How To Sight in a Laser?

[GJM]

I think it depends on what you are trying to accomplish. If you are using your laser primarily at close distances and have a small offset between laser and bore, the zero is less important. Using a laser like the X400, with a substantial offset, the zero becomes quite important.

I tried to figure this out when I was trying to pick a usable zero for an X400, and frankly having a heck of a time. Consider the following chart, showing a 7 yard zero for the X400:



At the muzzle, your bullet will have a 2.9 inch difference between POA and POI. At 7 yards, POA and POI coincide. At 20 yards, POA and POI diverge by six inches, making a difference in POI of 8.9 inches between the muzzle and 20 yards. At 35 yards, there is a full 17 inch difference in POI between there and the muzzle. The bullet will strike 14 inches below your laser dot. It is easy to figure out why I was having such a hard time.

Now consider the parallel zero:



From the muzzle to 25 yards, the POA and POI stay a consistent 3 inch offset, and then it diminishes until POA and POI are coincident at 50 yards.

With the 7 yard zero and an X400, I just don't have enough brain power to have a clue what POA and POI will be through 25 yards, no less 50 yards.

You can construct the same analysis for a laser with less offset like the CT laser grips. With those, and a parallel zero I just remember the bullet will strike one inch high and left for a long way. I try to make a final zero check at 50 yards with a laser, and going out at dusk it is easy to do this. It is amazing how small groups you can shoot at 50 yards in dim light with the laser on a pistol, and shooting 8 inch steel in those lighting conditions is faster than red dot or irons in any light -- bright or dim.

Spending a lot of time outdoors, frequently in dim or dark conditions, I am very keen on a usable 50 yard zero. Others who don't do that, will value this less.

[ToddG]

Very good point regarding which laser. I also think in terms of the CTC because it's the only laser I use. For that, a 50' zero (which I believe is what the company recommends) gives me very close to "zero" offset -- or at least no meaningful offset -- from 5yd out to as far as I'm likely to use it for any practical purpose.

[GJM]

Very good point regarding which laser. I also think in terms of the CTC because it's the only laser I use. For that, a 50' zero (which I believe is what the company recommends) gives me very close to "zero" offset -- or at least no meaningful offset -- from 5yd out to as far as I'm likely to use it for any practical purpose.

For a quick wag, take the offset of the X400 table and divide the 3 inch offset of the X400 by 3 to reflect the reduced offset of the CT laser grips. I wish I had the software handy to redo it with a different zero, such as 50 feet, but this came from a long ago project, and it was hard to find software to easily do the calculation.

[ToddG]

That's still assuming a 7yd zero whereas I do about a 17yd zero.

[Chance]

I wish I had the software handy to redo it with a different zero, such as 50 feet, but this came from a long ago project, and it was hard to find software to easily do the calculation.

Cool table! If you can point me to the equations you used, I might could reproduce at some point, although that'd be a while from now. I have MATLAB, Excel, and plenty of gp-language stuff lying around, although I don't know much about ballistics at transonic speeds, if your average handgun round even travels far enough for that to become an issue. I suppose I should break out my copy of Litz's book that's figuratively been collecting dust on my Kindle.

[Corlissimo]

With my C5L I did something very similar to what Todd did in post #10.

My pistols are for defensive use only (except for when I practice/train) and I figured that in a true DGU scenario I might not even have the time to turn the laser on, but when I do, and I need it, it will likely be at a distance greater than 10 feet but less than 100 feet.

Along with that, if I really needed a true precision shot I'm likely not going to use the laser at all and instead rely on my sights. I view the laser as a supplement most useful for out of position, awkward shots or to aid my old eyes in getting hits on a moving target inside the ranges outlined above.

As far as my actual zeroing process goes, I used a laser cartridge to get bore POI at my desired range then put the green dot on that red one. All that remained was actual live fire to verify my settings with my ammo choices.

[BN]

I sighted in the CT LG-417 laser on my Glock 17 at 50 feet. Then did a walk back using the center of a 9 inch paper plate covering the down zero of an IDPA target as my aiming point. I shot 5 or 6 shots at 6 feet, 12 feet, 50 feet, 25 yards, and 35 yards. All of the shots were in a 5 1/4 inch group centered on the paper plate. At 45 yards the dot was too faint to use. Close enough for me.