If this is a authentic Paradigm Modz Magma... contact the maker/vendor. If a clone... well, low price frequently means low expectations. Were it mine, I'd use it on another, cheaper
mod... rather than damage a Provari.
Be that as it may... the first suggestion is the most obvious. Buy a
510/510 adapter/extender. With this installed tightly to the atty, at least when you snug it to the Provari, you're not slowly doing damage to the (far more valuable) Provari threads. Looks like crap yes... but it would work.
The atomizer's electrical contacts are the 510 positive pin - with the M7X0.5mm threaded, male 'collar' acting as the negative, or ground. Any sort of 'clearance filler' product you might use to 'tighten' the thread fit between atomizer and battery should be electrically conductive... but not hard enough to damage the threads, male or female.
With that in mind, one product that is relatively soft - as in softer than the threads of both atty and mod - has high electrical conductivity as well as easy to apply and re-apply as needed... would be
adhesive copper foil tape. I've used it to obtain an electrical pathway on materials (carbon/kevlar) that would not otherwise support one.
Each wrapped layer of (0.07mm thick) tape would add a pre-distorted increase in thickness of 0.14mm to your atomizer... reducing male/female thread clearance (in effect, 'tightening' the fit), while maintaining a good level of conductivity. Apply as required.