Threading barrel gone wrong on CZ457

[Norman1950]

A few months ago I had my 20.5" Varmint barrel threaded. My local range has a full gunsmith machine shop. To start off, they screwed up the length of the thread. It should only be about .400", but it was threaded at .625" (which is correct for 5.56/.223).

I was excited to finally get my Odin Navi suppressor, my first 22LR can. At this range, once the stamp is paid/submitted, a person can use it at the range until NFA approval. With excitement I went to the range and threaded the suppressor on to the CZ457. Put an 8"x10" target at 50 yards and couldn't get it on paper. Thinking the suppressor changed POI, I moved the target to 25 yards. Finally got it on paper and was extremely to the right by at least 6"+ @ 25 yards. It would not group at all. Thinking it was the suppressor, took it off and shot great again, under .5" at 50 yards.

I was concerned about baffle strikes. I was also confused as to why the suppressor made the groupings so horrible. After a few weeks I was able to try the suppressor on my Ruger MKIV, and shot great, and brought the excitement to owning the Odin Navi.

Tonight I was able to do a final test. Brought out my Ruger Precision and put the suppressor on and it shot awesome. Huge relief to know the can was not defective. To check my theory of crooked threads, put it back on the CZ457, and couldn't hit a target at 25 yards.

Now the next step. Do I take the barrel back and have them remove the bad threads and re-thread? Or have the place purchase me a new barrel? My concern is getting another barrel that shoots as good as this one.

 

[AZ Dan]

Did you look inside the suppressor to check for any baffle strikes or lead shavings?

That extreme POI shift is not good...I would bet the bullet is almost certainly striking the baffles at some point. If you can install the suppressor again, put an alignment rod down the muzzle to check for concentricity.

Talk to the gunsmith; if he is any good he will recut the barrel for free to correct his mistake.

 

[candyx]

If the threads are that far off then take it to another smith who knows what he's doing to avoid a second mistake.

 

[Mr. Wolf]

For your consideration:
My CZ457 Pro Varmint had ~.6" thread rather than .4" for 22LR from the factory.

TBAC recommended a spacer to ensure that the barrel shoulder sat flush to the suppressor.

SilencerCo Accessories: Delta Threaded Rifle Spacer 1/2X 28

The Delta Threaded Rifle Spacer takes up approximately .25″ of threads so the rimfire suppressor seats properly.

silencerco.com

The CZ shoots better but it shoots better without the suppressor (with suppressor ~.4-.5" at 50 yds/without ~.3" at 50 yds).
YMMV, happy shooting

 

[Norman1950]

Did you look inside the suppressor to check for any baffle strikes or lead shavings?

That extreme POI shift is not good...I would bet the bullet is almost certainly striking the baffles at some point. If you can install the suppressor again, put an alignment rod down the muzzle to check for concentricity.

Talk to the gunsmith; if he is any good he will recut the barrel for free to correct his mistake.

I checked the baffles and luckily no strikes or shavings that I could see. I wish I could take it home to inspect it closer, but dang ATF!

Taking it back to the gunsmith after the weekend of the 13th, have a NRL22 match and don't want to be without a rifle.

For your consideration:
My CZ457 Pro Varmint had ~.6" thread rather than .4" for 22LR from the factory.

TBAC recommended a spacer to ensure that the barrel shoulder sat flush to the suppressor.

SilencerCo Accessories: Delta Threaded Rifle Spacer 1/2X 28

The Delta Threaded Rifle Spacer takes up approximately .25″ of threads so the rimfire suppressor seats properly.

silencerco.com

The CZ shoots better but it shoots better without the suppressor (with suppressor ~.4-.5" at 50 yds/without ~.3" at 50 yds).
YMMV, happy shooting

Thank you very much for this info. I will check into this spacer if they keep the threads at .600".

 

[Thesepaperwings]

There are some easy tests to do. First take out the baffles and end cap. If it shoot fine with just the tube then add then end cap, if it shoots bad then it's probably touching the end cap. My can shot great on my Savage, 16" cz, 10/22, and ruger pistol. Once I put it on my LRP barrel it wouldn't group and turns out it was touching the end cap because I designed the can with too tight of a pathway. The smith might need your can in hand in order to match the bore line exactly.

 

[Dolomite_Supafly]

A few months ago I had my 20.5" Varmint barrel threaded. My local range has a full gunsmith machine shop. To start off, they screwed up the length of the thread. It should only be about .400", but it was threaded at .625" (which is correct for 5.56/.223).

