Looking at your models, it's certainly not quality or price that's holding off buyers, I think that ratio is more than good.
I know that with my models it took some time for google to show them higher up in searches. However cgtrader does not show any tracking about from where people came to your product page, if it was on-page search, google, pinterest... so also for my models I don't know if that's relevant and it's hard to find out.
You could try and see if your titles, tags and descriptions contain actually searched keywords (you can try the free browser extension keywords everywhere). As an example: A search with keywords everywhere for "low poly gun" shows that it's googled by people approximately 250 times per month. For one of my models, the "main keyword" is searched for 70/mo, which converts to about 1 sale per month on cgtrader alone. Your sales seem to approximately match that conversion rate if we consider "low poly gun" as the term people will search for.
Maybe you just need more eyeballs on your product pages. Are you doing anything to promote your models? E.g. pinterest, any artist pages like behance/deviantart, twitter...
Another thing you could try - Have you thought about bundling up your weapons in a collection for a slightly lowered price? I think game asset packages usually sell better but I don't know if that applies to weapon packages.
Keep us updated how it goes!
