I check zero every year with every rifle I take out. Usually, I concentrate on 4 candidates and start bringing them out in August. Rifle Season starts in Mid-November, so that is plenty of time. I have 1 or 2 that are known performers and I leave 2 slots for new rigs and new loads. With the surgery this summer, I had to scale back my experimentation. I try to have 4 ready to go by the time Muzzleloader Season roles around in Mid-October.
With some rifles, I could put one round downrange, see that it's shooting to the same spot and put it away until season. I usually run 3-5 rounds through them just in case. I have a Ruger Hawkeye that is that way. The Mauser from Hell also seems to be fairly dependable in that regard, but it took years to get it that way.
Others? My Savage 99 takes used to take 5 shots minimum before it would settle down and I then I could find where it was shooting. Dyna Bore Coat reduced the problem considerably, but it still is a temperamental beast.
