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GK
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Reged: 29/10/09
Posts: 161
Loc: Adelaide
Question on BRNO ZKK 600 details
      #169817 - 18/10/10 08:57 PM

I got lucky yesterday a made a deal on a 1974 ZKK 600 in 7x57mm. Unfortunately, I won't have it in my hands until after Christmas.

Its in very good/excellent condition but as always its missing its peep and it has the dodgy set trigger. Luckily I have these ready to go.

I was hoping someone might have a picture of an unmolested one so I can check a few things. In particular:

1) Is it supposed to have rubber recoil pad?

2) Do they normally have a sight hood?

3) It has the sling swivel mounts in the wood and barrel band but not the actual sling swivels. Any idea on what fits?

4)The wood looks like its quite dark (stained)? Is this original?

There is also a small chance that I might get its big brother in the future. Its a ZKK 600 that been rebored to 358 NM. To me this is perfect as normally the 358 NM is chambered in the much bigger and heavier ZKK 602.

George

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CHAPUISARMES
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Re: Question on BRNO ZKK 600 details [Re: GK]
      #169818 - 18/10/10 09:05 PM

Hi George,

You wouldn't have a rear express sight for a 602 in your "Kitty" would you ??

Cheers,

Jeff Gray

.

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GK
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Re: Question on BRNO ZKK 600 details [Re: CHAPUISARMES]
      #169823 - 18/10/10 10:01 PM

Unfortunately I don't Jeff, but I'll keep an eye out.

I thought you had a chance of one in Canada?

George

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TilleyMan
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Re: Question on BRNO ZKK 600 details [Re: GK]
      #169861 - 19/10/10 12:36 PM

Hi George

That 7x57mm sounds like a good find

Now to answer your questions (this is a summary of info posted on another web forum, for benefit of NitroExpress members)

ZKK 600/601/602 pics from original 1970's ZB brochure... note the ZKK600 has a late model cheekpiece stock, skip-line checkering, contrasting fore-end with a barrel band sling. Not what the Australian market was supplied with







1) Yes, they were fitted with a reddish ventilated recoil pad with the ZB logo moulded in, later changed to a black pad in the same design around the middle 1980's. They often perished into a sticky goo... worth bargaining $50 off the price.
The stocks were originally finished in quite a dark reddish brown nitrocellulose lacquer finish, and the stain seemed to be in the finish vs the wood. Certainly comes off easily with a bit of Selley's paint stripper (wrap in Gladwrap to accelerate the process).

2) Yes, a windowed hood was included with a curved base that fitted into the matching curved recess on the front sight ramp. Unfortunately the hood was not provided with a robust retainer pin and was usually lost on the first hunting trip. Because of the unique curved base, a 'normal' hood won't fit on... but once you know what they look like you can scan the ice cream containers up the back of gunshows. VERY occasionally one will turn up mixed up in all sorts of unrelated crap. I got my last one for $2

3) Depending on year of manufacture, ZKK's had either a non-detachable Euro style swivel mounted on a barrel band OR a non-detachable Euro style swivel mounted in the stock. I'd say someone added the fore-end mounted one to provide a QD sling.

I would be VERY reluctant to fire a ZKK 600 converted to such a large belted case as a .358NM... I've seen some eye-popping examples of 'gunsmithing' in my travels, but just because it may fit the action doesn't make it a good idea!

It may fire perfectly well in the smaller 600 action for 20, 50 or 100 shots and then let go without warning

ZB engineers were some of the best in the firearms business, and there would be a very good reason why they chambered the .358NM in the significantly larger 602 action. Safety factors and the elastic limits of ordnance steel would be one...

Sorry, I just can't give you an assurance that the conversion would be safe... the back thrust on the bolt face/front lugs vs the hoop strength of the remaining enlarged chamber walls + safety factor would have to be calculated... and I have no idea of the original steel specification or post machining heat treatment..

The facts remain... ZB engineers originally would have completed all these calculations and decided to chamber the .358NM in the ZKK602, NOT the ZKK600.

And I think there's something in that for all of us

Edited by CptCurl (21/10/10 10:38 AM)

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GK
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Reged: 29/10/09
Posts: 161
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Re: Question on BRNO ZKK 600 details [Re: TilleyMan]
      #169864 - 19/10/10 01:45 PM

Thanks TM,
Posting here for "completeness" made sense to me as well.

I think my stock looks like the one in the ZKK 601 add, however I think it has the ventilated pad of the others. I'll have to wait until I see it, but as I said, I believe the stock to be in its original finish. Also, I think that the fixed sling swivel loops have been removed in order to have some QD ones fitted to the original sling swivel points.

You have convinced me to steer clear of the 358NM chambered ZKK 600, but I still want to now what the issue is, ie not enough meat in the chamber shoulder area etc. Was the 358NM loaded to much higher pressures when factory ammo was round?