I was excited to finally get my Odin Navi suppressor, my first 22LR can. At this range, once the stamp is paid/submitted, a person can use it at the range until NFA approval. With excitement I went to the range and threaded the suppressor on to the CZ457. Put an 8"x10" target at 50 yards and couldn't get it on paper. Thinking the suppressor changed POI, I moved the target to 25 yards. Finally got it on paper and was extremely to the right by at least 6"+ @ 25 yards. It would not group at all. Thinking it was the suppressor, took it off and shot great again, under .5" at 50 yards.

I was concerned about baffle strikes. I was also confused as to why the suppressor made the groupings so horrible. After a few weeks I was able to try the suppressor on my Ruger MKIV, and shot great, and brought the excitement to owning the Odin Navi.

Tonight I was able to do a final test. Brought out my Ruger Precision and put the suppressor on and it shot awesome. Huge relief to know the can was not defective. To check my theory of crooked threads, put it back on the CZ457, and couldn't hit a target at 25 yards.

Now the next step. Do I take the barrel back and have them remove the bad threads and re-thread? Or have the place purchase me a new barrel? My concern is getting another barrel that shoots as good as this one.

I would try a spacer first to see if it straighten out the alignment.

If that doesn't fix it ship me the barrel, cover costs both ways and I will thread it. I won't be able to fix the current threads but I can cut it, thread it and put an 11 degree crown on it.

Do you have a link to the thread dimensions you want?

 

[Norman1950]

Just got a call from the shop that did the barrel threading. They told me over the phone that the Odin Works Navi Suppressor did not work with the CZ barrel and they threaded a different suppressor on, and that one shot great. They were trying to tell me that the Odin suppressor was not timed right, but that doesn't make sense to me since it is a "modular" can and shouldn't matter what order or orientation the baffles are.

I have shot that suppressor on my Feddersen 10/22 barrel and shot awesome groups, along with a friend's TCR 10/22 with no problems. I also put it on my Ruger MKIV Lite pistol and had no issues at all.

Does it just come down to the combination of the barrel and suppressor are uncompatible? Or is there something wrong that they are hiding? Just frustrated at the situation, as the whole purpose of the can was for the CZ.

At this time I don't have another can on my end to be able to test it against. My only other thoughts are taking it to another gunsmith and having them check the concentricity of the threads to the bore.

Ok rant over for the moment.

 

[Rimdenter]

It is of up most importance to coaxially indicate the bore or to use a precision bore rod that goes at least 6 " into bore and 6" out to indicate at the very tip of rod while running in a sready rest or a 2 4 jaw system. If the rod is .001 or less and you can is 10" long with .020 clearance your ok. If the rod tip is out .005 your in trouble. Sounds like the shoulder and threads were established with a coaxial alignment problem.

 

[oldfatguy]

Not “timed right” BS. I would not let that smith anywhere near anything I owned.

OFG

 

[AZ Dan]

Agreed....the "not timed right" is complete BS. I watched a review of that can on YT...there is no "timed correctly" for that suppressor.

But, it were baffle strikes, you would be seeing marks left on the baffles from shaving lead, strikes, etc. If the bullet is making the smallest amount of contact on the baffles, you would be seeing visible evidence of it.

My money is on the rifle.

1. (98% likely) The gun smith messed something up with the threading, and doesn't want to admit it. Gunsmiths are an odd breed, and tend to gather on the stubborn+grumpy end of the spectrum. The best gunsmiths just scowl at you until you go away.

As previously pointed out, it is easy for an inexperienced or lazy machinist to incorrectly thread a barrel. There are standards for these kinds of things....as Rimdenter said above, an alignment bore rod .005" out of spec or too short and it's game over.

2. (2% likely) That rifle really does not like that suppressor.
My B14R likes my old Gemtech Outback II more than my newer SilencerCo SS Sparrow. My old CZ 452 liked the Sparrow over the Outback...always a small POI shift on every gun. But nothing like you are describing...6" is absolutely insane.

Maybe you are just unlucky, and that exact suppressor and that exact rifle just don't get along...I could imagine something like the barrel harmonics created a negative induced resonant frequency turbulence in the baffle stack, etc.

N.I.R.F.T - I just made that up and it sounds like real science! Let's use it in a sentence..."Your new suppressor is totally NIRFT'd!"


I think you have tried enough gun/can combos to rule out the suppressor itself being the issue. If your suppressor works perfectly on other hosts, the can by itself isn't your issue.

Luckily, you have a few barrel inches to spare to have it re-cut...preferably by someone else.

