I never even considered it might be a threading problem, just assumed the whole SM P3 section below the base (including the threads) was too long. But after seeing your post, and that the P3 top cap threading doesn't go all the down, it very well could be. I remembered the large beveled section on the ProVape 510 adapter so grabbed a comparison shot of the two.
I'd have to disagree that the Provari is out of tolerance based on my picture above of the large beveled section at the bottom of the ProVape 510 adapter. ProVape made it this way, for whatever reason. SvoeMesto needs to conform to their specs.