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Thread: ZKK-600 7x57 Hard to chamber

  1. #31
    Member Marty Henry's Avatar
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    And although that's a control feed style extractor, the chamfered edge makes me believe it will also push feed so that's the best of both worlds.
    Micky Duck likes this.

  2. #32
    Member Micky Duck's Avatar
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    Correct THAT one will...his Bruno,maybe not.
    75/15/10 black powder matters

  3. #33
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    Quote Originally Posted by Billymavs View Post
    Because I paid a gunsmith to check it ? It’s only now that live factory ammunition has been introduced I’m finding problems.

    He wasn’t to know either, as I just asked for a spec check and visual inspection check over that it wasn't flogged out and cactus before shooting it.

    So far it owes me 450$, so it’s not the end of the world.
    450 dolleros? Jealous

  4. #34
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    Name:  IMG_5650.jpeg
Views: 119
Size:  1.58 MBName:  IMG_5652.jpeg
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Size:  2.09 MB

    after removing the bolt guts and giving them a coat of vivid, and feeding them In as advised this is what we have, S&B and the PPu both showing totally different contact points

    Currently have the chamber plugged and soaking with a third round bore solvent to be followed by 100% toluene to make sure any materiel that wasn’t showing up yesterday is removed weather it wants to come out or not

    If it persists after a Chem melting session and a thorough brass brush for chamber neck and throat respectively it will be off to a smith for further investigation

  5. #35
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    Quote Originally Posted by Billymavs View Post
    Because I paid a gunsmith to check it ? It’s only now that live factory ammunition has been introduced I’m finding problems.

    He wasn’t to know either, as I just asked for a spec check and visual inspection check over that it wasn't flogged out and cactus before shooting it.

    So far it owes me 450$, so it’s not the end of the world.
    Definitely do not give up on it yet. My bet is that a full length sized case will chamber perfectly and the problem you are having is the miss match between US specs (the gauge) and Continental (the ammo). A handloader is your best bet of sorting this out. Rounds that fit perfectly in my 6.5 T3 would not chamber cut to match the Redding FL die. There was an article about miss matches with the 7x57 in a recent Handloader or Rifle Mag.
    GPM.
    GPM.
    csmiffy likes this.

  6. #36
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    Quote Originally Posted by grandpamac View Post
    Definitely do not give up on it yet. My bet is that a full length sized case will chamber perfectly and the problem you are having is the miss match between US specs (the gauge) and Continental (the ammo). A handloader is your best bet of sorting this out. Rounds that fit perfectly in my 6.5 T3 would not chamber cut to match the Redding FL die. There was an article about miss matches with the 7x57 in a recent Handloader or Rifle Mag.
    GPM.
    GPM.
    As luck would have it there is a die set right under my nose, and late 70s early 80s so period correct for the rifle.

    I’d like to see if today I can get it improved, but I will pull apart some of those factory loads and resize the brass ect, and assuming you are on the money, it should be shooting in no time.

    A pain to be sure not being able to use factory ammo, but if it shoots as good as I’m lead to believe older ZKK series does it will be worth it

  7. #37
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    It doesnt look like the cases are "headspacing - are there any marks on the shoulder? Or are they all on the body of the case. Or am I not seeing it right. Cheers

  8. #38
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    If the issue is a spec between US made ammo (SAAMI spec) and Euro chamber (original chamber spec from the Mauser and people that invented the thing) you might have a solution in a "body" die for that caliber.

    A possibility is a Redding bushing style full length resizing die and taking the bushing and guts out (in effect a full length body die that doesn't change the neck, only the shoulder and body). It is possible to run live ammo into one of these, and bumping the shoulder and body back. This might give you enough clearance to be able to use US spec factory rounds with just a quick run through the press to marginally reshape them.

    The purests will scream here, but it is a known practice and it's OK if done with care.

  9. #39
    Member Marty Henry's Avatar
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    Well honestly I was expecting marks on the shoulder, they're not there. Your idea of pulling some factory rounds and running them through that due us a good one. I theory the die shouldn't touch them. If it does then we're well in the way to a fix. If it does work then out another case through blackened and see where it grabs.