If you are in Arizona, I'd be happy to meet up and let you try out my Gemtech and/or SilencerCo, and I could try your can on a variety of other hosts.

 

[Texasflyer]

Are the rounds that hit hitting true or are they keyholing any?

 

[Diver160651]

FYI. It can be virtually impossible to see bullet contact that is intermittent and extremely light by just looking into a baffle stack.

I was using jacket bullets and could not see an issue until I used a cotton swab and a solvent that turned copper color. Once I did that I could see the difference between the general gas/carbon and super faint contact. Cut and had the threads recut and the problem went away.

 

[Norman1950]

Agreed....the "not timed right" is complete BS. I watched a review of that can on YT...there is no "timed correctly" for that suppressor.

But, it were baffle strikes, you would be seeing marks left on the baffles from shaving lead, strikes, etc. If the bullet is making the smallest amount of contact on the baffles, you would be seeing visible evidence of it.

My money is on the rifle.

1. (98% likely) The gun smith messed something up with the threading, and doesn't want to admit it. Gunsmiths are an odd breed, and tend to gather on the stubborn+grumpy end of the spectrum. The best gunsmiths just scowl at you until you go away.

As previously pointed out, it is easy for an inexperienced or lazy machinist to incorrectly thread a barrel. There are standards for these kinds of things....as Rimdenter said above, an alignment bore rod .005" out of spec or too short and it's game over.

2. (2% likely) That rifle really does not like that suppressor.
My B14R likes my old Gemtech Outback II more than my newer SilencerCo SS Sparrow. My old CZ 452 liked the Sparrow over the Outback...always a small POI shift on every gun. But nothing like you are describing...6" is absolutely insane.

Maybe you are just unlucky, and that exact suppressor and that exact rifle just don't get along...I could imagine something like the barrel harmonics created a negative induced resonant frequency turbulence in the baffle stack, etc.

N.I.R.F.T - I just made that up and it sounds like real science! Let's use it in a sentence..."Your new suppressor is totally NIRFT'd!"


I think you have tried enough gun/can combos to rule out the suppressor itself being the issue. If your suppressor works perfectly on other hosts, the can by itself isn't your issue.

Luckily, you have a few barrel inches to spare to have it re-cut...preferably by someone else.

If you are in Arizona, I'd be happy to meet up and let you try out my Gemtech and/or SilencerCo, and I could try your can on a variety of other hosts.

Thank you for your insight. Luckily Odin Works is local to me. The gunsmith is going to have them come look at the gun suppressor combo on Monday. When I stopped in to talk about it they where completely stumped to why it was happening. I have heard many great things about Odin.

As I told them, I am not "blaming" anyone or any product, would just like to know why this is happening.

Thank you all for your insights. Once I hear a good answer I will relay it on.

 

[Norman1950]

Are the rounds that hit hitting true or are they keyholing any?

The rounds are not keyholing, just a very wide pattern an poi shift.

 

[carbonbased]

Thank you for your insight. Luckily Odin Works is local to me. The gunsmith is going to have them come look at the gun suppressor combo on Monday. When I stopped in to talk about it they where completely stumped to why it was happening. I have heard many great things about Odin.

As I told them, I am not "blaming" anyone or any product, would just like to know why this is happening.

Thank you all for your insights. Once I hear a good answer I will relay it on.

What did you find out?

 

[DFOOSKING]

My bergara carbon shoots like 8 mils low and 5 mils right at 50yds with my old AAC aluminum can.

Works like butter with no shift at all on my 77/22.

I put my buddy's much heavier stainless rimfire can on my bergara and there is a small shift but it shot fine.

I wonder if the issue (for both of us) is simply harmonics.

Did you try another can (and inspect its clearance) to see if it shot well. I recall you saying the gunsmith did....but did you?

Plus if the threads were cut long....was your can seated against the shoulder of the barrel or hanging off the threads?

 

[Dolomite_Supafly]

Try removing the stock then place a foam ear plug about and inch back from the front of the stock. Tighten the actions screws back down like normal. Go slow to allow the foam ear plug time to compress if you have a wooden stock. Next, fire a few groups and record the results.

If no change, loosen the stock and move the ear plug an inch farther back. Fire a few more groups. Move the ear plug back. Repeat.

One place should shoot better than the others. Or perhaps it can correct the harmonics that is causing the POI shift.

There is also a rubber slip on harmonic changer that slips over the barrel. Might be easier to use.

This can also help guns without silencers. I’ve used this method to tighten up some decent groups.

My offer still stands to thread it if that turns out to be the issue.