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Discussion Starter #1
Anyone else using an Eotech? need some advice for zeroing a new unit to my PS90.

Thanks, Gregg
 

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I am curious too. I will be trying one out finally this weekend, and if I like the PS90, I plan to buy one soon. Eventually, I want an EOTECH as well.
 

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Discussion Starter #3
Shot mine today, using a 552, and it's nice. Difficult to get a good cheek weld because of how high the Eotech sits on the carbine, but I dont want to add any more garbage to this thing, so it is how it is. Not to mention I'm used to isoceles with a short arm, and there isn't enough recoil impulse to make a difference.

Asking for help, because I'm not sure what distance this thing is supposed to be zeroed at. Seeing people post that they are zeroing for 50, and 100. In the guard and at work, we zero our M4's on a 300 meter sillouette @ 25 yards center of mass, but if the max effective range of a PS90 is 200, do I just calculate the distance for zeroing a 100 yards less and move in closer?

Appreciate some help.

Thanks, Gregg
 

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I zero my AR15s at 50 yd. Based on the trajectory of 5.7x28 in general, and the height over bore for the PS90 sights, zero it at 50 yd for the max effective range (~200m using SS195, ~150m using SS197). If you intend on doing all CQB work, you may want to zero it at a shorter distance.
 

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How long will it take to zero. The PS90 doesn't have traditional sights like an AR -0 that would be somewhat easy to at least start - set it on the front sight and go from there.

Its a bit harder with the PS90 to start...
 

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Since the windage and elevation adjustments aren't precise, it can take awhile. However most people found their sights to be dead-on at 50 yd right out of the box.

The stock sight is a POS. I'd rather have iron sights than try to use those reflex sights in a real world scenario. I've never seen USSS ERT use the black reticle sights (which are sold as "Secret Service" sights) on public domain photos; they always have an Aimpount mounted atop the USG rail. They most likely do not use the P90TR due to the lack of good iron sights, so they buy the normal P90 w/ the USG Rail and Aimpoint for maximum versatility.
 

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ideal zero for an Eotech

My sister spent many hours playing with a ballistics calculator and then nearly a thousand rounds working out the best zero range for our PS90s.
The main discovery is that sight height has a tremendous effect on the ideal zero. (The ideal zero being the zero that gives the least amount of vertical deviation between 0 and 200 yards).
I don't remember all her findings but the ideal zero for an Eotech on a halo tri-rail is 90 yards, and the ideal zero for a Trijicon Tripower on a halo tri-rail is 60 yards.
Using these zeroes the PS90 is basically dead on from about 55 to 200 + yards. The 'problem' is that your shots will hit several inches low at closer ranges. We solved this problem by using internal lasers for the close range zero. But if you never intend on shooting past 75 or 100 yards I would recommend a closer zero range.
Before my sister's research I tried zeroing at 25 yards, that was a huge mistake.
In summary. The best zero will depend on your sight height and preference, and , (unless you have modified the riser for lower optics mounting), will absolutely be somewhere between 50 and 100 yards. The higher the sight, the more distant the zero must be, if you want to have any long range accuracy.
I can't wait for the low mount carbines to come out! They will make things simpler.
 

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Based on the ballistics for SS195 and the sight height over the bore, the EOTech + Halo Tri-Rail should be zero'd at close to 50 yd for a "flat" minute of man trajectory out to 200m.

When zero'd at 50 yd using the stock reflex sight and SS195, I was shooting only about 1"-2" low at 25 yd, certainly within minute of man.
 

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Well, I got to shoot one this evening FINALLY. I wanted to try it before I paid that much money for one.

I liked it enough that when I came home, I ordered my top rail and side rails. Also got my mag fix to make it 50 rounds. Now, I'm just waiting for the next gun show to buy the gun itself :)

I plan to put an eotech on mine. But, I have no plans to shoot past 50 yards. I think I"ll zero it for 50. And, then set my green laser for maybe 25.

