So I was digging about.....

[Ray]

In the clutter of the raycave for something else when I find a red laser bore-sighter contraption that sticks to the barrel's muzzle with a powerful magnet. You center it best you can by eyeball then, according to the brief instructions, adjust the scope reticle to be above the laser dot (at 25 yds.) half the approximate distance of the reticle height from bore center.

Sounds easy enough but 25 yrs is too far to see the red dot in the sunshine. It shows plainly at night but then it (red dot) appears too large to be precise and is not exactly round (the proverbial cluster of grapes) and it is difficult to make-out non illuminated reticles.

Indoors at much closer distance than the recommend 25 yds. it is quite easy to make the projected dot and the gun's reticle precisely intersect. Does anyone have any suggestions such as perhaps, cross and dot dead-even at 30ft. or cross two inches over dot at 25 ft. ? etc., etc......

[JimT]

Sighting in the .30-30 Marlin I gave my son-in-law for his birthday, I used a laser sighting thingy that is shaped like a loaded 30-30 cartridge. You put it in the chamber and then adjust the scope to it. I set it so it intersected the red dot at 50 feet. On the Range it proved pretty close and adjusting it to 50 yards was not any problem.

Not sure that will help you but it's all I got!

IMG_1362.JPG

[GunnyMack]

I haven't used one but I know they are all just to get you on paper, that being said it would be an interesting project to test 1" high at X , 2"high at X as far as POA/POI.
I'm a fan of looking through the bore and adjusting crosshair then shooting a couple and then moving reticle to impacts. It's fast and easy but has its limits with actions ya cant see through.

[AJMD429]

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(the unrelated part of my reply…)

One of the best things when you are using a scope is to get one of the little cheap lasers that mounts either on the gun barrel, or with a 1 inch scope ring mounts to a scope.

Then, all you do is:

1. use your crosshairs to aim and shoot 1-3 shots at a dot target.
2. set your gun in a rest with the crosshairs aimed at the dot.
3. adjust the laser dot so it is now aimed at the bullet holes.
4. then adjust your crosshairs so they are on the laser dot.

What you are really doing - the essence of ‘sighting in’ - is simply shooting your gun, and then making the sights or crosshairs align with where the bullets impact. The problem is once you start moving crosshairs or sites, you lose your point of reference, and there’s not a practical way to mount a gun that steadily during the process. The laser in this case is just marking your aiming point precisely, enabling you to make your adjustments without worrying about if you bump the gun a little bit.

(the related part of my reply…)

There are two points where the line of sight is crossed by the bullet trajectory. We think of the gun as being “sighted in” at the second, farther point. The first, closer point is where the bullet ‘rises’ to meet the sight-line. THAT point is very dependent on how high the line of sight is above the bore axis. It also depends on the angle ‘up’ of the bore axis, which, in turn, depends on where you want the gun sighted in, meaning where that second cross-over between bullet trajectory and line of sight is.

If you have precise ballistic data for a given load, you can get an approximate idea of where the first crossover point is based on the bullet trajectory, the range you want to be sighted in at, and the height of sights above the bore. If not, having your first crossover point out 20 yards or more generally works well enough to keep you on paper out to 100 yards for your final sighting in. Making that crossover point too close will loft your bullet pretty high and it might not be on paper at 100 yards.

If you visualize a triangle with the top part, being your line of sight, going off horizontally to your right, the 90° down from the left end is the height of your sights, and the lower part popping up from the bottom of the left leg of the triangle out to the right tip as your trajectory, you can estimate that at say 25 yards, which is a typical first crossover. If your line of sight is say 2.5 inches above the bar, then you could make an estimate for closer sighting in with the laser you have (or this would apply to any other sighting method as well). Just look at the triangle you drew and if you want to know where you would want the bullet to be at 10 yards it would be 10/25ths out from the left end of your triangle, so the height would be 10/25ths of the way from your sight height of 2.5 to the crossover of zero, so would be 1.5 inches. In other words, if you wanted to approximate the same thing as setting the first crossover at 25 yards but it’s too hard to see the laser down at that range you could do it at 10 yards and set it at -1.5”. It’s going to be only an approximation but hopefully it would get you on paper and 100 yards or at least at 50 yards. The problem is that any error is multiplied so if you are for any reason off by a half an inch at 10 yards you’ll be off at least 5 inches in 100 yards.

If you can get a hold of a laser that mounts to the gun securely enough to withstand recoil, then, using the method in the first section above is a great way to sight in any gun with a minimal number of shots. I ballpark my first shot by looking through the barrel and I simply aim the laser so I can see it down the middle of the barrel. You can use a small dental mirror for guns that are difficult to access. Since I will be shooting off of a rest, if I’m pretty sure I didn’t pull a flyer, I will just shoot one shot, aiming with the scope crosshairs, then use the laser to mark where I need to move the crosshairs to and move them. Then I will fire one shot to assure that everything is correct, and I’m almost done with just two shots.

