I bought a new CZ550 9.3x62 with a factory threaded barrel

It sat in the gun safe for couple years waiting for a suppressor

I got the suppressor, took it to the range and got wild groups, like 16”
I switched scopes and ammo - same

I brought it to the gunsmith, he Went thru the gun, redid the scope rings and put his precision scope on it
Bore sighted it, shot it with and without the suppressor

Same irregular shooting, luck to hit a 2’x2’ target

He looked thru the barrel with a borescope, it looks like a new rifle, the inside of the suppressor looks fine too
We have a call into CZ
The gun smith doesn’t know what to do next

Any ideas ?

Make sure the barrel is properly free-floated. The front 3" or so of the fore-end on my CZ 550 was very slightly warped and was touching the barrel. A bit of sanding solved my problem. I also glass-bedded it.

Also, does yours have the 2-stage trigger? if so, are you using it as a two stage or as a single stage? Mine has a single stage and although I've never shot a CZ 550 w/ a 2-stage, perhaps it's a bit heavy if you're shooting it as a single stage and it could possibly affect accuracy.

Serious question - are any bullets going sideways through the target?

Id send it back if its shooting that poorly and you have a competent gunsmith looking at it already. Something is way out of spec somewhere. Im a little surprised your smith couldnt pinpoint it though. Oh by the way, forend contact isnt going to affect accuracy to the point you are getting 16" groups. Does your smith have a bore mic? Maybe it was bored out to .375... Your rifle should also have the dual recoil lug. I neutral bed to the second recoil lug and freefloat forward of that lug. Also, you dont have to use that trigger as a set trigger. That feature can be adjusted out of it and you can easily adjust it down to a 2.5 pound pull wt. Something mechanical is way out of spec with your rifle. Do yourself a favor and send it back.

Have you tried it without the suppressor? If you get the same accuracy without it, then you know 100% it is the rifle.

Measure the bore.

In what configuration id CZ make a 550 9.3x62 with threaded barrel?

https://www.gunsinternational.com/g...-barrel--free-ammo-.cfm?gun_id=100763201


this one

no keyholing

shoots poor with and without the suppressor

we don't have a bore mic, off the muzzle the calipers measure 0.356; but with lands and groves its hard to say what we are measuring


We haven't heard back from CZ yet

The factory test target look OK?

Yes, was like an inch group

I still have that someplace

New? By all means send it back, assuming they will take it, if for no other reason than you shouldn't have to pay a smith to chase down a major issue like that. And let them look at it before something you try voids the warranty.

16" is horrendous.

Yes. Unless something was "rattling loose" I would only expect undersized projectiles or muzzle end damage to do this.

Which ammo did you try?

I've got the 308 version of the 550 and it is a tack driver with 168s. Maybe magazine box is binding or something is loose somewhere. Hope you get her shooting again, accurately that is.

PPu & hornady

Different lots too

Thanks everyone for your help

It’s extremely frustrating to wait 14months for the suppressor

Then wait for the snow to melt

Then find out it can’t hit the barn from 30y away

I would take the rifle to another gunsmith. If the first one can't figure out what is causing 16" groups and doesn't know what to do next I would move on.

Assume groups were shot at 100 yards?

I wouldnt even be happy with 16" groups at 1000 yards.

Any update?

I'm interested to know, as well. I've 4 CZ550's and they all hold less than an inch at 100 (well, the Lott depends more on me that day than the rifle......)

Well the gunsmith and I gave up, hunting seasons have started here

I found the receipt and CZ has a 5yr warranty on the rifle except for the wood so I have started a warranty claim with CZ

I suspect nothing will happen fast, but I will post the results of what they find

looks like I will be back with my ol' reliable '06 this Elk season

I had a stock crack on my cz527 carbine. They paid shipping, and replaced the stock with a excellent grain and figure upgrade. Turn around was good, I was very satisfied with the outcome.

Did the crown get messed up when the barrel was threaded for the suppressor?

