The first question I would ask you is 'how much do you want to spend'?. As a starter for the HW100 I'd personally look on the customstock website
customstock.co.uk.
These are all exceptional value for money and are probably suitable for most uses. I would recommend the CS700 and CS800 which look particularly good on a HW100. If you are -or become-a serious competitive shooter then others might be better but be warned they will be a LOT more expensive.
'It may be that your sole purpose in life is to serve as a warning to others'.