George

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TilleyMan
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Reged: 23/08/05
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Re: Question on BRNO ZKK 600 details [Re: GK]
      #169874 - 19/10/10 08:03 PM

Generally the issue is not just based on pressure... usually revolves around the thickness of the enlarged chamber walls vs the threaded area of barrel stub (stress risers), the amount of metal that needs to be removed from the feed ramp (also the lower locking lug reinforcement!) vs the backthrust to the boltface, the rebored barrel thickness at the muzzle and the working pressure of the new cartridge vs the old one.


.270 Win


.358 Norma Mag

Bit hard to get proper pressure data on the .358NM but the CIP PMax for the .270W is 4300 bar (62366 psi) vs the .358 NM of 4400 bar (63816 psi).
In this case they are actually quite close... however one real-life test reported a standard factory .358NM load at 63,900 psi... quite hot for a working pressure!

Recoil of a .358NM in the lighter ZKK600 would also be an issue vs the heavier 602.

BTW here's some shots of the ZKK front sight hood, apologies on the quality, it was taken with a 2MP camera camera phone... I miss my Canon A95



Edited by CptCurl (21/10/10 10:39 AM)

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kuduae
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Reged: 13/01/10
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Re: Question on BRNO ZKK 600 details [Re: TilleyMan]
      #169901 - 20/10/10 05:12 AM

Hi TilleyMan,
there are some errors or misconceptions in your above posts:
According to the 1991 German/CIP proof tables, the .308 Norma Magnum's maximum allowable working/service pressure was 3800 bar, same as for the 8x68 or the various Weatherby numbers. FI the .300 Win Mag and 7mm RemMag were given at 3700bar.
The Brno ZKK rifles were, for many years, the lowest-priced fullbore repeaters listed in the Waffen Frankonia mail order catalog, so they are quite common here. At least since the 1969 catalog Frankonia offered both the straight-comb "standard" stock without cheekpiece and other frills, and the so-called "export" or "luxus" Weatherby-style stock at some Mark60.- more, with MonteCarlo comb, triangular foreend, scip-line checkering, painted-on "rosewood" slanted foreend tip and inlaid white-line spacer. This abominable stock was only available at first on 600 and 601 actions. For a time in the 60s there even was a "Germanic" hump-backed stock with cheekpiece.
The 601, 600 and 602 receivers differ only in length! The barrel shanks, receiver rings and locking lugs are of the same dimensions, so all three are of the same strength and will take the same pressures. There were other reasons why they chambered belted cartridges in the long 602 actions only: 600 bolt faces were regularly machined to take standard 30-06 size rims, so these would need opening up to taake belted numbers. 602 bolts were already set up for belted bases, so it was probably easier to simply screw "magnum" barrels into these instead of making another type of 600 bolt. Further the 600 magazine would take only four cartridges, even after replacing the sheet-metal box, while the 602 mag easily gobbles up 5-6 belted cartridges. So I see no reason not to rechamber a 30-06 600 to .308NM, but there is more work involved: You have to open-up the bolt face, alter the extractor and, to make the thing feed properly, have to make a new magazine box. Zkk mag boxes usually have pressed-in guide ribs in front of the case shoulder. these will be in the wrong place after rechambering, cut capacity even further and impair proper feeding. After all that work you will end up with a rather light .308 Norma Magnum rifle, but that is a matter of personal taste and recoil tolerance.
Stock finish: The Brno people apparently did not grade walnut before machining. So you come across stocks with a lot of figuring like black streaks and fiddleback, and on the other hand very plain ones. There was no difference in pricing, but the plain stocks were usually finished or stained dark, while they left the figured ones more in their natural colour.

--------------------
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TilleyMan
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Re: Question on BRNO ZKK 600 details [Re: kuduae]
      #169905 - 20/10/10 06:30 AM

Kudae

Thanks for the additional information... very useful, as always

We seemed to get a mix of stock configurations here in Australia... but generally received the Monte Carlo "rosewood" tipped ones, which as you say are rather garish! Agree on the timber grading, some ZKK's exhibit striking fiddleback while others are plain and soft as Balsa wood

While I've handled a few ZKK 602's I don't currently own one (just 600/601's) so didn't have one on hand to compare. I was basing my reply on seeing some ex-mil M98's that have been Bubba-converted to .375 H&H etc... we don't have a gunsmith trade course here in Australia (though I believe it was once offered...) and skills vary hugely, hence my caution.

Given that new info, the rebarrelling should be OK... someone has gone to a LOT of work if it feeds and ejects well! Be good to know who the original gunsmith was...

BTW George originally posted it had been converted to a .358 Norma Magnum, not the smaller .308 NM, so I still reckon the original .270 Win barrel profile would be pretty thin at the muzzle if rebored to .358!

