That weapon is actually Daewoo K1A according to the pixiv tag, the receiver is AR18 style receiver than the MK18's AR15 style and there is a Korean lettering near the magazine release button if you look closely. The problem is there is no Daewoo K1A tag. So, should the mk 18 carbine tag be replace with daewoo_k1 tag or daewoo_k1a1 tag or make a new tag?