Post '64 M70 triggers manufactured in New Haven can usually be tuned and have the weight of pull lightened very easily and without any filing or stoning. It's pretty easy to get a 3-3.5 lb. pull with minimal if any creep or overtravel. It's one of the reasons I really liked the Post '64 M70 and I did that modification immediately to the four or five I own. For a medium to big game rifle used in the field, I don't care to lighten them more than that.
Bruce