by shaman » Tue Feb 02, 2010 9:42 am
Be careful with a scope and sighting in at 25 yards as a way to get you on the paper at 100 yards. Remember the scope is set higher than the barrel. That parallax may mean that if you zero at 25 yards and then try to hit a 100 yard target, you'll be a foot or two off the paper shooting high.
Once you know that, you CAN use a 25 yard zero. A 25 yard zero can give you an idea of where you are regarding windage. For elevation, it's quite a bit different. For one thing, a 25 yard zero is a better tool working backwards. That is, if you have the rifle zeroed for 100 or 200 yards, you can go back and see where it shoots at 25 yards and then let that be a rough guide going forward.
Let's say you have a scoped rifle that's coming out of the case after a plane ride. You are at camp and can't get a 100 test shot off before dark. Before you left, you zeroed in at 200 yards, checked at 100 yards and knew you were 1" high and then checked at 25 yards and found that you were 1.5 inches low. Now, when you take that 25 yard shot at camp, you can verify both windage and (rough guess) elevation. You at least know if the scope was knocked way off during the trip.
Another way to do this is with the bore sighter. After you get sighted in, slip the bore sighter in and record the exact deviation on the grid. Store that on a slip of paper in the lens cap of the rifle. When you get to where you're going, check the deviation again with the bore sighter, and adjust it back to where it was when you left.