Bore sighting a red dot on a shotgun is easy since many shotguns have removable barrels or break-open actions that you can look through the barrel of. And getting an accurate bore sight is quite simple.
Most people will zero their shotgun at 25-50 yards. However, I suggest you bear in mind the kind of shooting/hunting you will be doing. If you are new to shotgun shooting, keep in mind that they do not have the range that rifles do, so research the effective range of the ammo you are using for the game you are hunting, which is usually found on the box.
What you will need to bore sight a shotgun without a bore sight tool.
- Shotgun with Red Dot Mounted - I am using a 1963 Remington® 1100 with a US Optics® RISE red dot sight and a WARNE shotgun rib red dot mount.
- A tool to adjust the windage and elevation of the red dot. Most red dots will come with one.
- I use a large box and paper plates. Round paper plates are cheaper than targets and easier to center in the bore of the shotgun.
- I also use a large cardboard box so I can see the pattern if I am way off.
- Something to hang the target, like a stapler.
- The shotgun shells you want to be zeroed for.
- Sandbags, gun vice, or another device to secure the shotgun barrel. I am using a Wiebag® cookie cutter as my main support bag.
- A portable table or something to set your shotgun barrel on to boresight it.
- Hearing and Eye Protection.
Bore sighting a shotgun without a boresight tool.
Ensure your shotgun is unloaded and pointed in a safe direction.
Set up a large box with a white paper plate in the center. Place the box at 25 yards with a safe backstop behind it; you can also place the target at a distance you want to zero, but if you put the target too far out due to the pellet droppage, you may hit too low to see the hit.
Assuming you have already mounted your red dot. Make sure your shotgun is unloaded and pointing in a safe direction.
Remove the barrel from the shotgun as per the manufacturer’s instructions. If you are using a break-open shotgun, open it.
Now, rest your barrel on your sandbags or rest with the muzzle pointed towards the target, centering the target in the center of a centered bore.
Then, without moving the barrel, look at where the dot is. As you can see in this photo, the dot is low and to the right.
Then, turn the dials on your red dot according to the manufacturer’s specifications until the dot is in the center of the target.
Then double-check to ensure that the barrel has not moved, that the target is still centered in a centered bore, and that the dot is centered on the center of the target. Now, you should be bore-sighted.
Reassemble your shotgun as per manufacturers instructions and see where it hits.
In this example, the shot was taken at 25 yards. Notice how close the highest concentration of pellets hit the center, which is the center of the point of impact. The shotgun is now bore-sighted and just needs a little adjustment to be zeroed.
How to zero a shotgun red dot.
After bore sighting, unless you already have it set up at the desired distance you want to zero at, you can put on a fresh target and move it to that distance. Take a shot and look for the center of the spot with the highest concentration of holes, which will be the center of impact. Adjust according to the directions for the red dot to match the point of impact to the point of aim.
Unlike zeroing a rifle, you're not going for a precision group; you want your spread to hit in the same area consistently. This can be verified by simply shooting your target a few times and seeing the pellets shoot out a bigger hole.
Keep in mind that your shotgun is zeroed for a certain distance, so your shot placement will vary for shorter and longer ranges. It’s a good idea to test both the drop and spread pattern at various distances with the kind of ammo and choke you will be using to know what the most effective point of aim will be.
Using a red dot, some hunters can learn to estimate target distances visually by judging the size of the target inside their red dot window.
