How Good Are CZ Barrels? An Experiment (Pic Heavy)

Leuchtkafer

Leuchtkafer

Member
Rating - 100%
2   0   0
I have a lot of content to put up, I'll have to break it up into multiple posts. I'd appreciate a hold on any commentary until I've completed my uploads, which will be target results. Thanks in advance.

CZ, a nice rifle for the money, but is known to be luck of the draw on how well any particular example performs. Why might that be? They give their barrels some sort of lapping process and cold hammer forge, they should be pretty decent barrels then, no? It appears that they drop the ball on the finish machining, numerous complaints can be found about crowns looking like they've been "cut with a dull butter knife" to burrs hanging off the rifling in the chamber. It got me thinking... How good would a CZ barrel be if it was finish machined properly? To answer this question I've had my nose to the grindstone, working away behind the scenes. Much of what I've been doing is content for another forum entirely, though it was necessary to get to this point and took me many months to work through.

On to the project. The barrel selected is a 24" threaded barrel from a 457 American. I found that the CZ bore is very tight, so much so that none of the reamer pilot bushings would fit it, the smallest in my set being 0.215". First task was to custom fit a bushing to the bore which ended up being 0.2122". Well actually the first thing I did was cut off the entire factory barrel tenon, as can be seen.





With that done, I setup a lapping/slugging jig. A length of delrin precision drilled and reamed for my cleaning rod to guide it without any slop. I slugged the barrel to evaluate what I was working with, and it felt really nice right up until the last few inches. I describe it sort of like a "hiccup" in the bore, felt like it was going to tighten up but then it loosened off before tightening back up to exit the muzzle.



That just won't do for this project, so I went ahead and lapped the barrel to see if that "hiccup" could be eliminated. I cast a lap and worked it until it felt worn, cleaned the barrel and slugged again to evaluate. Some improvement but still able to detect the "hiccup". I cast a second slug and lapped. After this, the slugging feels very good and I cannot detect the "hiccup" anymore.



Next I cut the new tenon for the barrel. There's a fair bit of slop in the fit between the factory barrels and actions, I did mine with minimal slop while still being easy to install and remove from the receiver.



Once the test fit was good I could proceed.

 
The next step was to setup for reaming the chamber. Since bores are usually not concentric with the exterior of the barrel, it is necessary to use a precision indicator rod inserted in the bore. Runout close to the chuck is adjusted by the 4-jaw chuck, runout at the far end of the rod is actually adjusted by the spindle spider (not shown). Back and forth we go until it's running perfectly at both ends.





Now the fun starts, in we go with the reamer!



I reamed until I hit a point where the bullet would be driven into the rifling 0.070". Why this amount, you ask? Well, honestly it was just an educated guess to give me a decent amount of bullet engraving while still being able to extract a live round. I would not learn if I was correct until actually testing the finished product.



 
So how'd I do? Let's take a look at the factory chamber as seen through a borescope



Now we shall observe the chamber I cut



It's like night and day. You can see those accuracy robbing burrs I mentioned earlier in the factory chamber, while mine is nice and clean. Hey CZ, was that so hard? :p I also re-crowned the muzzle while I had the lathe setup for running a barrel. With all the lathe work complete, next I setup to mill the remaining features on the tenon, first cutting the relief for the bolt guide lip to set a reference point to orient the other features.



Relief cuts for the grub screws





Extractor slots



Fresh off the machine, all done! Yes, yes, I still had to de-burr, it was just such a relief to make that last cut on a complex project without anything going wrong that I got ahead of myself.







Test fit into the receiver with all the bits and goodies installed, function check passed, we're almost range ready! ;):cool:
 
I strongly advocate for the use of a muzzle device to get the best out of a barrel, so it would be silly for me to shoot this without one. I then spun up an adapter to fit one of my Harrell's onto this barrel. It's a good snug fit that doesn't just slip on freely, you have to push it on with a little force, so the clamp screws on the Harrell's don't need to be cranked down to grip solidly.







Before we get into the meat and potatoes, I shot a couple baseline targets with the barrel as it was from the factory. Meets CZ's 1" at 50 yards standard, but leaves much to be desired.



 
For the first range day I had the Harrell's on without any weight additions to it. I used RWS Target Rifle as the test ammo, though some say it's not good enough to use for tuner testing, I think you can see what you need to with some decent but less expensive ammo. I'm not saying I'm right or have it all figured out, I'm just saying here's what I did, here's the results, and here's what I think about them. I test at 50 yards since that's what I'm most familiar with. I started at the lowest setting and shot 5-round groups at full revolution (25 clicks) intervals. This is to give me a rough idea of what the muzzle device is doing to the barrel over the full range of settings. I don't just look at the groupings, that's an incomplete picture. I'm also observing any changes of the POI as I go through the settings range.



Hmm, frankly I didn't like what I was seeing. A lot of POI shift, wild groupings, and just overall inconsistency. I repeated setting 2-75 and bracketed it + and - 10 clicks. OK 2-65 looks alright for two groups in a row. I then explored around certain settings in finer detail, and found just a click or two could throw the groups out from what was a promising setting. I do not like to see that kind of sensitivity. Given this barrel is 0.709" at the muzzle (well at the shoulder before it's threaded), it's a pretty light barrel and I suspected a standard Harrell's would be too light for it.



