22wmr Cz 512 semi automatic accuracy issues with moderator at 100 meters

[Birdshot]

Hello folks,

Attached is a pic of a target I was shooting at 100 meters away using a 4-12x40 scope.......10 shots with mod off and 10 shots with mod on........the shots on the top right hand side are with the mod off and you'll notice the groups have opened up considerably........what do you think the reason for this is

 

[Kane01]

Could be a number of things really, what ammunition are you using? I know some rimfires just dont like certain brands/products of ammo.

 

[billy_boyle_2010]

It would be easier to compare group sizes if you had used seperate bits of paper, with the mod on and off.

But if the 10 closest holes- some of which are touching- are with the mod off- around 1-1.5"- and the other 10 are around 4"+- then that doesn't look right.

It could be the rounds are clipping the mod- or getting super close to it- and that's affecting accuracy. Is the mod def .22 size ? Not a .17 which has been shot out ?!

If its def the right calibre mod- perhaps it's not screwing on properly- so its out of allignment? Is it a factory thread on the barrel ? Can you fit another mod- perhaps a larger one- and test?

 

[Stover Rover]

I have a CZ512 22WMR, but it is the wooden stocked open sights version, unthreaded. Accuracy is very good at 1-1.5 MOA at 100 yds. Do you have the wooden stocked variant or the tactical?

 

[Birdshot]

I have a CZ512 22WMR, but it is the wooden stocked open sights version, unthreaded. Accuracy is very good at 1-1.5 MOA at 100 yds. Do you have the wooden stocked variant or the tactical?

Hi I have the wooden stock version I fire 40 grain Remington's ......and I know what you're gonna say about the tactical version....... there's a threaded block on the barrel that holds the the barrel hand guard in place only issue is the there's a slight gap between the barrel block and the barrel guard and are not sitting flush....... when bolting on the barrel gaurd there is strain put against the barrel causing bullets to fly in different directions

 

[3595wilk]

Is the moderator acting as a balancing weight and keeping the barrel more stable when fitted? The way CZ have chosen to fix the barrel to the front furniture is a bit weird.....and does allow for different torque to effect the barrel.....especially as you can use a 2p coin to strip it.

I've got the same rifle, but chopped to a 16 inch barrel, and use an over barrel Wildcat on it. This seems to provide more consistency with it and I have a self imposed 125 yard max for it in the field as mine shoots around 1.25 to just over 1.5 MOA; and isn't particularly ammunition fussy. Never tried it moderator-less to test the theory, but just a thought.

For all its niggles, still love mine for daylight rabbit control.

 

[Birdshot]

Yeah love mine as well a very reliable wmr that'll cycle any load something that many manufacturers have struggled to produce it's nice having a 22 rimfire that can shoot flat upto 100m...........I'll probably play around with the fore end screw see if that makes a difference with the moderator

 

[Birdshot]

I striped and left the mod soaking in water and fairy liquid last night, gave it a thorough cleaning this morning and I noticed when looking straight down the mod through the holes (the ones that the bullet would travel through) that some of the holes had sharp distorted edges that weren't entirely round......I'm thinking would it be worth my while using a metal drill bit and gently smoothing the holes to make a cleaner edge?

 

[DesG]

I striped and left the mod soaking in water and fairy liquid last night, gave it a thorough cleaning this morning and I noticed when looking straight down the mod through the holes (the ones that the bullet would travel through) that some of the holes had sharp distorted edges that weren't entirely round......I'm thinking would it be worth my while using a metal drill bit and gently smoothing the holes to make a cleaner edge?

My 308 mod has a 9mm hole for a 7.62mm projectile. Not a lot of room for error. I noticed jagged edges on the baffles so I ran a 9mm reamer through it and the groups instantly tightened up. Give it a go. Also if you can, try another mod and see what happens.

 

[Smellydog]

I striped and left the mod soaking in water and fairy liquid last night, gave it a thorough cleaning this morning and I noticed when looking straight down the mod through the holes (the ones that the bullet would travel through) that some of the holes had sharp distorted edges that weren't entirely round......I'm thinking would it be worth my while using a metal drill bit and gently smoothing the holes to make a cleaner edge?

I wouldn't use a drill bit. Reamer.

