I maybe vilified for this ... but here goes
The Russian Spartan I think is the least pricey of the three you mention it's made by Baikal.
I believe it will need the most work to smooth out (very stiff and rough)
Adco, They are just now coming in and I've handled one it was Ok ,but it too will need a bit of work (stiff to open).
I did not shoot it or shuck shells though. The concern here is getting spare parts.
You mention the Hammers spacing , both the Spartan and the Adco are wider than the....
TTn ( this was my choice ) Hammers are about 5/8" apart and easy to thumb a cock at the same time.
I have to say Walt Johnson of TTn was very helpful.
Out of the box I was very please with the fit and finish. The American Black walnut stock is beautifully figured, I particularly like the rounded pistol grip.
Both chambers were polished I had to do nothing to shuck shell.
A spare (lighter) spring comes with the gun and mine was fitted with a larger front bead sight ( than OEM )
The thumb lever is a bit stiff but smooth and the gun breaks open with little effort out of the box.
I will however, do a bit of touchup polish at the hinge.
I suppose It sounds like a testimonial, I'm just saying I'm very pleased with mine.
BTW ....I had Stoeger which needed the chambers polished and the ejector deburred before Shells would shuck. Also needed the hinge stoned so it would drop open without sticking.