bore sighting a scoped rifle before sighting in
Posted: Wed Aug 31, 2011 1:18 am
This question comes up occasionally. There are a number of ways one might pre-adjust the telescopic or other optical sights on a weapon before going to the range, in order to conserve the amount of ammunition needed for the process. I recognize that there are many methods of doing this. The best one uses equipment for the task, but this may be too expensive for some (like me!). So, here's a description of how I do it. It may help you, or give you an idea about how another method will serve you better.
I have a >2 meter high wooden fence in my back yard. From my living room, it is about 10-15 meters to this fence, and there is a direct line of sight from the living room to the fence.
The first thing needed for my method is a distance with a direct line of sight to a specific point. Looking at the fence from my living room, there is a large wood knot in one of the boards that is easily visible though an optical sight.
I set up my Wife's ironing board in the living room and select some pillows to put on the ironing board. I push a crease in the pillows so that I can place the rifle in the crease in a way that it will stay put. This takes a bit of adjusting.
The rifle needs a clear bore for this process. For a bolt rifle, I remove the bolt. For my Ruger #1, I drop the breechblock. For my SKS and AK, I remove the action cover, bolt and carrier. The idea is to be able to see through the bore from the rear of the rifle.
Next, standing behind the rifle, I move it around until I can see the knot through the barrel. By moving the rifle on the pillows, I can get the rifle to stay put, so that I can see the knot hole through the bore without touching anything. Then, I look through the scope or optical sight to see if it is centered on the knot hole.
At about 10 meters, the bullet will be rising to the line of sight (remember, the scope is above the barrel's sight line), which is what you want. However, the exact distance here isn't critical.
By sighting through the barrel, you may feel that this isn't exact. However, sighting through the barrel is just like sighting though a peep sight, and relies on the eye's tendency to find the center of a hole instinctively.
This process takes a bit of fiddling around. Once you figure out how to set up your pillows in a way that allows the rifle to stay put without touching it, you are on your way. You will have to go back and forth between adjusting the scope and then realigning the bore to your point of aim several times, but after a bit, you'll only need a few such processes to get the scope pre-adjusted.
Put everything back together. Now, you have a choice to make: If you aren't confident in your adjustments, get a paper plate and staple it to a stick, and put a black circle with a felt tip pen on the plate. (You don't have to use a paper plate. Any piece of cardboard or stiff paper that's about 25 cm in diameter will work.)
If you are using the paper plate, when out at the range, pace off about 25 paces and put the stick in the ground. Go back and shoot the plate and note where the bullet strikes. At this range, the plate is about the same size as a target 4 times larger at 100 yards. So, if your shot is, say, 3 inches to the left, you will adjust your scope to move the point of impact 12 inches back to the right. The same principle applies to a shot that's too high or too low.
You shouldn't have any problem hitting a target after bore sighting by eye, if you've done it right, and one sighting shot should provide enough information for your next shot to print on paper at 100 yards. (I don't usually need to fire a shot at 25 yards with my method. However, one shot at 25 yards may save you several at 100 yards if you can't hit paper at the longer distance.)
Now, you should be able to hit paper at 100 yards, and you can adjust your scope accordingly. For most rifles, I usually use the old rule of sighting in at 3 inches high at 100 yards. But your rifle/cartridge/shooting situation may have different requirements.
After everything is adjusted, I prefer to shoot a 5 shot group to ensure everything is as it should be. Some people just use a 3 shot group for this.
Now you should be ready to go. If you have not used the rifle before, and especially you have a wood stock and there are varying weather conditions in your shooting area, you may wish to return to the range under different conditions (rainy, hot, cold, etc) and shoot another group to verify your adjustments. Some rifles are prone to wander when the weather changes the pressure the stock puts on the barrel/action.
I have a >2 meter high wooden fence in my back yard. From my living room, it is about 10-15 meters to this fence, and there is a direct line of sight from the living room to the fence.
The first thing needed for my method is a distance with a direct line of sight to a specific point. Looking at the fence from my living room, there is a large wood knot in one of the boards that is easily visible though an optical sight.
I set up my Wife's ironing board in the living room and select some pillows to put on the ironing board. I push a crease in the pillows so that I can place the rifle in the crease in a way that it will stay put. This takes a bit of adjusting.
The rifle needs a clear bore for this process. For a bolt rifle, I remove the bolt. For my Ruger #1, I drop the breechblock. For my SKS and AK, I remove the action cover, bolt and carrier. The idea is to be able to see through the bore from the rear of the rifle.
Next, standing behind the rifle, I move it around until I can see the knot through the barrel. By moving the rifle on the pillows, I can get the rifle to stay put, so that I can see the knot hole through the bore without touching anything. Then, I look through the scope or optical sight to see if it is centered on the knot hole.
At about 10 meters, the bullet will be rising to the line of sight (remember, the scope is above the barrel's sight line), which is what you want. However, the exact distance here isn't critical.
By sighting through the barrel, you may feel that this isn't exact. However, sighting through the barrel is just like sighting though a peep sight, and relies on the eye's tendency to find the center of a hole instinctively.
This process takes a bit of fiddling around. Once you figure out how to set up your pillows in a way that allows the rifle to stay put without touching it, you are on your way. You will have to go back and forth between adjusting the scope and then realigning the bore to your point of aim several times, but after a bit, you'll only need a few such processes to get the scope pre-adjusted.
Put everything back together. Now, you have a choice to make: If you aren't confident in your adjustments, get a paper plate and staple it to a stick, and put a black circle with a felt tip pen on the plate. (You don't have to use a paper plate. Any piece of cardboard or stiff paper that's about 25 cm in diameter will work.)
If you are using the paper plate, when out at the range, pace off about 25 paces and put the stick in the ground. Go back and shoot the plate and note where the bullet strikes. At this range, the plate is about the same size as a target 4 times larger at 100 yards. So, if your shot is, say, 3 inches to the left, you will adjust your scope to move the point of impact 12 inches back to the right. The same principle applies to a shot that's too high or too low.
You shouldn't have any problem hitting a target after bore sighting by eye, if you've done it right, and one sighting shot should provide enough information for your next shot to print on paper at 100 yards. (I don't usually need to fire a shot at 25 yards with my method. However, one shot at 25 yards may save you several at 100 yards if you can't hit paper at the longer distance.)
Now, you should be able to hit paper at 100 yards, and you can adjust your scope accordingly. For most rifles, I usually use the old rule of sighting in at 3 inches high at 100 yards. But your rifle/cartridge/shooting situation may have different requirements.
After everything is adjusted, I prefer to shoot a 5 shot group to ensure everything is as it should be. Some people just use a 3 shot group for this.
Now you should be ready to go. If you have not used the rifle before, and especially you have a wood stock and there are varying weather conditions in your shooting area, you may wish to return to the range under different conditions (rainy, hot, cold, etc) and shoot another group to verify your adjustments. Some rifles are prone to wander when the weather changes the pressure the stock puts on the barrel/action.