 

[Birdshot]

Good news people, it was an ammunition issue. Every time I pull the trigger the bullet casing will eject itself from the chamber doing this causes a change in pressure in the barrel causing bullets to fly in any direction........the idea was to use lighter bullets as they'll travel through the barrel faster before the bullet casing is ejected........... heavier bullets are slower which cases the bolt to open before the bullet has left the barrel.....I used Remington 40 grain and have now ditched them .....I now use 30 grain hornady vmax and for a semi auto the results are unbelievable I'd say it outperforms my 17hmr........... I fired 4 shots at 100 meters

 

[old keeper]

I used a 512 for several years before passing it to my shooting mate. I always found it extremely accurate, the best semi I've ever had.

Was this the first time you'd used it? if not how did it shoot before?

 

[Birdshot]

I bought the gun in 2023......and only used 40 grain Remington bullets, the accuracy was ok at the beginning and I would strip and clean the gun after about 400 rounds, but as time went on I noticed it was starting to get larger unpredictable groups, attached below are 100 meter target pics when using the 40 grains, thats roughly when it was getting unpredictable with occasional flyers, if you look closely at the target you'll see a green square, that's where my barrel was pointed at on the target and the green circle was the most recent bullet fired.........Today was the day I used the 30 grain vmax and holy smokes was I impressed, I was on the verge of replacing the gun but that ammo saved it..............I think what happened was the gun was broken in with the 40 grainers and the bolt spring became more relaxed and not as tight over time resulting in a change of pressure in the barrel with the slower heavier 40 grainers..........

 

[Smellydog]

Hmmm that sounds like a wrong diagnosis.

I can guarantee you that it , the issue, is not down to bullet weight alone.

When a rifle fires the pressure should cause the cartridge to grip the chamber and stay put thus sealing it.
Only once the bullet has left pressure drops significantly to cause the case to release from the chamber and residual pressure operates the bolt.
Believe me, if your bolt was opening with the bullet still in the barrel you would know because your ears would hear an almighty pop and you would quite likely feel debris flying around.

Do you leave the barrel dripping in oil by any chance or over lube the action?

 

[Birdshot]

Definitely haven't left the barrel

Hmmm that sounds like a wrong diagnosis.

I can guarantee you that it , the issue, is not down to bullet weight alone.

When a rifle fires the pressure should cause the cartridge to grip the chamber and stay put thus sealing it.
Only once the bullet has left pressure drops significantly to cause the case to release from the chamber and residual pressure operates the bolt.
Believe me, if your bolt was opening with the bullet still in the barrel you would know because your ears would hear an almighty pop and you would quite likely feel debris flying around.

Do you leave the barrel dripping in oil by any chance or over lube the action?

Definitely haven't left the barrel dripping in oil......my cleaning routine has never changed and it still fired great with the hornady.........I was told that CCI make rimfire bullets for Remington, federal and various other companies.......I think I'll stick with the hornady from now on, they look like there better than the other brands

 

[Smellydog]

Definitely haven't left the barrel

Definitely haven't left the barrel dripping in oil......my cleaning routine has never changed and it still fired great with the hornady.........I was told that CCI make rimfire bullets for Remington, federal and various other companies.......I think I'll stick with the hornady from now on, they look like there better than the other brands

CCI, unless things have changed make the Hornady ammo!

 

[Smellydog]

If the case was moving the bolt back with bullet still in barrel you would see bulged case heads if not ruptured even!

 

[Birdshot]

If the case was moving the bolt back with bullet still in barrel you would see bulged case heads if not ruptured even!

I'm a wee bit skeptical to honest this is the link to a clock pistol being fired in slow motion now bare in mind this bullet being fired is most likely faster than my wmr and my wmr barrel is about 5 times the size of the clocks barrel.....if you look closely you'll notice the bullet is literally 1 cm out of the clock when it starts to eject the case..........I'm starting to think my my bolt was getting some kick while the bullet was in motion in the barrel

 

[Birdshot]

I've watched the video a few times and In fact the action of that Glock started moving moving before the bullet left the barrel

 

[Smellydog]

I'm a wee bit skeptical to honest this is the link to a clock pistol being fired in slow motion now bare in mind this bullet being fired is most likely faster than my wmr and my wmr barrel is about 5 times the size of the clocks barrel.....if you look closely you'll notice the bullet is literally 1 cm out of the clock when it starts to eject the case..........I'm starting to think my my bolt was getting some kick while the bullet was in motion in the barrel

Nope mate. The wmr is a lot faster than the Glock.
The case is not being ejected with the bullet one cm away from the muzzle. The mechanism is being unlocked first then the case is extracted via residual pressure not high pressure.
If your cases have no swollen or ruptured rims the bolt is remaining in battery as designed .