CZ 455 Accuracy - Not what I expected

Chilly807 said:
If you look at firing pin imprints from high end 22 target rifles, i.e. Walther or Anschutz, it'll give you something to work toward.

The CZs are particularly prone to this IMO, I think they use the same FP profile in all their rimfire bolt actions, regardless of caliber. I may be wrong about that, too.
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CZ 455's use the same firing pin configuration for all three common calibers -- .22LR, .22WMR, and .17HMR -- and as a result reshaping the firing pin may be helpful so that it works best for your particular caliber. Of course that may result in the firing pin not being the optimum shape for other calibers should a barrel/caliber swap be made.

As far as what the firing pin strike looks like on an Anschutz target rifle, here's a photo from this morning from my rifle. Walther KKM strikes look very similar.

 
Chilly807 said:
Photobucket is having issues tonight, so no pics right away. I do have before and after pics of both cases and the firing pin itself. The mod took about an hour and a half and a dozen tear down and reassembly cycles of the bolt.
If you remove too much material, you're replacing the firing pin, better to take off a little bit then try it.
Some have better success than others. If your rifle has no ignition problems in the first place, you won't see any improvement. Mine apparently did, although the only indication was inconsistent shooting, never a fail to fire in over 1000 rounds.
If you look at firing pin imprints from high end 22 target rifles, i.e. Walther or Anschutz, it'll give you something to work toward.

The CZs are particularly prone to this IMO, I think they use the same FP profile in all their rimfire bolt actions, regardless of caliber. I may be wrong about that, too.

Ronnie is spot on with his comments above. If you're going to try this, or any mods for that matter, try one change at a time, then shoot the rifle for a while to evaluate what effect it had, if any.

I never would have suspected it would make any difference at all until I started reading about other's experiences. It definitely changed the 452 I have for the better. Once I have some more results from shooting 50 to 100 yards, I'll change my 455 to match the 452. 25 yard results show a definite improvement, and initial testing at 50 looks better too. I don't base my decision on group size only, but rather on scores from various targets I've shot before. None so far have been the same or worse, all have shown improvement.
Maybe pics over the next few days, time permitting.
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didn't read you post other then photobucket is having issues tonight, photobucket has had issues for about 2 weeks now since the hacker attacks. I've been on photobucket every night since then & it keeps freezing & I have to reboot 2-3x just to get a few pictures done. Pain in the @ss
 
horseman2 said:


I have other pictures but am not certain if they were from the American or the Varmint.
I do believe it helps. When I had taken the reshaping as far as wanted the only thing done after was to removed the corners so the imprint followed the contour of the rim. This was also suggested so that the brass was not going to be pierced. The bolts were disassembled countless times but not enough to try it in the dark!
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I just don't want to screw this up, as pins are $80+ to replace. I do have a replacement YoDave stricker pin giving 10% harder strikes.
 
IMO it's a little too soon for the OP to be thinking about firing pin mods as that is more so something to do to help a good rifle shoot a little better rather than attempt to cure a gross accuracy issue. As he is considering trading/selling the rifle if it can't be figured out, I'd be hesitant to do any permanent mods to it. Regarding the firing pin, the design is a compromise to handle the different calibers with the switch barrel design. CZ did a small goof though as the striker tip extends well beyond the rim edge of even a 22 WMR, the drill hole through the bolt cuts through the recess and bolt nose. If you mod it to a particular caliber, that striker is married to that caliber.

With the info that the OP did not adjust the scope at all, the groups shifting to the right are puzzling as my experience with the action screws coming loose while shooting just spreads the grouping randomly left/right/up/down rather than a neat shift in one direction. Perhaps I wouldn't entirely discount shooting technique here.

If we re-visit the defective factory barrel on my 455 we see the major shot dispersion is the vertical component, negligible horizontal and no shifting POI. Bedded rifle with good scope and all screws properly torqued.



For the OP's rifle I'm leaning towards a couple things to sort out. Scope (try a different one to see if any difference), Scope rings (as someone pointed out while the base might torque down, the fit may not actually have bite on the dovetail.) Loose action screws (check them after shooting a few groups) ammo selection (barrel could be picky, not much "quality" ammunition tested yet) and finally a good look at shooting technique, breaking your wrist can pull those groups off target.

A barrel issue (what I've mostly dealt with ;) ) holds POA & POI in a properly setup rifle, just spreads the shots in a particular dispersion pattern around it.
 
Thanks RabidM4U5, I will try all of your suggestions above. Looks like you have your hands full with those groups. I feel your pain. Anywhere locally to buy premium ammo? I tried buying some online thru Hirsch but had a bunch of problems.
 
shellbird01 said:
Thanks RabidM4U5, I will try all of your suggestions above. Looks like you have your hands full with those groups. I feel your pain. Anywhere locally to buy premium ammo? I tried buying some online thru Hirsch but had a bunch of problems.
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Center-X is pretty decent ammo. It it can't shoot with that, there must be other issues.
 
