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