Need help in finding out the name of a novel I read; it came out after 2010. There are two novels released.
The hero's house is the site of a portal to a magical fantasy land and the villain comes from there to Earth to get modern tech to fight in their fantasy world. But the hero is taken back to that world during a confrontation at his house.
There he battles against a magical beast and defeats it with a gun as the bullets are copper jacketed which is anti-magic so could penetrate the magic shield of the beast but its extremely rare and expensive in that world.
There he reinvents gunpowder, railways, telegraph, etc to fight against the villains and he also learns magic as well. The villain uses chemical weapons etc in response.One of the sides uses hot air balloons as well.
In the second novel he comes back to earth and brings sniper rifles and other things to fight the wizards.