Hello
SRvet, welcome to the madhouse
The Sauer 90 is a beautiful rifle and the smoothness of its mechanism is without equal. I know, I owned a gorgeous Sauer 90 Luxus in 7 mm Rem Mag for 20 years and loved it. I ended up selling it to a American collector who wanted it more than I did...
I expect that most answers that will come in this thread will question whether the Sauer 90 mechanism is TOO perfect for Africa. This is an argument that has been going for quite a while regarding 1970's era Steyr-Mannlicher, Sauer 90, Mauser 66, or such tight tolerances rifles for Africa. Some will argue that these actions tolerances are too tight to be sand-proof in Africa. Again, I know, I also own a Mauser 66 in .458 Lott that is so precise and glass-smooth that its action cycles itself when I tilt the rifle upward then downward after lifting the bolt... What it would do after a sand bath is likely debatable
The ZKK 602 / CZ 550 is taking the other approach. It is the AK47 of dangerous game rifles. Many complain that it is too rough,
which is true but easily fixable (keep in mind that Rigby themselves used this action to build their rifles for decades when the magnum length Mauser action was out of production). Paradoxically, it is also a very tight action from the factory. Rifle smiths who specialize in it (Wayne at American Hunting Rifles, Harlan & Meagan at Triple River Gunsmithing, etc.) "release" the action to make it comparable to the Win 70 which is actually not very smooth but very loose, and therefore cycles easily from the factory.
There are also the matters that;
- The ZKK / CZ has built in scope bases in its double square bridges. These will never get loose as the Sauer (and others) screwed-on bases can, and likely will, if you shoot one in Dangerous game (DG) or high recoil caliber enough. I shot loose the bases on a Mark V .340 Wby over the course of a few months pre-safari practice and a 12 days Safari...
- The ZKK / CZ has an integral rear sight island and barrel band front sight - and these sights are actually regulated from the factory. These too will never get loose as the Sauer (and others) screwed-on iron sights can. That is if there are any iron sights on the Sauer to begin with. I actually lost the screwed-on front sight on a Voere Titan .375 H&H...
- The Sauer 90 has a detachable - therefore 'loosable' - magazine of medium capacity (3). The ZKK / CZ has an integral high capacity (5) magazine. I do not really care so much about the additional 2 rounds, but enough spare magazines have been sold by Sauer, Steyr-Mannlicher, etc. to indicate that some are lost in the field...
- The Sauer 90 is quite light for a DG caliber rifle (7.7 lbs). The ZKK / CZ has a much more realistic - for DG calibers - weight of 9.4 lbs. By the time you take a quick shot under pressure in an uncertain field position with a very powerful light rifle, you may join the very populous "Scope Eyebrow" club...
- The CZ / ZKK is a true "Mauser" control round feed (CRF) action. The Sauer 90 is a push feed action. Each will decide for themselves how important this is to them. I personally am not overly concerned with the extraction argument, as much as I am with the security aspect: it is impossible to unwittingly leave a round pushed in the chamber of a CRF rifle, as it is possible to do so with a push feed rifle, and this HAS contributed (along inept rifle handling) to lethal accidents to happen...
When all is said and done, I suspect that the ZKK / CZ is a more traditional, and likely a more rational choice for Africa. I am not entirely sure how real the sand-proof argument is (unless you plan to be tossed by a buffalo and then somehow retrieve your rifle from under its hooves and finally kill it - this has happen often enough for the classic literature to be full of examples of it!), but the scope bases, iron sights, magazine, weight, CRF arguments are factual.
I hope this helps