CZ 455 Accuracy - Not what I expected

Kody said:
When you re-install the barrel just follow the instructions in the manual. Make sure the matting surfaces are perfectly clean and torque both barrel grub screws somewhere between 30 and 35 inlbs.
K
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If you don't already have an inch pound torque wrench, now's a good time to get one. The CZs are somewhat torque sensitive on the action screws as well, so you'll be using it more than once.
I use the Wheeler FAT wrench (screwdriver actually). Cabela's and Amazon both sell it, mine came from Amazon. About $80 IIRC. There are more expensive, more accurate wrenches I'm sure, but this one does the job for me.
 
shellbird01 said:
Cleaned the barrel with a .22 dewey rod, a .22 pistol jag with a very thin patch, then a .22 pistol brass brush - only pushed thru the breach & removed once thru the muzzle. The carbon ring (i assume) at the chamber / throat came off well, now it's sitting over night with hopes #9 in it (as per the directions on the label). The barrel looks shiny & clean from breach to muzzle.
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Will be interesting to hear how it shoots now. Make sure you shoot a few fouling shots before you pass judgement on it. I find a freshly cleaned barrel with a bit of oil in it, will produce a flyer or two.

I have not followed this thread once it turned to cleaning. I find there are as many different opinions as there are posters on that subject, and I stay out of it. If carbon is a problem in your gun, then you might want to get a bottle of Gumout Regane Complete Fuel System Cleaner. Canuck Tire has it and frequently puts it on sale. Be careful with it though as it probably is not kind to the varnish finish on a gunstock.

Not sure if anyone posted this link on Rimfire Cleaning. It is probably the bible on the subject. However, I have not found it to be all that necessary. Boresnake is as sophisticated as I get. But it does seem that you have experienced the dreaded carbon ring. I will have to inspect my gun a little closer, but I don't think I have ever seen anything like it.
 
Some place I read an article about breaking in a 22.
Clean, fire 100 lead bullets, clean, fire another 100 lead bullets, clean, fire 100 more lead bullets, clean and now it is broken in.
Lead ammunition was specified but it was one man's opinion. Most imperfections should be removed at this point.
Could the same thing be accomplished in ten rounds by dipping the lead portion of the bullet in JB paste and firing them.
With a centerfire rifle bullets were made with varying degrees of fine grit imbedded in the bullet and the shooter stared with coarsest and proceeded to the finest. Perhaps five rounds of each and IIRC "hot" was one of the words to describe this process.
Your choice and "takes your chances"!
 
These are the groups I shot yesterday after 5 foulers, CCI Std velocity, sorted by weight 50 yards, shooting prone off my truck cover with rests, as range is only open Saturdays, proper bench shooting would improve groups I believe:
#25: 1st 3 were the ragged hole, 4 flyer made strange sound?, 5 just above.
#24: 1st on the mark, 2-4 decent group but POI changed, 5 into #23
#23: skipped due to flyer from #24
#22: Reduced to groups of 3 - no comments
#21: Reduced to groups of 3 - no comments
Top: Reduced to groups of 3 - no comments
This is much better than last week, is heat an issue when shooting .22? Should I allow time for cooling between groups? Should I shoot groups of 3 or 5?

Thank you to everyone for your comments & cleaning tips. I think I need to keep this clean and keep experimenting with ammo. Should I clean again or let if foul for 500 rounds?
 
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shellbird01 said:
These are the groups I shot yesterday after 5 foulers, CCI Std velocity, sorted by weight 50 yards, shooting prone off my truck cover with rests, as range is only open Saturdays, proper bench shooting would improve groups I believe...

This is much better than last week, is heat an issue when shooting .22? Should I allow time for cooling between groups? Should I shoot groups of 3 or 5?

Thank you to everyone for your comments & cleaning tips. I think I need to keep this clean and keep experimenting with ammo. Should I clean again or let if foul for 500 rounds?
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Unless it was quite windy/gusty I would not be happy with that. CCI standard velocity is OK ammo, but not great. I would try and get some Lapua Center-X, SK Rifle Match, or SK Standard Plus to try. They are all basically the same ammo, just different quality control levels, and as a result the price. The Standard Plus is likely to have more flyers than the Center-X. CCI Green Tag may be worth a try too if you can find it.

If I am testing ammo I shoot a box of 50 using two as foulers, and then 24 groups of two. However, I think you are more into testing your gun than the ammo, although you do need to step up a better ammo. Groups of 5 is find to test your gun, and probably the right way.

Not sure if you have a heavy barrel or light one? With my heavy barrel I shoot as fast as I can single load each round and re-aim at a relaxed rate. The barrel basically stays somewhat warm, and never gets hot like a centerfire can do.

There would be no harm in cleaning now. Just remember to shoot at least a couple of foulers as a squeaky clean barrel often throws a flyer or two before it settles down.

I have forgotten. Is this a new gun? I would be considering sending it back to the manufacturer or asking for a replacement.
 
Hmm couple of thoughts seeing that target you were off to a good start! The "strange sound" and flyer relate to ammo quality, inconsistent powder/primer charge. Shoot a clip of Remington Thunderbolts and it's like playing a musical instrument ;) so that tells me your CCI isn't a good lot and you'd need to shoot a lot of it to see how often you get fliers like that but it may be best to move on to another ammo brand. It's normal to see POI walk around a little bit but that is extreme! Made me think your scope might not be holding zero as it looks like you adjusted for the shift then it started happening again during the next two groups. Or... scope rings/mount working loose? Action screws working loose? Yes, you may have torqued them before starting to shoot but it can happen without you realizing ;) That's the point in the shooting session where I would go over everything with a torque wrench again just to be sure nothing got loose because it has happened to me several times so I always bring the tools with me.

