I'm wishing to travel to the US and am currently in Canada on an eTA, if I travel south of the border for a few days would I be allowed entry back into Canada and if so would it reset the six months? I am not overly concerned if the timer does not reset but I do wish to know if I'd be allowed back in.
Canada does not have a specific rule about how long you have to wait between visits. The only fixed rule is about being admitted for a maximum of six months on a visitor visa.
However you are absolutely not allowed to use a visitor visa (or visa free entry) to live in Canada for long periods. The border officer has discretion over whether and how long to admit you for, but staying six months in Canada, then departing for a short while and seeking readmission is definitely going to be a problem. The most likely result is that you will not be readmitted when you try to return to Canada.
If you had an extremely good reason that you could support with documentation you might be readmitted for a short while - for example if you were flying home from a Canadian airport after your US trip, and just wanted to go straight to the airport and fly out. But you would probably be readmitted only long enough to go to the airport and fly out.