantly striving to use shorter springs if at all possible. They can do this in many other ways, material choice/treatment, increasing wire diameter etc.. Action manufacturers recently also prefer to use pin around spring designs as opposed to spring around pins, radiused corners, enlargened pockets etc... Mr. Stillers fine actions for eg. even use melanite coatings to reduce friction issues even more so. Risk of entanglement, bowing, rubbing on interior parts causes inconsistancies in strength and consequently ignition. Other parts of the ignition process are altered to minimize this, its a no brainer to try and use as short spring as possible.

...So far, what I'm reading hasn't told me if there is a real difference in CZ or JnP springs. I have bought and used JnP springs and find them excellent. But many of my CZs still have the factory spring as well...

My main noted difference is in the wire size used, CZ's is thicker gage on all my samples tested over the past few years. Wire gage size is usually toleranced to +/- .00025" because they are drawn through progressive dies, if a wire measures a thousandths of an inch or more larger in diameter, that is by design, not a wide tolerance from my experience. My other noted difference is in actually compressing them to working length and recording the difference. I use a fixture with a digital strain gage to do this. Anyone with a drill press and even a bathroom scale can test a springs strength. Just put the shank of a 4mm drill into the chuck, the scale on the table and use the quill to compress the spring to working height...record the poundage on the scale. Its simple. This is a great way to benchmark your spring since you can pull it out of the gun years later and compare the measurement...tells you if its getting weaker. Sometimes on longer springs they become unstable when compressed so you find a bolt that fits the inside of the spring and put the spring over it. Open the drill chuck enough to clear the bolt and use its jaws to compress the spring down. Always make sure the spring remains relatively perpendicular to the table for an accurate measurement. If you want to get a spring constant measurement, compress the spring about 70% of its full range and set the depth stop on the drill press. Retest at this compression untill you get a repeatable measurement. Put a 1/2" sized something on top of the drill stop and measure again. Record the difference in weight and multiply by two to get the K constant in F in/lbs.

...Others see improved performance and better striker imprints on rims, and for them, that's reason enough to prefer the springs that give them better performance...

Increased performance and deeper strike indent are not mutually inclusive. The CZ 455 is designed to also ignite reliably a 22 magnum round which is thicker brass and larger diameter. If there was an issue with light hits on 22LR, there would be numerous complaints everywhere about the magnums not firing consistantly, or at all...and that is simply not the case.

CZ would not drop the ball on this, especially over a part that costs them literally nothing more to make stronger, if they wanted to. I have used weaker springs to get more performance on the dedicated 22LR 455's like numerous others here have also found, because it reduces the uneccesary vibration that gets sent down the barrel before the bullet leaves the muzzle. Of course, I don't throw away the stock spring, it can easily be switched out if you want to shoot the magnums with it. Bill Calfee and numerous other rimfire gurus make the same claim, you only want enough spring power to get the job reliably done, no more.

I won't argue about if J&P's tests agree with mine on springs, they don't...I just suggest that if someone wants to know for themselves, do a simple test like I mentioned above, its not rocket science. If you have an old spring thats worn and its not doing the job you want as far as ignition, get a stronger one. A far cheaper solution is to stick a 10 cent 6mm washer up in front of the spring and viola...you have another ~1/2 lb of strength on a stock spring. There is room to put quite a few in there if you wish because the stock spring wont go solid (close coils) until its compressed to 1.175". If your spring is fine, leave it alone. If its too strong, I suggest you get a weaker one and try that. Personally, if my rifle can reliably ignite a magnum round, I know that spring is too strong to do it the best way possible on a 22LR round, check the SAAMI data on casing sizes/thickness and it bears this out. I could understand some people not bothering to change springs out according to magnum vs LR, and don't mind a bit of innacuracy because of it. I do so because its easy and takes about 30 seconds to do so.

 

[CarolinaChuck]

Sporter,

Here is my question, and I have had it for a minute. CZ uses the same parts for both .22LR cases and .22 Mag/ .17HMR cases. The footprint of the striker has got to be way out on the rolled edge of the smaller .22LR case. My .17HMR is out past the rolled edge. CZ just overcomes that issue by hammering harder on the smaller sized case for ignition in both rounds; am I reading what you are saying correctly?

Chuck

 

[Sporter]

Sporter,

Here is my question, and I have had it for a minute. CZ uses the same parts for both .22LR cases and .22 Mag/ .17HMR cases. The footprint of the striker has got to be way out on the rolled edge of the smaller .22LR case. My .17HMR is out past the rolled edge. CZ just overcomes that issue by hammering harder on the smaller sized case for ignition in both rounds; am I reading what you are saying correctly?

Chuck

Correct Chuck. The outside of the LR round is .275" and the outside of the 22 magnum rim is .295" (both nominal dimensions). Radius wise, the striker is theoretically hitting about 10 thou too far out. In reality, it is often far more due to some kind of stupid manufacturing snafu they haven't picked up on. Take a look at close look at a bolt nose and the exit hole for the pin tip and you will often see the top part of it is actually outside of the machined recess for the casing, a magnum casing at that. This pic shows it but its easier to see looking directly from above...

They are hitting off the edge on even magnum rounds most of the time. CZ mitigates this a bit by making the pin tip a little longer vertically than is found in most rimfires....they angle and radius less off the top and bottom of the pin tip than they do the sides. One of the first things I do before using a weaker spring is to fix this so that the pin hits closer in on the casing. This is not easy and requires some very careful machining on the top of the striker body to induce a bit of downward angle on the pin. I also open up the bottom of the pins exit hole by about .005" with a tiny carbide endmill. Then I honing an angle bias on the pin tip so that it hits deeper on the lower half than the upper. Even if it still catches a bit of the rims edge, far less of the pins energy is lost trying to crush .043" of solid brass on the rolled over edge. This is an older diagram from years back and I modify it a bit differently now, but it gives the general idea of whats going on.

how it rcoresponds to the casing (ignore order of operations) Rolled edge is about .010"...