I don't feel overheating is an issue shooting Standard Velocity .22, you can shoot boxes of ammo and only have the barrel get "somewhat" warm to the touch. It's not strictly necessary to clean again after less than 50 shots, but if you're going to try different ammo then a couple dry patches down the tube is a good idea to get the different lube out. If it makes you feel better there's no harm in giving it a few more passes with the brush, those carbon rings can be pretty resilient and tbh you can't really tell if they're clean just by looking down the bore by eye. At the very least you need a jeweler's loupe or magnifying glass, mirror angled to see into the chamber and light. I prefer 5-shot groups but if 3 aren't grouping nicely well "nobody ever made a group smaller by firing another shot at it".

If you have another scope that you know is good I'd think about putting it on for the next shooting session. I think there's a good chance this rifle can come together with possible scope and action screw torque issues squared away and a good ammo testing session.
 
- The scope is a Leupold VX-III 4.5 - 14 with AO - Range 50 yards. Fat wrench: Bases 25"lbs, rings 15"lbs & Action screws 20 "lbs. I have another scope I can try.

- Last time I used Eley Target & Eley Match they shot much worse than CCI SV - I will try them again. Where can I order SK +, Midas, Lapula. Nordic?

- It was not windy ~5kmph. It is a New CZ 455 Canadian Sporter with ~ 2K rounds thru it. I will clean it more & try to get a borescope thru it.
 
I'd be surprised to see a Leupold not holding zero, it's just that group pattern due to loose action screws/scope mount would be random all over the target, whereas here I'm seeing a shift to the right. If you get the same thing happening with a different scope then at least we've checked off the list that it wasn't the scope. 20in/lbs on the action screws can easily loosen off over several groups at first, I've had to tighten it a couple times before it held steady at that setting.

SK+, SK Rifle match and Lapua Center-X are sold out all across Canada at the moment. Delivery expected "soon". Nordic and Hirsch have limited amount of Midas + and X-Act still available. Target Shooting Products has a good selection of Eley and RWS in stock but it sounds like Eley is not a good match for your rifle, or was it the Remington/Eley branded ammo? I haven't had much luck with it either in several rifles.
 
RabidM4U5 said:
I'd be surprised to see a Leupold not holding zero, it's just that group pattern due to loose action screws/scope mount would be random all over the target, whereas here I'm seeing a shift to the right. If you get the same thing happening with a different scope then at least we've checked off the list that it wasn't the scope. 20in/lbs on the action screws can easily loosen off over several groups at first, I've had to tighten it a couple times before it held steady at that setting.

SK+, SK Rifle match and Lapua Center-X are sold out all across Canada at the moment. Delivery expected "soon". Nordic and Hirsch have limited amount of Midas + and X-Act still available. Target Shooting Products has a good selection of Eley and RWS in stock but it sounds like Eley is not a good match for your rifle, or was it the Remington/Eley branded ammo? I haven't had much luck with it either in several rifles.
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Hey RabidM4U5, it's not rem/eley, it's eley club & match.
 
I believe the CZ uses dovetails in the receiver? Is it possible you don't have the correct size dovetail mount? Savage supplies Weaver style bases on their Mark II's. Some owners have found the Savage supplied bases to be just a tiny bit more narrow than the true Weavers. That combined with certain scope rings that do not adjust down as far, can make for a loose fit, regardless of the amount of torque you put on the screws.

When you get those flyers to the right, do subsequent shots come back to the left again? Or, are you adjusting the scope? If they go right and stay right, that is pretty much for sure a scope or scope mount issue.
 
I haven't been adjusting the scope, just zero at 50 yrds on the centre of the target, no compensation. I have hawke rings 11mm I believe.
 
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Chilly807 said:
I think the single biggest improvement I've seen in my 452 has come from re-shaping the tip of the firing pin. Prior to that, most of my misses were vertical. Now they're evenly distributed around the point of aim and there are less of them. My 455 will get the same treatment in a few weeks when I have some extra time. I don't swap barrels, it's 22LR only.
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How did you reshape it? Any pics of this before & after?
 
ronnie01 said:
This will keep you busy reading works well and easy but must be finished with a fine polished surface to reduce stress marks in brass.Diamond flat hone does it very nicely.I sharpen Asian chef knives and others as a sideline and that is where the flat diamond hone came into play.
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I take it you did the Calfee modifcation? I tried it on my Savage, and it really did not improve accuracy that I could measure. However I was getting 1/4" at 50 before the mod, so there was not much to gain. Here was an interm result that did not have the final polish on the pin. However you can see the much lighter hit on the very outside of the rim.

22Case2.jpg
 
Ron AKA said:
I take it you did the Calfee modifcation? I tried it on my Savage, and it really did not improve accuracy that I could measure. However I was getting 1/4" at 50 before the mod, so there was not much to gain. Here was an interm result that did not have the final polish on the pin. However you can see the much lighter hit on the very outside of the rim.

22Case2.jpg
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The outer rim area is a waste of energy as there is no primer in that area at all.When the rim case is made there is no void there for primer to migrate into.The mod suggests to eliminate this area and move the footprint inwards to have a more effective ignition of primer. Some state better ignition on their CZ'S.There is a lot of reading on the mentioned forum,one would have to really study the results.My 452 appeared to reduce vertical strings,but they never that much of a problem.This should be one of the tweaks that is done on it own with no other to reveal any improvements while playing around.The 455 is another challenge as they also use the same setup for 17hmr and that rim is larger so a mod on a 22lr scenario may cause some problems with 17hmr and win mag.That in return the pin may only be effective on the 22lr cartridge.

R
 
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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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Chilly807 said:
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.
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Calfee's claim is that the modified pin profile to concentrate the strike further in from the rim, and lighter on the rim, holds the case from moving during the firing process.
 


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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