Honestly, I dont see it. Yes they are similar, extremely similar... but they are the same weapons, clearly modeled on real world weapons that are old and have not changed in some time. It is understandable to me. Even if they reused assets from another game, whats the big deal? They look fine to me.
Also, the only weapon shown in the screenshots you posted where you can make out any real detail is the garand, and there are definitely some differences in the texture, subtle yes, but they do not appear identical to me.