@Gchef the author clearly doesn't know enough about guns. The damage output on the guns in the first chapter was ridiculous, as I commented there. He needs to summon an M. 2 Browning on a tripod with box magazine and plenty of ammo, screw the Skeletons with small 5,56mm rounds. If he's fighting monsters he needs heavy firepower or RPGs. A drum magazine grenade launcher is another idea. Shotgun, AR and hand guns aren't going to be effective unless its human targets.
Also having a dwarf "upgrade" your shotgun is retardedly stupid compared to just summoning higher calibre weapons.
I think this manga requires people to be ignorant about firearms though the Japanese generally seem that way due to lack of access and pacifist nature since their humiliating defeat and permanent occupation at the end of WW2.
@Baxkill must be sole serious magic fuckery going on for a skeletons light mass (just a pile of dried bones) to handle the recoil of an automatic rifle.
@Kaarme This "friend" seems more like a kid than an equal to him that could be a friend. She also acts whine and childlike. Therefore I kinda agree with Lolicon accusations because he can still be one low key without be obviously sexually interested.