LA-5/PEQ-5 zeroing

[kawika]

I used the search feature. My whole team is stumped and so are some other bravos I asked in other companys. I'm not a bravo but bear with me.

Ok so the SOPMOD zero target states that the desired point of impact at 25M using a PEQ-5 is 16m up and 16mm right. The point of aim is center. To me this makes zero sense. If it was opposite I could see that. If the point of impact was center mass and the point of aim using the LA-5 laser was up and to the right(the location of the laser mounted on the top rail) that would make perfect sense.

Is the SOPMOD trying to get a 25 meter CQB zero? Even a POI/POA method wouldn't make sense using this target. If you take 16mm up and 16mm right at 25 meters for the bullet impact and take that same target out to 300 meters that would put the POI nowhere on the sillhoute anymore. The line of barrel and LA-5 crossing(which is does using the SOPMOD target) at 25 meters means that that is the last time it does so. Once those two paths cross they will only further and further seperate. The ballistics don't magically force the round to curve back onto the target at 300 meters.

Are we missing something or is the SOPMOD target supposed to say POA 16mm up and right and POI center mass? Ideally a parallel zero is what I want and to me that only makes sense reversing what the SOPMOD target says.

[The Reaper]

Originally Posted by kawika

I used the search feature. My whole team is stumped and so are some other bravos I asked in other companys. I'm not a bravo but bear with me.

Ok so the SOPMOD zero target states that the desired point of impact at 25M using a PEQ-5 is 16m up and 16mm right. The point of aim is center. To me this makes zero sense. If it was opposite I could see that. If the point of impact was center mass and the point of aim using the LA-5 laser was up and to the right(the location of the laser mounted on the top rail) that would make perfect sense.

Is the SOPMOD trying to get a 25 meter CQB zero? Even a POI/POA method wouldn't make sense using this target. If you take 16mm up and 16mm right at 25 meters for the bullet impact and take that same target out to 300 meters that would put the POI nowhere on the sillhoute anymore. The line of barrel and LA-5 crossing(which is does using the SOPMOD target) at 25 meters means that that is the last time it does so. Once those two paths cross they will only further and further seperate. The ballistics don't magically force the round to curve back onto the target at 300 meters.

Are we missing something or is the SOPMOD target supposed to say POA 16mm up and right and POI center mass? Ideally a parallel zero is what I want and to me that only makes sense reversing what the SOPMOD target says.

k:

Not sure I fully under the question, but essentially, bullets don't travel in a straight line.

The reason you can use a 25 meter target for a 250 meter zero is that the bullet goes up and crosses the sight line, then comes back down and crosses it again further downrange.

The horizontal offset on the target is to allow for the fact that the laser is offset laterally from the bore, as well as vertically. In that case, you get to choose the point where the laser and the path of the bullet converge, and I would assume that 16mm puts it on the point of convergence at a desired range. If you want them to converge at 300m., then do the math. Just be aware that prior to that (and afterwards by an increasing amount), the point of impact will be slightly off the laser spot.

HTH.

TR

[kawika]

Thanks for the fast response.
What is still not clear to me is why the horizontal offset is to the right for the point of impact with the point of aim being center mass. What you are describing is the point of aim/point of impact method of zeroing which I beileve the SOPMOD target is trying to achieve. However I don't see how putting the point of impact horizontally to the right at 25m, gets you a 300m zero. Or 100, 200 etc.

The top rail mounted LA-5 has the IR illuminator slightly to the right of the bore line. If you place this illuminator center mass and have your bullet impacts up and to the right at 25 meters, I don't see how that translates to hitting anything but targets up and to the right of whatever you are aiming at.

If I wanted to use the parallel method, I could see how placing the IR illuminator up and to the right with the impacts being down and to the left makes sense. It makes sense to me because this is the correct relation between the LA-5 and the bore line.

It doesn't say anywhere in the SOPMOD literature why it's 16mm up and right for POI. It does state that the CQB battlesight, or POA/POI method is not the prefered. It leans towards a parallel zero, which to me, the target is not achieving.

[mark46th]

Reading both these posts gave me an eye-ache....

[head]

The problem is that the laser travels in a straight line and is starting from offset right (if on the top rail). That means for the laser to intersect the bullet at 300m, you need your rounds to impact up and left of the laser on a 25m zero. (ETA: this may be your issue - my manual says the offset is up and left as opposed to your statement of up and right) Here is a rough sketch of why (note that I just depicted horizontal offset and if the zero target was designed to have impacts in the center for ease of viewing).

[head]

I think figured out your problem... are you using an LA-5 or a PEQ-5??? A "PEQ-5" is a visibile laser only that emits from the left of bore (if top mounted). I could be wrong, I had to google what a PEQ-5 is as I've only used PEQ-2, PEQ-15 and LA-5s. However, there are two SOPMOD zero targets, one that has the "up and right offset" like you described for the PEQ-5 Visible Laser and then a newer one for the LA-5 with a "up and left" offset like I drew. So, make sure you are using the right target.

[kawika]

awesome, that is definately what the problem was. we were using the SOPMOD target from our SOMPE computers, which as yah know have decently old files on them. thanks.