Smooth up CZ 550 bolt action

Discussion in 'Gunsmithing' started by Nhoro, Dec 13, 2018.

  1. Nhoro

    Nhoro AH Veteran

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    Hi All, Just thought I would share my experiment in smoothing out a brand new CZ 550 in .458 Win Mag.Please note this is what I did, it is not intended as a definitive how to guide, use this information at your own risk ! I may add or change things as I think about them. I searched the internet and couldn't find many details of what parts to polish and I may have left out something. I avoided the valve grinding paste/toothpaste method because I didn't want grit in my trigger/ejector/safety etc.
    Stage 1: This is what I have done so far, there may not be a Stage 2 because this has worked pretty well. I sat and cycled the action while looking to see what made it feel tight/gritty or hesitate. I also dropped the magazine and follower out- This made a huge difference. I examined the bolt and could see some marks/scratches from cycling the action. I decided that the magazine follower was the main culprit but the bolt could also smooth up, especially in certain key areas. I used 600 grit paper without fluid and a sanding block to keep edges sharp.
    In the picture below, you can see the angled corner (at my fingernail)with a chamfer on the left. The bolt rides up the chamfer and along the corner as you cycle it. I polished the left edge,chamfer and length of the corner with 320 and then 600 grit. I also polished up the sides so that the follower will ride more smoothly in the magazine. Using 600, it is pretty hard to alter any angles or mess anything up.
    IMG_5181.JPG
    Next I tackled the bolt. One key area is shown by my index finger. This edges rides up the chamfer on the follower and then the corner of the follower rides along the bolt from this point. I polished the edge and along the bolt with a block and 600 grit. You will see it is right next to the ejector slot. I then polished the whole bolt length with a block, moving the extractor side to side to reach the whole surface. I didn't try to remove the radial marks from the manufacturing process, just knocked off the tops of the ridges.
    IMG_5184.JPG
    I took a little time on the top and bottom surface of the lugs (not the back so headspace could not be changed) Again, not to remove the machining marks but just to smooth them out a little. You can see where I sanded by my thumbnail.
    IMG_5187.JPG
    I polished the cocking surface, shown by my fingernail.
    IMG_5192.JPG
    Lastly, I lifted the back of the extractor and slid some 600 paper under it and worked the extractor back and forth to polish the under side.
    IMG_5188.JPG
    All of that done, I washed the bolt down with paint thinner and re-assembled the bolt, oiling as I went along. The bolt is much smoother and I am really happy with a quick 1 hr job.I have read that I may need to polish the extractor hook because it helps the rounds slide under it. I will leave that until I have cycled quite a few rounds through the action. I am still considering whether I will tackle polishing inside the action and doing the rails so there may be an additional Stage 2 but I am concerned with getting grit in the trigger/safety/ejector mechanisms.
     
    Last edited by a moderator: Dec 13, 2018
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  2. Nhoro

    Nhoro AH Veteran

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    One thing I left out, The ejector slot needs polishing inside and deburring along the corners and edges. This makes a lot of difference as you first start the bolt moving forward.
     

  3. Shootist43

    Shootist43 AH ENABLER GOLD SUPPORTER AH Legend

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    Nhoro, concerning your aversion to using a "paste" of any kind , do you have access to Gun Scrubber? It is an aerosol that removes many kinds of "gunk" very quickly. I went the paste and Gun Scrubber route on my CZ without any of your mentioned undesirable effects.
     

  4. Rick Cox

    Rick Cox SILVER SUPPORTER AH Fanatic

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    Thanks so much for this post and the photos. I will try some of this, but honestly my 550 seems smooth. The magazine follower can be made to stick however (you have to work at it) so maybe I should start there.
     

  5. Ridgewalker

    Ridgewalker AH ENABLER LIFETIME BRONZE BENEFACTOR AH Ambassador

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    Very interesting, thanks!
    Just a thought, but in tool machining, I’ve used Dykem (painted on and let dry) on parts. Then assembled and operated them. Disassembled again and you could see the high points, interference points, and focus on polishing them down. Also have had to use a permanent marker when Dykem wasn’t quickly available.
     
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  6. Rick Cox

    Rick Cox SILVER SUPPORTER AH Fanatic

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    I like it.
     

  7. Dr Ray

    Dr Ray AH Legend

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    It amazes me that the rifle left the factory on this condition!
     
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  8. John J

    John J AH Veteran

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    Here was my take on buying a CZ. It was about 50/50 as I read and researched here in the CZ quality. I could get into a 416 Rigby for $1200. If it was good great if it needed some work, I'll save the money and get it done. But I got into it cheap just to try. Mine isnt the smoothest but not the worst. It feeds and ejects just fine. It could some love but it's not absolutely necessary. I like mine and one day it may go to AHR but not any time soon.
     
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  9. Nhoro

    Nhoro AH Veteran

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    Sure I could have used Wd 40 or carb cleaner. I was just concerned that I could really get into the action to clean without loads more work. I usually find that simple little jobs take days once you make a mistake and then have to fix it! Call me a nervous nelly. I was tempted to try your method but I preferred being able to see the problem and polish it away.
     
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  10. Nhoro

    Nhoro AH Veteran

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    I found the bluing on the bolt was exactly like dykem. Also the radial polish on the bolt shows the lengthwise high points. I have used a permanent marker in place of dykem too but I didn’t need it this time.
     
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  11. Nhoro

    Nhoro AH Veteran

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    Mine wasn’t bad at all and probably would have smoothed up with use. But my 1 hr with 600 grit has made a difference and pretty much for free.
     
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  12. Nhoro

    Nhoro AH Veteran

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    It wasn’t too bad but a little bit of work has made it better. I do agree that cz could do themselves a favor and polish those few surfaces. I am sure they would sell more rifles.
     
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  13. Nhoro

    Nhoro AH Veteran

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    Stage 2- i didn’t take any pics of this action polish because my wife was chasing me to get ready for a birthday party for my friend daughter. I also don’t think I would do it again. It didn’t make as much of a difference as the stage 1 polish. In summary, I removed the sear/cockinlinkage,the trigger assembly ,ejector and the safety/ bolt locking lever. I polished the ejector top surface and sides where I could see they rubbed. I polished the safety camming surface (this made the safety much quieter and easier to operate. I did the rails, upper and lower and the rounded part where the bolt rides with 320, just knocking off any rough bits. I also demurred the edges,back and front. Washed it all down with lacquer thinners,oiled and reassembled. The sear/ cocking piece spring was a headache to reinstall. It is smoother but not easy to reassemble so I would skip this unless you are pretty patient.
     

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