Cheers

TM

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kuduae
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Re: Question on BRNO ZKK 600 details [Re: TilleyMan]
      #169907 - 20/10/10 07:15 AM

Quote:

BTW George originally posted it had been converted to a .358 Norma Magnum, not the smaller .308 NM, so I still reckon the original .270 Win barrel profile would be pretty thin at the muzzle if rebored to .358!



Don't worry! Like most European rifle factories, Brno used the same outside barrel profile on all their production rifles of a given model, regardless of caliber. This eases production, as the same stocks, sling swivel rings and frontsight bases may be used on all. So a ZKK 600 in 9.3x62 has the same outside dimensions as the same model in .270. Result: The .270 with it's smaller bore is heavier than a 9.3x62! This is especially marked in the 602, when a .300 WinMag came nearly a pound heavier than the same model in .458 Win Mag! FI on my 602 in .458 the barrel wall thickness at the muzzle is only about 2.6mm.

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GK
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Re: Question on BRNO ZKK 600 details [Re: kuduae]
      #174394 - 29/01/11 05:55 PM

Here's a few pics of a BRNO ZKK-600 I finally picked up last week. Its in 7x57mm and was made in 1974. It appears to be in very good condition (esp. the bore which looks perfect). It needs to have the trigger guard and floor plate re-blued (as it was cold blued and has mainly rubbed off) and the stock needs some cosmetics. It did not have its peep sight but I have removed the one I found for the 601 and installed it. Compared to my ZKK-601 that was built in the 77, this one is incredibly smooth and better finished.

Cant wait to shoot this one once its appropriately scoped. I need to sort out some mounts as the ones I planned on using will be too high with this stock. Anyone know if the talleys that are made for the CZ550 fit?

George







Edited by CptCurl (13/02/11 11:51 PM)

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FATBOY404
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Re: Question on BRNO ZKK 600 details [Re: GK]
      #174396 - 29/01/11 06:36 PM

Very nice GK.It looks in good buckle.
The mounts are the same for the CZ's and the ZKK's.Just don't do the back one up too tight as it compresses the peep assembly.

I would love a 7x57 in the Brno's.I am trying to get a Brno model 21 in 7x57 out of a mate of mine but no luck yet.It has the spoon bolt handle,different cocking piece and twin set triggers.

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GK
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Re: Question on BRNO ZKK 600 details [Re: FATBOY404]
      #174397 - 29/01/11 08:01 PM

Thanks Neale,
Truth be known, I did not really have plans to get a 7x57mm but as soon as I saw it I jumped on it as the price was very reasonable. Only problem is this and another Greek MS that was picked up at the same time have depleted my stock money for the 9x57. These things happen.

I've been looking at some older posts and I noticed that you have Warne QD's for your BRNO's. Do these feature a recoil stop (for the cut-out in the LHS of the rear bridge)?

I too have a friend that has a ZG 47 that I hope to convince him to sell one day.

George

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FATBOY404
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Re: Question on BRNO ZKK 600 details [Re: GK]
      #174402 - 29/01/11 09:36 PM

Yes they do mate (the cut out).
I have four Brno's and four sets of Warne mounts.
I dont have any trouble with them at all and if I were to buy another scope it would go in the Warne mounts as well.
I like useing my open sights a lot so my scope goes on and off quite often and I never worry checking the zero as they have never let me down.

Cheers Neale.

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"WHATEVER BLOWS YOUR HAIR BACK"

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Homer
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Reged: 07/04/09
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Re: Question on BRNO ZKK 600 details [Re: FATBOY404]
      #174634 - 01/02/11 09:05 PM

G'Day Fella's,

I could probably go and Google this Question but it probably wouldn't be as informative as you lot!
So, here it is
How long after the Iron Curtain fell/failed was it before Brno/CZ firearms again got back to producing the real quality that they have been known for?

I can remember handling post Iron Curtain Brno/CZ ceterfire rifles, that appeared to have had their manufacturing details and serial numbers stamped on by some computer controlled "Center Punch" like device.
If I remember correctly, I have seen this same marking process, on Smith & Wesson handguns as well?

Thank you for your input into this question.

Doh!
Homer

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CHAPUISARMES
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Re: Question on BRNO ZKK 600 details [Re: Homer]
      #174643 - 01/02/11 10:22 PM

Hi Gk,

You know that you can get the Warne mounts no trouble as Fatboy404 has said but I got the Talley Mounts for the Brno 602 I bought and on the bottom of the box it says.: 30mm CZ550 Detach.W/Levers, Part Number.: 30CZL550 and is on the Talley website and yes they do send them to Australia.

Cheers,

Jeff Gray

.

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FATBOY404
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Re: Question on BRNO ZKK 600 details [Re: CHAPUISARMES]
      #174661 - 02/02/11 05:36 AM

I couldn't believe my luck as Warne make QD mounts for my 1957 mod 2 Brno 22,so I grabbed a set.
At $150 they are dear but it fits in with my plan of open sights,scopes and QD mounts.

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