Very odd...550s are notoriously accurate. Great barrels that are hand lapped and actions that are check for concentricity. I have 3 and all three envisage squarely on the front mugs AND the rear. Keep us posted

Here is the update:

I sent it back to the factory
They took it back on warranty, turned it around fairly promptly
They sent back a test target and a report: Cleaned old grease, PASSED, the target showed 1.3" groups with 286g S&B ammo

I mounted my inexpensive Walmart Nikon 3x9 and took it out
I shot PPU 286 and got 1 1/4", 2220 fps
Hornady 286 same 1 1/4", 2260fps

then I ladder tested some handloads, R17 powder

these were my tightest 3shot groups & velocity

Barnes TTSX 250g 3/4" , 2635fps
Nosler 286 partitions, 1/2" groups, twice, 2500fps, hotter load 2600fps 1 1/8"
Nosler 250g Accubond, 3/8" group, 2670fps, hotter loads opened way up

not bad velocity for a 20" barrel

I did 21 3-round groups, the average with what it did like and what it didn't like was 1 1/4"

If you only feed it what it likes best its a less than 1" gun

All it was was a dirty bore? Sounds like you need a new gunsmith.

Crown

Every CZ I've owned has been insanely accurate.....after some tinkering. The 204 Ruger almost went down the road due to poor accuracy. Turns out the barrel would foul out after a few shots. Some graphite in the bore helped greatly. Rifle shoots 3/4" groups at 200 yard.

I have a hard time believing That a dirty barrel did that.
They shot it at factory. 3rounds?
Then it Sat in your safe until you shot it and you got 16” groups.
Seems odd to me

So what did the resport they sent back say ?

Yeah no schidt. The op doesn't know how to clean a barrel either? Seems odd that a dirty barrel would cause 16" groups and then a clean bore would produce slightly over moa.

Kind of hard to swallow isnt it.

You could always rebarrel.

I'm waiting to hear back on my CZ550 Ultimate Hunting Rifle 300 Win Mag.This rifle never shot that well as I expected.Just been setting in the safe the last few years.I just got a bore scope and this is what I found.The last two inches at the muzzle end looks like this.I can even see it with a naked eye if I look in the end of the barrel with a flashlight.Not what you would expect when they make this claim on the rifle.
The CZ Ultimate Hunting Rifle (UHR) is a new CZ 550 based rifle in .300 Winchester Magnum that comes in under 8 lbs, and includes a minute of angle accuracy guarantee to 1000 yards. By maintaining quality control standards unheard of in the industry, the Ultimate Hunting Rifle delivers a level of accuracy formerly only available from high-end custom riflesmiths.

Wow, just wow!

They should rebarrel that one for you... just send them the pictures and I’m sure they’ll fix it.

They just moved their repair center from Kansas City, to Dallas Tx.. I’m not sure if they have officially pulled the switch, but they are moving the headquarters, and not hiring people here anymore....

That barrel should have never passed the pre-check a gunsmith does before installing a new barrel, provided you do one... I slug all my new barrels, and scope them as well.
Bummer.

Should hear back just any day.Sent pictures after I emailed them.This was what I got before I sent pictures

Note that the barrel is hammer forged then hydraulically lapped so some imperfections are normal inside the bore. However they are neither drilled nor cut, so no tool marks other than from the metal of the barrel being hammered into the mandrel should be present from the factory.
You can send the pictures to this email and we can inspect them here to see if they are out of the ordinary.

I'd say this is out of the ordinary

CZ has always been great warranty wise to me. i bought a cz 452 american in 17mach2 that had a ring in the barrel about an inch or so down. they emailed me and asked what i wanted to do. well i wanted the same rifle as a replacement. they didn't have anymore so i opted for the then new 17hornet in the cz 527 american.i'd still love to have a nib 452 in 17mach2 and am constantly on the look out.
Big Ed

Looks like they couldn't decide on cut or button rifling and did both.

Hydraulically lapped? I guess it is possible and if so the machine went haywire.

Have you looked into how the blanks that are forged onto the mandrels are manufactured?

You would think they would inspect the barrel before putting it on a rifle. The rest of the bore looks fine,it's just the last two inches on the muzzle end.

It’s probably where the machine grabs ahold of the barrel.

You always see weird stuff right at the end - you can’t lap to the very end, and some times they put cuts and or other tool marks on the outside from clamping down on them.
Unless they forgot to cut off the barrel at the right length... it’s wrong.

I thought they lapped the blank before putting it in the hammer-forger. That looks like the mandrel spent some time at the beach.

Stuff happens, though it's a major pain for those it happens too. Hopefully they'll get it right.

Curious what cz will do.
Had a hell of Time getting through to them today