In resident evil 2 a Heckler & Koch VP70 (HK VP70) in resident evil 4 it wasnt a real gun but was based on others, which ones? I dont know.
I believe the one used in RE4 is based off of a Heckler & Koch Mk.23 mod.0 US SOCOM pistol. They look somewhat identical. Although it is also stated that Leon's gun in RE4 which is named the Silver Ghost was loosely based off of a H&K USP