I had enough time left to pick the best setting and see what would happen with some better ammo. First two groups shot at 2-65, hmm vertical, I dropped it to 2-64 for the other three groups, ahh, better! I still don't like that one click setting sensitivity.





So after day 1 and shooting those last two targets, I came away seeing potential. Needs a little more work, probably more weight on the Harrell's which I would do for the second range day. It's better than it was before, there's that, but I think it's got more to offer still.
 
For the second test day, which was this weekend, I added the lightest weight from the Harrell's set, which adds 2.89oz. You can tell right away, this is moving in the correct direction, much more consistent over the settings range. I tested in the same manner as the first time.





Again I picked what I thought would be the best setting and did full targets with better ammo using it.



This was going well until the very last shot, as I closed the bolt I heard "zzziiippp!" like I had just twisted the scope knob.... you've gotta be kidding me! :oops: Sure enough, out of the group and no 1/2" challenge for me :rolleyes:

Hmm, OK I'll shoot the other half of the box, why not? I started on the bottom left bull and it was either shot 2 or 3 and that flier showed up. AHHH! Right off the bat... I finished the target anyway and glad I did, because oh boy, other than that one odd flier this is looking great!



I didn't have enough Eley Team for a full target so I just shot 10 foulers with it and used Match for this last target. Hey! A 1/2" challenge target! Woohoo! :D



Alright, so I still think the Harrell's needs more weight, the next heavier one is 4.65oz and that just might be the ticket. Second range day take away is oh yeah, there's real potential with this barrel, I just have to get it dialed in jusssst right. Oh, live round extraction was successful so the chamber depth I cut was good. I don't know where the line is where extraction could become an issue. So, there we go. I'd say CZ makes a pretty good barrel. If it slugs well and is machined right, it should be a good performer.
 
The barrel looks very good now, at least in the chamber area.

It's too bad CZ doesn't spend a little more time and effort on their barrels, but as we've said in the past, from a business point of view they don't need to.

As long as they can sell everything they produce they don't care how good their rifles are, or how much potential gets left on the table.

I sold my last CZ a couple years ago, and really don't see another one in my future, except maybe as a plinker. They haven't changed the way they do business, and they're not likely to.
 
Leuchtkafer said:
Hey! A 1/2" challenge target! Woohoo!
Click to expand...
Nicely done. After all the work put into the 457 American barrel -- including lapping the bore, remaking the tenon and cuts, reaming a new chamber, adapting a tuner collar, and shooting to find a good tuner setting -- it must feel satisfying to shoot a target that meets the 1/2" challenge.

As you no doubt know, there are over 30 CZ's bolt action rimfires -- 452's, 453's, 455's, 457's -- of various models on the 1/2" challenge list, all with factory barrels and most likely without tuners (in addition to some with custom barrels with and without muzzle devices).

While it's possible that some models are for one reason or another better shooters than others, do you think that different ammo could have given the 1/2" challenge level of success without any modifications or the use of a tuner?
 
Great experiment. Big thanks for sharing this with the public!

I was surprised to see the original chamber to be so rough in your rifle.
I have two cz457, both are MTR version with match chamber. neither has anything like I see on your pictures. See the borescope pictures from one of my rifles:

WIN_20240925_18_48_28_Pro.jpg

WIN_20240925_18_48_11_Pro.jpg

WIN_20240925_18_48_01_Pro.jpg

Both my cz457 MTR are on the 1/2" group list with successful submissions.

though MTR is considered to be on the higher end of the 457 spectrum

Here is one of the recent shoots with a cheaper Norma Tac-22 ammo at 50yd
 
Last edited:
thanks for taking the time to share your experiment
Leuchtkafer said:
The barrel selected is a 24" threaded barrel from a 457 American. I found that the CZ bore is very tight, so much so that none of the reamer pilot bushings would fit it, the smallest in my set being 0.215". First task was to custom fit a bushing to the bore which ended up being 0.2122".
Click to expand...
QC of the base barrels looks to be to a lower standard maybe? Tough to guess from a single example, would hope a 'match' chamber/barrel would be better
CZ bores are known to be smaller than others
 
Thanks for an excellent write-up.

You have effectively made a custom barrel, however, so comparing it to a mass produced one is neither here nor there.
 
This is a very interseting thread. Many might not realize this is from what I think a former CGNer under the name RabbidMu45 whatever. The first CGNer to complete the !/4" challenge and an extremely knowledgeable member and shooter. Ongoing conflicts between him and another well known member arent a secret. Glenn and Firefly need to realize they both have a wealth of information for the new too shooting community and take a breath when opinions dont align. If theres a conflict just send me a message as Im always correct!! Ill staighten both of you out. NOW THAYS FUNNY. Hows the brewin goin
 
You must log in or register to reply here.
Back
Top Bottom