I recommend you put the bore sighter in a piece of tubing that simulates the bore to be closer to how it will actually be used. The telescoping tubing by K&M Metals that you see in hobby shops will work and let you select something close to your bore size.

I also recommend you bear in mind that most drill chucks don't center things perfectly. You would want your adjusted laser beam to wobble to the same degree and in the same direction as the chuck wobbles it for it to be accurate in a bore. I think a more precise method is to mount the sighter in the tubing, then turn the tubing on a Sinclair case runout gage base or in a couple of V-blocks by hand. Sit at one side of the room and bounce the laser off a mirror at the opposite wall to put the beam on a piece of paper or other target near you. That lengthens the light path, exaggerating any error so you can get a more precise adjustment. If you place the rotating block between two parallel larger mirrors, you can bounce the beam between them several times to get a really long light path for best adjustment sensitivity. Just watch out not to put the light in your eyes doing this.

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Nick

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Orange Hat Family Member
CMP Certified GSM Master Instructor
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"First contemplation of the problems of Interior Ballistics gives the impression that they should yield rather easily to relatively simple methods of analysis. Further study shows the subject to be of almost unbelievable complexity." Homer Powley

Even with all of this, it won't be perfect. I actually had to buy the cartridge type for my Barrett .50BMG because the plastic arbor on the end of me boresight wouldn't sit level in the rifling. One of the "feet" on it kept falling in between the lands and wouldn't allow it to sit straight. You probably wouldn't have that problem with the o-ring or magnetic type, but I don't know for sure.
The best thing to do is to remember that anything you can buy to boresight a rifle is not perfect and never will be, but it is better than not having one!

I bought a Bushnell and the light was so off center it would change significantly while spinning the sighter in the barrel. Then I bought a cartridge style, and it only worked one time before the battery was dead.

Waste of time and money.

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It's not rocket surgery, for crying outside!

Agree. I got a Bushnell unit a few years ago, and it was basically useless. Not precise enough @ 25 yard to get me on paper at 100. Tossed it and bought an optical unit. Life is better now.

Well, I just ordered one of the Bushnell things that sticks in the barrel, but I didn't order it to bore sight scopes because it's too simple to zero one in just a couple of shots. I ordered it simple to set my chronograph up. I'm tired of making a dozen trips back and fourth getting it positione right. I've tried the taking the bolt out, and eyeballing it, I've tried putting a small light in the chamber and sighting it from the chrony but still have to make several trips. Now I'm gonna try the laser bore sight and place a piece of paper in the shade holders and move it until the dot is where it needs to be.

Yep. That's the best way to set a chrono up. I've been recommending that for a couple of years now, and even acquired a cheapie second bore sighter on close-out that lives in my range box just for that purpose. If you're using a scoped rifle, especially, after getting the gun bagged so the scope stays on the target and then getting the laser right in the middle of the screen areas, it can surprise you how far up your scope line of sight appears to be in the screen area. That extra inch and a half shows. You can then better appreciate how some people shoot their chronographs accidentally.

BTW, I keep a yellow ECI (empty chamber indicator) in my kit that has the words "remove bore sighter" written on its flag with a Sharpie marker. I remove the bolt (not necessary, but having to pick up the bolt and put it in again makes me double-check everything) and I stick that into the action for chronograph setup. I decided to ad that step after looking at these photos.

__________________
Nick

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Orange Hat Family Member
CMP Certified GSM Master Instructor
NRA Certified Instructor
NRA Patron Member

"First contemplation of the problems of Interior Ballistics gives the impression that they should yield rather easily to relatively simple methods of analysis. Further study shows the subject to be of almost unbelievable complexity." Homer Powley

I got the Bushnell and it works great for setting up chrony.

Since I have it, may as well play with it. I have a my scope squaring setup outside. It's a platform and clamping system I built on the side of the night security light's eight inch diameter telephone pole, so it does not wiggle or move around. I have this pointed toward a storage building with a large roll-up door. The door has a perfectly level horizontal and vertical lines in a cross on it for scope leveling. I clamp and level a rifle in the setup on the pole, aimed at the cross on the door and square the recticle in the scope with the rifle.

I also use this setup when I swap scopes. I mount the rifle in it with the scope cross hairs centered on the cross on the door, swap the scopes out and adjust the scope I'm putting on so it's center the cross. I'm never more than a couple of clicks off when I test fire it.

I mounted a perfectly zero'd rifle in my pole device and centered the scope on the cross on the door. I stuck the bushnell laser in the rifle, and it was about four inches left and low. You can take it out of the barrel and reinsert it and it will change every time. I took it in a complete circle all the way around the center of the cross, but never got it in the center. You can not rotate in while it's insterted the barrel. The rifleing holds the adapter and all you are doing is screwing the screw tighter or looser. There is no way you can do anything with the unit that's repeatable so trying to adjust the centering screws in the front would probably only make it worse.

As is, it will always get you on the paper at 25 yards. It's more than simple enough to make you first shot at 25 yards and adjust the scope to about one inch above POI. Then move out to 100 yards make one more shot and adjust your scope again to POI. That will have you more than close enough to shoot a three shot group to adjust for zero then. Five shots and the scope is zero'd. Now, if you have one of those cheap scopes that every time you make one adjustment, the other one changes too, then you might want to make another three shot group to verify zero. I have a Leupold Rifleman that's that way, you can't just make one ajustment and think that's going to put you in the bull because every time you move one, the other changes POI also. I've learned that if I change if from 100 yard zero to two inches high for 200 yards I also dial in a 1/2" of right and visa versa when going back to 100 from 200.

Same experience as Jodum. They work great for me and save me lots of dough getting a new rig on paper.

I have used both. For me the lazer is quicker and less hassle. The bushnell log is good but constantly turning it to keep it straight is a pain. Helps alot if your not alone. Why shooters shoot them out, well I get excited to try out my rifle after sighting it in too. It's never happened to me ....yet. But when I was heading out to the gun range a while ago I was just up the road before I realized my pants were still at home. Who am I to judge. Just be carefull fellows, when a gun explodes, and that HAS happened to me, it's not pretty. later