I’ll do that at 25 yards to 50 yards and then shoot a few shots at 100 or wherever to fine tune a zero just using the crosshairs. Depending on the cartridge and trajectory, I might sight in at 0” at 50 yards, or a couple inches low or high, depending on sight height, and on what I want the maximum “point blank” range to be.

As an aside (mostly applicable to folks using bottleneck high velocity cartridges for long range shooting), you get a deeper point blank range, if your sights are rather high above the bore axis. Depending on how you want to define your ‘point blank’ in terms of elevation tolerance (i.e. +/-2” vs +/-4” you may start at zero yards. Even if you want +/-2” and set your scope 4” above bore, that’s not generally a big deal. You still find where being 2” high gives you the 2” low that’s farthest out there, and it will be with pretty high sights. So go with a high but comfortable mount, then if you are 2” low at 250 yards and zero at 200 yards and 2” high at 125 yards and zero at 75 yards and 2” low at 40 yards your ‘point blank’ will be 40-250 yards with your 4” high scope axis. Using a lower 3” scope axis might give you some thing like 20 to 200 yards, and a 2” one maybe zero yards out to 175 yards, but why do that..? The type of firearms you are trying to reach out further with aren’t going to typically be guns you care too much about shooting at 20 yards. Plus, if you’re really want to shoot a squirrel in the head with a 243 Win at 10 yards, and your sight line is 4” high and you know you are 2” low at 40 yards, you know you are 4” low at the muzzle, so 10/40ths of the way between -4” and -2” is -3.5”; so aim 3.5” low if you really have to take s precise 10 yard shot with your long range rifle…! It is a lot easier to fudge a couple inches at 10 yards them to try to account for several inches of drop out past 200 yards, partly because you’re not likely to know the exact range out that far.

[Tycer]

Scope stuff
Mounting:
https://youtu.be/wgn6ejQzcL0?si=ckVw8dmEaTVkG4FC

Zeroing:
https://youtu.be/bN3UTvR0lP0?si=DOPpOcpJJqQkjNhp

[FLINT]

never heard of one with a magnet. I have one that has various diameter rubber plugs that screws into the lazer part which has a cone that sits into the muzzle and then you turn it to expand the rubber plug which snugs it into the barrel and theoretically centers the lazer/cone in the bore.

anyways, yes, as others have mentioned, the point is only to show you generally what direction your barrel is pointing so that you can adjust your sights/scope to get close to the lazer dot and that should save you a couple rounds at the range.

[Grizz]

and is not exactly round (the proverbial cluster of grapes) and it is difficult to make-out non illuminated reticles.

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cataract surgery fixes this.

I live around tidewater, the way I sight the gun is to place the action sans bolt, or the upper sans lower on a support, and bore sight a float in the water. then move the crosshairs or the sights or the green dot or the red dot to agree with the picture thru the barrel. easiest way that i know of. for the lcp green dot I just moved the dot to the fly on the wall in the fixed sight sight picture. I've used other methods, this one is the simplest for me.

[samsi]

and is not exactly round (the proverbial cluster of grapes) and it is difficult to make-out non illuminated reticles.

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cataract surgery fixes this.

Not always, I still have some astigmatism after surgery. It's usually not an issue but if I really focus on the dot it looks like a figure eight leaning over.

My experience with the laser bore sight is similar to others here, it will get you on paper, but there's still some work to be done.

[Grizz]

and is not exactly round (the proverbial cluster of grapes) and it is difficult to make-out non illuminated reticles.

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cataract surgery fixes this.

Not always, I still have some astigmatism after surgery. It's usually not an issue but if I really focus on the dot it looks like a figure eight leaning over.

My experience with the laser bore sight is similar to others here, it will get you on paper, but there's still some work to be done.

that's interesting. it sounds like there is some individual variations. would bore sighting work for you? it helped me out.

[jeepnik]

I have one of those barrel devices that has various arbors for everything from .22 to .45. They work great at shorter distances, and even at longer distances on days when the light isn't bright. Over the years it's save quite a bit of ammo. It beats the heck out of looing through a barrel, if that's even possible on the firearm.

[Ray]

I don't think my particular example is made anymore but this appears to be an improvement on the design....

https://www.grafs.com/retail/catalog/pr ... ctId/28623

The disadvantage is the difficulty of centering muzzle face on the flat magnet.

Thanks for the advice(s). I quite understand the concepts of bore sighting but only wondered dead-on dot or cross so much over dot at a more reasonable distance for dot visibility. Just cannot see it at 75 feet in the daytime.

The instructions for the bore laser that jim shockey endorses on the telly for verifying post airline handling scope regulation on hunting trips says dead-on dot at 25 feet but the photo examples show the dot some 1.5 inches below the cross on the grid that comes with the set.

Another disadvantage that I can imagine for the magnet mounted laser is if the muzzle is less than plumb/square then the laser is going to point wonky.