  10. #40
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    I don't "buy" the mismatch theory, CIP (Euro) and SAMMI (US) specifically work to "harmonize" critical dimensions, and in any case PPU is Euro.

    Looking at the cases pictures I wonder if there is a lump of something on the chamber wall in the area of the case body. A Headspace guage is cut away in this area so might have chambered ok and told the GS that it was within spec. It wouldn't necessarily have highlighted a chamber anomaly.

  11. #41
    Member 7mm tragic's Avatar
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    Is there a chance that this rifle is a 7x57R? and would that present a head space issue?

  12. #42
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    Quote Originally Posted by Tentman View Post
    I don't "buy" the mismatch theory, CIP (Euro) and SAMMI (US) specifically work to "harmonize" critical dimensions, and in any case PPU is Euro.

    Looking at the cases pictures I wonder if there is a lump of something on the chamber wall in the area of the case body. A Headspace guage is cut away in this area so might have chambered ok and told the GS that it was within spec. It wouldn't necessarily have highlighted a chamber anomaly.

    After a blast through the solvents and brass brushes for the 6th time I can now pick up and feed just fine, but the bolt up/down to lock and unlock is still far to stiff, almost like the bullets to far forward if that makes sense ?

    I’m about to resize some factory ammo and see what that results in otherwise I’m thinking somethings askew with the neck/throat as there isn’t really anywhere else, I can see the chamber 100%and I’m confident where the “body” of the case is is 100% Spick and span but the neck obviously is a bit hard to get a really good look at without a bore scope handy

  13. #43
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    Quote Originally Posted by Tentman View Post
    I don't "buy" the mismatch theory, CIP (Euro) and SAMMI (US) specifically work to "harmonize" critical dimensions, and in any case PPU is Euro.

    Looking at the cases pictures I wonder if there is a lump of something on the chamber wall in the area of the case body. A Headspace guage is cut away in this area so might have chambered ok and told the GS that it was within spec. It wouldn't necessarily have highlighted a chamber anomaly.

    After a blast through the solvents and brass brushes for the 6th time I can now pick up and feed just fine, but the bolt up/down to lock and unlock is still far to stiff, almost like the bullets to far forward if that makes sense ?

    I’m about to resize some factory ammo and see what that results in otherwise I’m thinking somethings askew with the neck/throat as there isn’t really anywhere else, I can see the chamber 100%and I’m confident where the “body” of the case is is 100% Spick and span but the neck obviously is a bit hard to get a really good look at without a bore scope handy

  14. #44
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    Firstly, pulled a random PPU from the box, disassembled and gave it a resize in the older Lee die set and sent it through twice painted up with no projo

    1# Name:  IMG_5657.jpeg
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Size:  2.05 MB no contact
    2# Name:  IMG_5658.jpeg
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Size:  1.91 MB no contact

    Bolt is still extremely stiff on lock and unlock….

    Maybe I need to get in the locking lug and dig around with a pick ? The pressure has to be interference somewhere.

    Name:  IMG_5654.jpeg
Views: 144
Size:  1.16 MB shiny as a brass bell in there !
    Micky Duck likes this.

  15. #45
    Member Grey Kiwi's Avatar
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    My last BRNO (.270) was 45 years ago...so maybe memory is fading a bit...but in the photo of the bolt with case sitting in it, there seems to be a lot of space between the rear of the case and the bolt face. I can see a lot of space/shadow back there.
    Almost as though the extractor claw is clamped in nicely, but stopping the case from seating right back on the bolt face.
    Or is that just a camera angle giving a false impression?
    How about the bottom lug on the bolt...does the front action screw come up into the lug area and that screw too long (or stretched from years of being heaved tight) is jamming on the outer area of that bottom lug? That outer area is hidden by the extractor claw when you remove the bolt. Spin the claw out of the way and check the lug for gouges?

    Name:  IMG_20241212_151005.jpg
Views: 137
Size:  4.11 MB
    Last edited by Grey Kiwi; 12-12-2024 at 08:02 PM.
    Marty Henry and csmiffy like this.
    Artillery...landscape adjustment since 1300AD.

 

 

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