The ZKK series of rifles (600, 601 and 602) started production in 1966 and finished when the CZ rifles superseded them in the late 90's or early 2000's.
The ones with the pop-up peep sight in the receiver bridge means it was produced somewhere between 1966 and about 1976. After about 1976 they did away with the peep sight. The earlier rifles with the peep sight are more desirable from a collectors view point. The later produced rifles were not finished off as well either.
The ZKK rifles were available in 2 different stock shapes with cheek piece and forend tip etc, and a more classic shape with a fair bit of drop at the comb. The classic stocked rifles had the front sling swivel mounted on a band on the barrel which is regarded as better for a heavy recoiling rifle.
When new, each rifle came with 2 triggers......a normal curved standard type, and a straight set trigger you can use it just like a normal trigger but you also have the option to push it forward until it clicks which means it is "set" and will now go off with a very light touch. They were designed for the owner to be able to change them over when required.
The foresight blade can be changed for a lower or higher one by depressing the plunger button and sliding the blade forward.
The safety on a ZKK is forward on safe and back for fire(like cocking the hammer on a hammer gun) on the CZ it works the other way around.
I own 4 rifles on ZKK actions and they are great actions and rifles.
I would always choose the ZKK over the CZ and if it has the pop up peep site in the receiver even more so(three of the 4 I have have them).
