https://apg-clan.org/vbdownloads.php?do=download&downloadid=228

This is my 2X scale crosshairs and some of Tim Hill's crosshairs that I removed the red colours, those are helpful for players with a High-Res screen and the default crosshairs are hard to focus. But use these crosshairs and aim better.

Simply unzip those .spr files in your C:\Program Files\Steam\steamapps\common\Half Life\gearbox\sprites\ folder and hey presto!