I'm lucky enough to have both. 4.5K to 5k PRS rounds through the 5-27 ZCO. 1k rounds through the 5-42 March. Optically, you'll need to have both scopes side by side to notice the advantages of the March. They are both great scopes, with excellent post purchase support, backed by Companies that care about their customers. Both are robust, and have checked out on a scope poi checker, and a tall target test.
At 25x the ZCO has 15.6 Mil fov
At 25x the March has 17.4 Mil fov
The March has writable turrets, that are translating, with no rev indicator. 10 Mil turrets have very positive clicks, and readable usable spacing. So simplistic and robustness advantage here.
The ZCO has a non translating elev turrent with a rev indicator. With 15mil spacing it is a touch tight IMHO. 10 Mil is better on spacing in terms of readibility on the clock. The lockable turret and rev indicator give it the boojie advantage here. Some might argue those features are but another "thing" to go wrong when traveling or adverse environments or on the clock. Your preference might vary.
The ZCO reaches peak boost at 27x. The March is just starting its initial flex on optical horsepower at 27x.
The 5-42 has what I'd term is a "pro eyebox" meaning if your fundamentals are there, gun (optic and rifle) is setup correctly and you can build a consistent shooting position, you won't notice the optical compromises necessary to get 5-42x and a big fov. If your fundys ain't tight, you don't have the gun setup right, than the ZCO does have a slightly more forgiving eye box.
I prefer the March everyday of the week. Target acquisition because of the greater FOV, image clarity and color correctness allow you to see slight sways and swings to the target, resolution allows you to actually be mentally able to drive down to the target, and draw a circle with a sharpie around where the last round ACTUALLY impacted in the plate after the paint is long gone.
The ZCO is a great scope. If the March wasn't available, the ZCO would be my pick.
If you get the March, you want to make sure it has the writable turrets and that new Rudge reticle.
PM if you want further info regarding first had experiences between the two.
