Home-made Laser Bore-sighter

[JMJ in NC]

Well, not really "home' made but... I had the machinist at work whip out an aluminum rod, with a bored-out center. I had a .174" gage-pin pressed into the back end. There are 2 sets of 3 adjuster threaded holes filled with #4-40 set screws. Inside is a basic cheap laser pointer. The 2 sets (fore/aft) of screws adjust the laser to point on center.

Adjustment is done by turning the laser while it's lasing at a wall. Keep adjusting until the point of light doesn't orbit. Next, do this again at a second distance.

I have a 7th threaded hole which holds a thumb-screw. Turn this and it presses on the power button of the laser-pointer and turns and holds it "on" for sighting.

The gage pin is a snug but not perfect fit to my barrel. Any "droop" of the laser will be in the same direction as the pellet trajectory. Gage pin size will depend on your particular gun barrel. One of my AG's needed a .177" pin, the other a .174" pin (corrected diameter per my next post). Each size will require a new laser holder assembly, unfortunately. Not ideal, but pretty decent.

Cost was pretty cheap - a few bucks for the gage pin, a few bucks for the laser pointer, a few more bucks for the set screws, and a favor owed to my machinist.

JMJ

[gene_sc]

Great idea John. Did you mean one is .177 and the other is .22?  When you gonna start selling them... Thanks for the great idea and sharing with us.

[a1Bogey]

Dang!!!! Another good, no Great,  idea to steal and use.   

Bogey

[Toolmaker]

Neat idea, but I worry that the gauge pin could damage the rifleing. Airgun barrels / rifleing are very soft and easy to damage.

[gene_sc]

Neat idea, but I worry that the gauge pin could damage the rifleing. Airgun barrels / rifleing are very soft and easy to damage.

Glad you caught that. I was on my first cup of coffee when I made my postback... Rifeling is very easy to damage as you say.

[JMJ in NC]

The gauge pin is a slip fit into the barrel. I'm not forcing it in - it's a running clearance fit with less than .0005" radial clearance.The next size gauge pin will not fit. I'd considered trying to fit machine a groove for an o-ring, but since the sighting-in will only happen about a dozen times in the life of the gun, I thought careful insertion of a pin would not be harmful. I made a slight chamfer on the tip of the gauge pin to reduce any chance of scraping.

Off-the-shelf laser boresighters use an expandible plastic bushing at the tip, and a cone at the muzzle/crown interface. They are also very hard to find in .177" caliber, and generally start at about $40.

I mistyped my original post. My Walther Force 1000 required a .174" gauge pin, whereas my Crosman Powermaster 66 fit a .177" pin.

No plans to sell any - sorry, but with a basic lathe and access to gauge pins, they are fairly easy to design and fabricate.

JMJ

[DMikeM]

Make the pin just a little smaller then cover with shrink wrap tubing