How long should you use a can of Triple Seven powder? I have had a can for several years now keeping it sealed tight in my gun safe (without a dehumidifier) but have been told that I should shoot it up or replace it by season's end. I have to admit, I haven't been able to get consistant groups with my Encore or even groups less than 3" or so and I'm wondering if new powder will cut my groups in half. I do plan to eventually switch to Black horn 209 but its tough to find in my area without driving over an hour. The cost isn't too appealing either.