A big thank you to RabidM4U5 (and Gunnutz). We met at the range today, he brought some premium ammo, it all shot well except SK HV. RabidM4U5 installed a shim 3" up the barrel. Quite a difference. It's not going to win any prizes but it seemed to shoot between .5 & .75 with the shim installed. I'm much happier now! Thanks RabidM4U5!

http://imgur.com/a/0nmOo
 
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Not unusual. Both of my CZs have been "shimmed" this way. The 452 is shimmed directly below the sling swivel stud, the 455 roughly three inches from the receiver. I used 5 minute epoxy with flour added to stiffen the mixture.
I followed some advice and waxed the barrel channel first to make it easier (maybe!) to remove the shim if it didn't work out.
One of the best shooting rifles I have, a Tikka T3 in 308, has a similar pressure point under the barrel from the factory.
 
Chilly807 said:
Not unusual. Both of my CZs have been "shimmed" this way. The 452 is shimmed directly below the sling swivel stud, the 455 roughly three inches from the receiver. I used 5 minute epoxy with flour added to stiffen the mixture.
I followed some advice and waxed the barrel channel first to make it easier (maybe!) to remove the shim if it didn't work out.
One of the best shooting rifles I have, a Tikka T3 in 308, has a similar pressure point under the barrel from the factory.
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Thanks to RabidM4U5 for that, it's got to be the cheapest accuracy gain there is. I have a Tikka T3 hunter in 30-06, it's a great shooter.
 
Well.... I ground the firing pin to be inside the rim just like the pictures you guys sent. I'll see tomorrow if it makes a difference, I also have some Federal Ultra Match to try $$$. I got a note back from Tactical ordinance their to busy to do the pillar & glass Bedding. Stelios will cost $450. Thats almost the worth of the gun, gonna have to think about that one. Any other things to try, maybe loctite the barrel, another shim further down the barrell?

FYI - I also bought a tipton .20 after using RabidM4U5's. It clears the bolt guide and is still plenty snug in the barrel for cleaning.
 
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I really wish I kept all the targets from the last 2 months........
I am playing with action screw torque and shooting groups at 100 yards, watching the results of the groups with just 1 inch pound more torque applied to the screws is unbelievable, thankfully there has always been a great number of witnesses to see the results, from 2.25 inch groups to 3/4 inch groups using the same ammo, repeatable over 3 rifles now so it's not just a fluke or a barrel getting seasoned......My eyes were opened by the results and I even went as far to upgrading my torque driver to one that is set just like a torque wrench over the big fat red line of the wheeler, although the wheeler works I wanted something with far more finesse
 
How many inch lbs did you use? I've been told 24 is max without pillars or the stock will get crushed. My stock is the Canadian edition in Beech. I have the wheeler, I agree it's not accurate to 1 in/lb by any means.
 
start at 15, 20, 24....pick the best one and then fine tune
working with anshutz rifles this week and 40-41 and 42 respectively were the sweet spots, anshutz recommends 45 and the groups were more like patterns
 
shellbird01 said:
. Stelios will cost $450. Thats almost the worth of the gun, gonna have to think about that one. Any other things to try, maybe loctite the barrel, another shim further down the barrell?
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Ooof! No way I'd spend that to pillar/bed a CZ stock. Maybe on a Pro-Varmint or Klinsky or other custom stock for a match grade custom build... But for a factory rifle/stock a $30 DIY job is all it's worth. IMO, you could go all out on the tweaks and mods on your rifle but I believe the root of the issue is the quality of the barrel itself. I remember it didn't even give one group in the 0.2's or 0.3's. Only one in the high 0.4's. I've spent too much time going all out on the mods with rifles that would never improve because it was the barrel that was the issue. I recognize the pattern in performance when dealing with such issues and I'm sorry to say but I think that barrel has gotta go if you're not happy with the 1/2"-3/4" we got it down to. Too much work and money involved and all you might get is improvement to 0.4-0.6". That $450 would go a long way towards a nice, custom barrel for it.
 
In the spring time there is a Canadian custom barrel maker who may be tooled up and ready to make .22 LR, I'll keep you guys posted on that. Just FYI the Lilja barrels are no longer EPS chambered, they are Bentz chambered. They should still shoot well but it is a definite downgrade from the true match chamber. Alberta Tactical Rifle is an established Lilja importer they'd be the first ones to talk to. A certain other listed Lilja importer in Ontario I cannot recommend dealing with as they've been extremely unprofessional with a terrible customer service attitude towards me. So bad, in fact, that I have indeed taken legal action against them. That's about all I can say until the trial is over.
 
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