Matrix is Evike's way of labeling guns from Chinese manufacturers. They don't actually make or even rebrand anything. It's just Evike's labeling system.
It gets very confusing, I know...
That Kar98K is actually made by DBoys, and it a decent gun. Externals are great, but internals are a bit iffy. Accuracy is awful. Truly awful... I mean, it has a two piece INNER barrel... Whoever thought of that one should be shot. That combined with the reliance on very expensive shells make it a very very limited skirmish piece.
If you are looking for a short range plinker, or are a WW2 fanatic of sorts, it's a good choice, but if you are planning on doing a normal skirmish with it, make another choice.