... I have found people will tell you their gun is accurate even if it's complete rubbish.
...]
That depends on the definition of accurate. I expect an open sighted handgun to stay within an inch with five shots at 25 meters when shot from a good rest. Since the ten ring for the 25m ISSC target is 50 mm, almost two inches, any handgun capable of two inch accuracy at that distance can be considered plenty accurate and I have found few service sized handguns that cannot get a three inch group from a rest with the right ammo.
While the black bullseye of said ISSC target is almost eight inches in diameter, those that shoot off-hand at 25 meters will know that any deviation from the shooting basics will result in a miss of this rather large target area and when I am at the gun ranges here, I see few people even putting their B-27 targets out to 10 yards .
Nevertheless, I read many range reports of folks on the gun forums that can shoot two inch groups off-hand @ 25 all day long with a three inch .22 WMR revolver and I tremble at the thought and have nightmares about it, that they could come to one of the matches with a real target pistol and humiliate me.