This is what primo rimfire strike dent should look like, coming from a top ARA match and winning Class A Benchrest rifles, some are fat and short, some are skinny and long, but they all have one thing in common, they hit inside the rims edge...

 

[djdilliodon]

Correct Chuck. The outside of the LR round is .275" and the outside of the 22 magnum rim is .295" (both nominal dimensions). Radius wise, the striker is theoretically hitting about 10 thou too far out. In reality, it is often far more due to some kind of stupid manufacturing snafu they haven't picked up on. Take a look at close look at a bolt nose and the exit hole for the pin tip and you will often see the top part of it is actually outside of the machined recess for the casing, a magnum casing at that. This pic shows it but its easier to see looking directly from above...

They are hitting off the edge on even magnum rounds most of the time. CZ mitigates this a bit by making the pin tip a little longer vertically than is found in most rimfires....they angle and radius less off the top and bottom of the pin tip than they do the sides. One of the first things I do before using a weaker spring is to fix this so that the pin hits closer in on the casing. This is not easy and requires some very careful machining on the top of the striker body to induce a bit of downward angle on the pin. I also open up the bottom of the pins exit hole by about .005" with a tiny carbide endmill. Then I honing an angle bias on the pin tip so that it hits deeper on the lower half than the upper. Even if it still catches a bit of the rims edge, far less of the pins energy is lost trying to crush .043" of solid brass on the rolled over edge. This is an older diagram from years back and I modify it a bit differently now, but it gives the general idea of whats going on.

how it rcoresponds to the casing (ignore order of operations) Rolled edge is about .010"...

This is what primo rimfire strike dent should look like, coming from a top ARA match and winning Class A Benchrest rifles, some are fat and short, some are skinny and long, but they all have one thing in common, they hit inside the rims edge...

I've reshaped a few strikers on 455's that where 22 LR setups but never done it on a magnum yet. If you reshape it for a 22 LR will it still work on the magnum cases or no?

 

[Sporter]

I only use my magnum on coyotes so I don't have extensive testing of consistancy of ignition and accuracy on targets with the mod...I do get decent ignition on the .17 and the 22 mag if I use the original CZ spring but its probably not ideal for target type shooting. The primer on most ammo now covers the whole base and that rim on 22 mag sticks out about .03" from the casing, You will certainly dent into it even if the top of the pin is nicked off .010" . Hard to find much info on magnum performance in target conditions...around my parts there are no sanctioned matches...maybe in the US its a different story. Kind of has a hunting round status around here and people look at you kind of squirrly if you start yakking about shooting tiny bulls with them.

Going to leave this thread for now since it really is deviating off the OP's topic and maybe revive it on its own thread when I get back from vacation in 2 weeks.

 

[butchi003]

Why so many comments instead to measure and compare the springs strength at working compression of both spring types in question: the J&P and the CZ original.
The test should be conducted on brand new (unused) springs and on springs which were used for at least a year.

Also, I am not sure that the public here knows for sure the material both spring types are made of to comment them. There are numerous Cr/Si spring wire alloys, as well as so called "music/piano" wires. My own experience is that in the past CZ used at least 2 different spring materials for this same application.

 

[Big-Dummy]

The 70 year old GI surplus recoil spring in my Garand works great.

 

[Sporter]

Why so many comments instead to measure and compare the springs strength at working compression of both spring types in question: the J&P and the CZ original.
The test should be conducted on brand new (unused) springs and on springs which were used for at least a year.

Also, I am not sure that the public here knows for sure the material both spring types are made of to comment them. There are numerous Cr/Si spring wire alloys, as well as so called "music/piano" wires. My own experience is that in the past CZ used at least 2 different spring materials for this same application.

Anyone wanting to know the performance of springs can use numerous free software for analysis and all you need is a good dial or digital caliper to measure them and the ability to count coils and input data. Then you take an actual scale and compare the numbers by compressing them to various degrees of compression; you will find them to coincide scarily accurate most of the time. Why? Its far easier for a designer (trying to keep a profit margin and also stay competitive) to choose thicker wire or change another size factor on a spring than to order costly exotic materials or material processes like heat treating, shot peening etc.. This is the way it works in the manufacturing world.

The interesting thing which I find is that when the spring is actually applied in use, numerous individual factors on each firearm comes into play. How true to center axis the striker rides in the bolt, the application of lube, or not, the spring driving off center due to poor footprint/ non perpendicular grinding on its end, coil entanglement, bowing, friction, excess oscillation after the strike, age/wear, torqing over etc... all of these can cause different effects on ignition and accuracy.

Any combination of the above conditions can cause weak or strong hits, excess vibration or any other thing which ruins accuracy. Bill Calfee told a story on his site where he had a competitor he knew who had a killer rifle and for some reason his rifle suddenly started getting inconsistant ignition at one competition. Upon inspection, he found that the striker was very lightly lubed with oil. They cleaned it up and then it was fine again. For somebody to pick up any spring and to make a blanket claim that it would be an improvement over another one in a rifle they never seen or handled...well they should be working as a clairvoaynt is all I can say. For anyone to believe them...well, it goes without saying. The same spring in 2 different rifles could easily create a too hard hit or a too soft one (depending where on the rim the pin hits). If your strikers tip only allows .015" penetration because of how much protrudes out the bolt nose, a truck spring will not give you a deeper dent.

Modern designers of Class A rimfire benchrest rifles painstakenly take great care in making the ignition system by design, one which requires the least amount of spring force to get the job done.