There is a bit more to it...
This is an endless repeat issue because there likely are several dozens similar threads, but you deserve an answer just as much as the last person who asked, so, to summarize the objective facts:
Both CZ 550 / ZKK 602 and Win 70 have:
- Controlled round feed (CRF). Whether it matters to you or not is your personal choice, there is no shortage of folks who do not care, and, truth be told, push feed (PF) rifles have just as good a track record as CRF. I personally like CRF not so much for extraction purposes (C clip extractors work), as I do for the fact that it is about impossible to inadvertently load a CRF (unless its extractor was butchered/beveled), as it is easy to push a cartridge in the chamber with a PF and leave it there unwittingly. I personally know people who witnessed someone being killed with a PF rifle after its feeding was discussed and group tested, and in the heat of the discussion and the rifle changing hands everyone forgot that a round had been pushed into the chamber... Of course, the rifle itself did not kill the person, stupid handling and a long list of inept gun safety violations did, but the bottom line is that CRF on that rifle would likely have prevented the accident...
The objective differentiating characteristics are, in no particular order:
- CZ 550 / ZKK 602 have drop belly large capacity magazine. This is the object of this thread, already commented on... I am not sure I always buy the 4 vs. 6 argument, as I do not chamber a round until I am about to shoot the rifle. In some cases it is possible to manually feed one round under the CRF extractor and get it carried into the chamber in addition to a full mag, and in many cases it is not timely to do so, therefore magazine capacity is what you have, and the discussion becomes 3 vs. 5. Everyone will have their own opinion. I personally would rather have 5 rounds than 3 in a DG bolt rifle...
- CZ 550 / ZKK 602 have 100% forged steel machined bottom metal. Some Win 70 have a steel bottom, some have a pot-metal cast bottom. Pot metal bottoms can break. I had one on a .340 Wby break under recoil just at the floor plate hinge...
- CZ 550 / ZKK 602 have double square bridges with integral scope bases. These will never shake loose. Win 70 have screwed on scope bases. Even if you re-drill and re-tap the holes and threads from 6x48 to 8x40 screws, the bases will always be an add-on. Admittedly on a .375 H&H it is not as big an issue as on a .416 or .458. I have seen several sets of bases come loose on .416 Taylor, .416 Hoffman and .458 Win rifles put together by premium rifle smiths... I have personally had bases shake loose on a .340 Wby after ~100 rounds...
- CZ 550 / ZKK 602 have appropriate barrel contour and weight. Win 70 do not. Yes some prefer their scoped .375 to weigh 9.5 lbs. Many prefer them to weigh 10.5 lbs. To each their own. Admittedly the .375 H&H does not have tremendous recoil. A heavier CZ 550 really comes into its own with .416 and .458. People keep saying "Weatherby eyebrow" to refer to scope bite scars, because I guess the .378 and .460 Wby provided their fair share of these, but light .416 Rem and .458 Win do to... (as well as .375 RUM and the like, for that matter).
- CZ 550 / ZKK 602 have a barrel boss integral rear sight base and a barrel-band front sight base. Win 70 have screwed-on rear base and front ramp. Again, this is less of an issue on a .375 H&H and more an issue for .416 and .458, but whatever is screwed on a heavy-recoil rifle is less permanently attached than what is integral of barrel-banded. I personally lost a screwed-on front sight on a .375 H&H Voere Titan...
- All CZ 550 / ZKK 602 parts are machined steel. Many Win 70 parts, certainly post New Haven, but even during the last decade of New Haven, are wax-cast pot metal parts. Win 70 safety switch for example are known to break.
And of course,
- CZ 550 / ZKK 602 have a .416 Rigby length action. Win 70 have a .375 H&H length action. This is an irrelevant point for a .375 H&H but very much of the essence for larger calibers that are not based on the .375 hull...
Conversely,
- Win 70 have a true bolt-mounted firing pin-blocking safety. CZ 550 / ZKK 602 have an action-mounted sear-blocking safety. In case of a hard fall, it is possible for the cocking piece to jump the sear and fire the rifle. Thankfully, a Win 70 type safety can be easily retrofitted to a CZ 550 / ZKK 602 for about $300. This, in my opinion, is a must...
Not to forget the endless debate,
- Win 70 have a reputation for being smooth. This is actually erroneous. They are loose. But this indeed results in fluid handling.
- CZ 550 have a justified reputation for being rough out of the factory. ZKK 602 not so much. Based on rifles I have personally handled, I suspect that communist era ZKK 602 had an additional manual deburring manufacturing step, which capitalist CZ 550 skipped in the name of cost savings. This likely was the biggest possible mistake CZ ever made, because it killed the rifle with many American customers would failed to realized that inside the rough was a true diamond... About 2 hours with a few miniature files and sand paper will make any CZ as smooth as any Win 70. Keep in mind that Rigby of London used CZ 550 actions to build their $xx,xxx rifles for the several decades from the 1950's to 2015 when the magnum Mauser actions were out of production. This was not by accident but by educated choice...
I would personally buy the ZKK 602, put a $300 Bell & Carlson kevlar and integral aluminum bedding block & pillars stock, and a $300 American Hunting Rifles (AHR) Win 70 type safety on it, and have a rock solid, war-horse Safari rifle. But many will prefer the Win 70 and it is a fine rifle too. My point is that a CZ 550 / ZKK 602 with Win 70 safety is everything a Win 70 is, plus a lot more than a Win 70 can never be (double square bridge bases, drop belly capacity, proper barrel contour, integral rear sight, barrel band front sight, 100% steel, etc.)