This is a George A. Wilson Match .45 ACP. It is one of three hand built by George Wilson, who was a designer for High Standard and a competitive bullseye pistol shooter. He designed this pistol for his own competition use in 1959, patenting the design in 1961.
Please see a full video takedown and review on ForgottonWeapons.com for a lot more detail on this pistol.
Image from lifesizepotato: https://thefiringline.com/forums/showthread.php?t=563661
The Delta AR Top Gun is an Italian made pistol built by hand during the mid to late 1990s. It is estimated that only around 200 were ever produced. It weighs 43oz and was offered in double stack .45 ACP (10 rds), 9x19mm (16 rds) and .40 S&W (12 rds). The Delta AR Tog Gun is a roller-locked short recoil, very much like the CZ 52 with a SAO trigger and firing pin safety.
There isn’t a lot of information available on these pistols beyond the occasional owner review, unfortunately. We did stumble across an owner’s manual in English, however: Delta Top Gun Manual [pdf].