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  #1  
Old 11-27-2017, 02:01 PM
sbsyncro
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If you're having accuracy problems with your CZ455...



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Earlier this past summer I got myself a shiny new 455 American with both the 22LR and 17HMR barrels. I soon added a 22WMR barrel as well. Excited to see the legendary accuracy of this gun, and to figure out what ammo it liked best, I spent several weeks and hundreds of dollars on all the high end and bulk 22LR I could lay my hands on.

I posted initial results back in July:

High End ammo results: https://www.rimfirecentral.com/forums...d.php?t=981049

Bulk Ammo Results: https://www.rimfirecentral.com/forums...d.php?t=965921

In both of those tests, I found ammo that seemed to be more consistently accurate (CCI Stinger and Federal Auto-Match), but my results seemed to vary a lot, even taking into account conditions and my own skill limitations. I was never able to achieve really good accuracy.

Since then, I stumbled across two issues that affected my accuracy out of the box with the gun, and if you're having problems with accuracy, I suggest you check these issues yourself.

The main problem seemed to be that the gun was overly sensitive to hold.
It seemed that if I changed my front rest on the stock - pulling down or pushing to the side slightly in order to center on the target, my results would be less consistent than if I lined up the cradle perfectly on the target and just rested the butt against my shoulder and steadied the rifle with my shooting hand. Even then I seemed to have inconsistent results, even when "feeling good" about a series of shots. (you know what I'm talking about - that feeling right when the gun goes "bang" and you know it was perfect.)

Issue #1 - contact between the barrel and the stock

In the process of disassembling and cleaning the gun after the first few hundred rounds as well as swapping barrels, I noticed that I could not slide a dollar bill/piece of paper between the barrel and the forestock. This ended up being a combination of both (a) not enough clearance and (b) over-tightened action screw (see below). Using a wooden dowel and some 80, 120, and 220 grit paper, I cleared out a mm or so of wood to allow the barrel to completely free-float.

Issue #2 - over-torqued action screw, magwell screw, and mis-routed trigger guard mounting slot
When I first disassembled the gun to swap barrels, I noticed that the front action screw (the one that goes through the front of the trigger guard) was very tight and the stamped metal was distorted a tiny bit. I pulled out the manual that came with the gun and it says the torque spec is 6 nm. (Yes, that's right - over 50 inch lbs!!)

I also noticed that the front edge of the trigger guard was not laying flat in the routed-out wood of the stock, which was causing the action screw to "pull down" on the trigger guard. I used some small files and popsicle sticks with sand paper to clearance and flatten the wood mounting surface and then reassembled to the "factory spec" of 53 inch lbs. I didn't even get to 30 on the dial before I knew it just felt wrong (and I could feel the trigger guard starting to deform again).

Instead I installed it "hand tight" (about 18 inch lbs or so). I also loosened and re-torqued the front magwell retaining screw, which also seemed very tight.

With these two changes, accuracy improved DRAMATICALLY. I now feel like it is ME controlling the accuracy rather than the gun. Here is my latest results using Aguila Super Extra. According to everyone, "high velocity" rounds are inherently less accurate in a 22 LR, but for the ammo I had on hand with me yesterday, this was the most consistently accurate aside from the Aguila Rifle Match and Aguila Pistol Match, which were very similar



In fact the Aguila Super Extra were about twice as accurate as the Eley Target, Eley Match, and RWS Target Rifle, & RWS Rifle Match!
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  #2  
Old 11-27-2017, 02:12 PM
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flylo
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I've been using Aquilla Super Extra Standard, the cheapest thing you can buy & nobody believes it, Thank You!
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Old 11-27-2017, 05:15 PM
Gmww
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Quote:
Originally Posted by sbsyncro View Post
Earlier this past summer I got myself a shiny new 455 American with both the 22LR and 17HMR barrels. I soon added a 22WMR barrel as well. Excited to see the legendary accuracy of this gun, and to figure out what ammo it liked best, I spent several weeks and hundreds of dollars on all the high end and bulk 22LR I could lay my hands on.

I posted initial results back in July:

High End ammo results: https://www.rimfirecentral.com/forums...d.php?t=981049

Bulk Ammo Results: https://www.rimfirecentral.com/forums...d.php?t=965921

In both of those tests, I found ammo that seemed to be more consistently accurate (CCI Stinger and Federal Auto-Match), but my results seemed to vary a lot, even taking into account conditions and my own skill limitations. I was never able to achieve really good accuracy.

Since then, I stumbled across two issues that affected my accuracy out of the box with the gun, and if you're having problems with accuracy, I suggest you check these issues yourself.

The main problem seemed to be that the gun was overly sensitive to hold.
It seemed that if I changed my front rest on the stock - pulling down or pushing to the side slightly in order to center on the target, my results would be less consistent than if I lined up the cradle perfectly on the target and just rested the butt against my shoulder and steadied the rifle with my shooting hand. Even then I seemed to have inconsistent results, even when "feeling good" about a series of shots. (you know what I'm talking about - that feeling right when the gun goes "bang" and you know it was perfect.)

Issue #1 - contact between the barrel and the stock

In the process of disassembling and cleaning the gun after the first few hundred rounds as well as swapping barrels, I noticed that I could not slide a dollar bill/piece of paper between the barrel and the forestock. This ended up being a combination of both (a) not enough clearance and (b) over-tightened action screw (see below). Using a wooden dowel and some 80, 120, and 220 grit paper, I cleared out a mm or so of wood to allow the barrel to completely free-float.

Issue #2 - over-torqued action screw, magwell screw, and mis-routed trigger guard mounting slot
When I first disassembled the gun to swap barrels, I noticed that the front action screw (the one that goes through the front of the trigger guard) was very tight and the stamped metal was distorted a tiny bit. I pulled out the manual that came with the gun and it says the torque spec is 6 nm. (Yes, that's right - over 50 inch lbs!!)

I also noticed that the front edge of the trigger guard was not laying flat in the routed-out wood of the stock, which was causing the action screw to "pull down" on the trigger guard. I used some small files and popsicle sticks with sand paper to clearance and flatten the wood mounting surface and then reassembled to the "factory spec" of 53 inch lbs. I didn't even get to 30 on the dial before I knew it just felt wrong (and I could feel the trigger guard starting to deform again).

Instead I installed it "hand tight" (about 18 inch lbs or so). I also loosened and re-torqued the front magwell retaining screw, which also seemed very tight.

With these two changes, accuracy improved DRAMATICALLY. I now feel like it is ME controlling the accuracy rather than the gun. Here is my latest results using Aguila Super Extra. According to everyone, "high velocity" rounds are inherently less accurate in a 22 LR, but for the ammo I had on hand with me yesterday, this was the most consistently accurate aside from the Aguila Rifle Match and Aguila Pistol Match, which were very similar



In fact the Aguila Super Extra were about twice as accurate as the Eley Target, Eley Match, and RWS Target Rifle, & RWS Rifle Match!
Good post. Once I find ammo that my particular gun likes, I then play with various torque settings to see what is the sweet spot torque for that ammo is. It's amazing to see how several in/lbs. will change the group size.
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  #4  
Old 11-27-2017, 05:32 PM
sbsyncro
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Hereís a couple more results from yesterday. Avg 1.2 MOA at 50 yds (0.6Ē)

I havenít decided whether I want to play with torque specs yet. I think Iíve reached the point where my own skill is the limiting factor. Itís fantastic knowing that Iím in control now, though!
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