Red Dot For Ranging?

[toby63 1,236]

am sure si pittawy did a vid on youtube using a laser to help rangefind

[Alsone 789]

am sure si pittawy did a vid on youtube using a laser to help rangefind

 

You can use a laser to range find, but it's as in my post #7 on the previous page.

 

What you're doing is mounting the laser higher than the scope so the laser is on a slightly downward angle which you adjust until the downward angle co-insides with the cross hairs at the chosen zero range. From then on by estimating the distance the dot is above or below the cross hairs, you have an estimate of the range provided you've taken the time to also calculate by trigonometry or practical testing the distance above or below at a range of different ranges.It is only an estimation though and one far less accurate than using a range finder as you're reliant on your eye to estimate the amount above or below the target at range. eg if you calculate at 200yds the dot will appear 6 inches below the target, then to estimate 200yds, you first have to visually estimate that the dot is 6 inches below the target when viewing it an unknown range! It's not easy to judge over long ranges, but the accuracy of your range estimation depends on your ability to precisely to judge the amount the spot is above or below the target.

 

Also, to be clear, the position of the spot in no way represents the aiming point apart from at the zero distance, as the laser travels straight and bullet travels in an arc.

 

Prior to the zero, the laser always appears above if top mounted and after the zero always below. The bullet on the other hand flies in an arc and passes both above and below by varying amounts. So the laser is only good for distance estimation not as an aiming point.

 

It's probably worth saying that over very short distances eg with an air rifle zero'ed at say 30 yds, the amount of difference at say 35yds or 25yds maybe so negligible that you can use the dot as an aiming point especially if you know if the pellet will be over or under.

Edited December 29, 2015 by Alsone

[Alsone 789]

I don't know if this helps or confuses, but this is my understanding / representation between laser, gun sight and bullet:

 

Edited December 29, 2015 by Alsone

[toxo 160]

The bullet path is irrelevant Alsone. We are only concerned with whether the target is closer or farther than our zero. I think I've got it worked out in my head. Wherever you point the rifle the dot will point AT the crosshairs. I say AT because if the crosshairs are pointing at a lesser distance than the zero the dot won't actually get to the crosshairs and will show as being above the centerline. If aiming at a point further than zero the dot will be going through the zero point to hit the ground at what seems to be below the centerline.

I've got a headache now

[Metalman2 45]

Borrowed from another forum, admittedly for air rifle, but this chap knows his onions, and at 70 yds or les, on a high mag it is fairly accurate

 

 

1. Join Date Aug 2007 Location Wakefield Posts 2,764 Post Thanks / Like

   RodN - that's a laser not a red dot. The dot may well be red but the red dot in question is referring to a reflex sight. Totally different things. A laser is best when several inches above the scope when it can then be used as a rangefinder and will be accurate to 2 yds out to 55 yds or more. Your laser is just not high enough to be any use. Play around in Chairgun with different heights and zeros and you'll find the laser beam can be made to follow the arc of the pellet for many yards after it starts falling away from the scopes zero.
   

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[Alsone 789]

The bullet path is irrelevant Alsone. We are only concerned with whether the target is closer or farther than our zero. I think I've got it worked out in my head. Wherever you point the rifle the dot will point AT the crosshairs. I say AT because if the crosshairs are pointing at a lesser distance than the zero the dot won't actually get to the crosshairs and will show as being above the centerline. If aiming at a point further than zero the dot will be going through the zero point to hit the ground at what seems to be below the centerline.

I've got a headache now

 

Wherever you point the rifle the dot will point at the cross hairs ONLY if the distance is the zero distance. You're quite right that if its shorter than the zero the dot will be above and further the dot will be below. Not going to repeat it all again as put it in 2 posts above, but to work out the distance, it requires you to estimate the amount above / below by eye and have pre-worked out the distance that the drop / elevation corresponds to in advance.

 

Yep gives a headache if you think for too long!

 

Yep works better at short distance.

Edited December 29, 2015 by Alsone

[Deker 3,478]

I don't know if this helps or confuses, but this is my understanding / representation between laser, gun sight and bullet:

 

 

In an example like this the laser and crosshair will be on zero at one point (assuming they had been set that way). If the laser and scope were mounted at the same height they would always read the same at every distance. Your scope and laser use light, and everything is straight (in principle), its only your bullet that is screwed by gravity.

 

I'm not easy with this method of range finding anyway, and I'd say it is fraught with problems, for instance, open flat areas, how will you ever see the dot, dense woodland and the dot may be blocked by other things on the way, full moon, etc. Without doubt range finding at night is harder than day, but practice, and or using a night serviceable range finder would be my suggestion.

 

ATB!

 

Edited January 5, 2016 by Deker