Vladislav Evdokimov

I think it's possible. Krasnogorsk bayonet has 52mm flange distance and M42 is 45.46mm.
 

Here is someone selling (modified to M42) 50mm Vega lens which has same Krasnogorsk bayonet mount.

https://www.ebay.com/itm/MODIFIED-TO-M42-USSR-VEGA-9-f2-1-50-from-KRASNOGORSK-for-MIRRORLESS-CAMERAS-2-/173753581756

P.S. Ooops, just saw the date of your post...

The only reason why I choose k3 was because it can be found very cheap in russia and there are tons of them.
But yeah, the build quality is shitty. If I won't be dissapointed after first few rolls of film I'll definitely consider bolex or renting arri sr3 or 416. 

Thanks for support! I'm on the first floor so balcony is not an option = )

Got it, I'd better find another nos k3 body or stay with m42 for now.

Is hand processing an option with kodak/fuji ecn stocks? Just for test purposes.
Nearest film lab is in another city.

The flange distance is different 45.46mm on M42 and 52mm on Bayonet.
I've done the swap yesterday and just by looking through the viewfinder focusing seems okay.
But I know that the tolerance for the film plane is very small and I can't check that without shooting actual film...
 

As for loop moving Marc I think it's normal for k-3. 

Thanks for reply, that's sad.
I've disassebmled the front mechanism on mine completely, lubricated but it doesn't help either. My second K3 is new and works great, but it has m42 mount and I prefer bayonet for wide-angle lens (no planning super16).
Maybe it is possible to swap the front part completely in order to change lens mount between cameras?

I have the same problem with my K3, did you find a solution?