The guy who let me shoot his was also zeroing 2 M16s for the local SWAT team.

He suggested that after I mount the EOTECH - rest the barrel assembly on a chair or table, and then look down the bore and adjust the Eotech accordingly. Then, when I get to the range, I should at least be able to hit the paper. Then, I can do find adjustments as needed.
 

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metroplex said:
Based on the ballistics for SS195 and the sight height over the bore, the EOTech + Halo Tri-Rail should be zero'd at close to 50 yd for a "flat" minute of man trajectory out to 200m.
this isn't true.
I invite you to run the numbers for yourself
here is an online ballistics calculator

http://www.eskimo.com/~jbm/calculations/traj/traj.html


the sight height is 4.9 inches, BC is around 1.6, velocity 2575, 28 grains.

compare the points of impact at zero 50 yards and zero, lets say, 75 yards

a zero at 75 will be flatter than a zero @ 50 for a sight so high

Metroplex, I work with PS90s on a daily basis, these babies are my business. I wish you would trust me for once. You have disagreed with every post I have made!
 

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Eotech sighting adjustment

Here's what I did. I attached a laser on the side and use it in conjunction with my eotech. That way I can see how much I am adjusting the eotech sights. It works pretty good for me. I took it to a indoor range to do this so I know at which distance would be best for initial setup. I just wish there was a lower profile frame to get it closer to the barrel.
 

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Re: Eotech sighting adjustment

aeronaut said:
Here's what I did. I attached a laser on the side and use it in conjunction with my eotech. That way I can see how much I am adjusting the eotech sights. It works pretty good for me. I took it to a indoor range to do this so I know at which distance would be best for initial setup. I just wish there was a lower profile frame to get it closer to the barrel.
I think the bore height thing is overrated.

Since I posted my posts up above on this thread - I have my PS90 with an Eotech. I have it sighted in at 50 yards, and I have my laser sighted in at 7 yards (for household defense distances.

I can get 1/2 to 1 inch groups at 50 yards. And, at 25 yards, I get about the same results as I did with the stock scope - about 2" low at 25 yards.

I don't really see any big issues w/ having the scope/eotech up a bit higher. The gun is not a long range gun. I don't think the height over the bore is really an issue until U start crossing the 100 meter mark. And then, U really need magnified optics to go out past that with decent results.

As for the earlier comments about zeroing - I ended up buying a cheap laser bore sighter. It worked well enough to get me on the paper when I started at 50 yards, and I only had to make some minor adjustments after that.
 

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So because of the nasty wind, I was only able to zero at 25 yards today, which I set at ~2 inches low. Is this more or less equivalent to the 50 yard zero?
 

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It's probably damn close - U';ll have to make some minor adj later - but it's probably close enough if ya had to run outside with it now.
 

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The PS90 isn't a precision weapon anyhow. The American Rifleman did some accuracy tests and the PS90 wasn't exactly stellar, but will hit minute of man out to 100 yd without any problem.
 

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I zero'ed mine at 75 yards. I used a boresight laser to light the target up at 75 yards then I adjusted the Eotech dead on. After that, I fired a few rounds and checked the alignemnt. Because of the bullet trajectory, I was sighted in lower than the bullett impact. I reinseted the boresight laser, chjecled the alignment of the Eotech (Which was still dead on) and then readjusted the Eotech to center on the bullet strike. Easy as that, zeored in at 75 yards.

Took about 10 minutes to do it.

Of course, the bullet impact will be lower, right on, higher, right on, and lower based on the distance you are shooting. The nice thing about the Eotech is that it is adjustable on the fly so if you know the distance to the target (estimated) and if you know the trajectory of the round you are using ( that I why I use my own reloaded ammo only at this time), you can always adjust and hit the target dead on.
 

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metroplex said:
The PS90 isn't a precision weapon anyhow. The American Rifleman did some accuracy tests and the PS90 wasn't exactly stellar, but will hit minute of man out to 100 yd without any problem.
I can consistently get 1 inch groups at 100 yards with my PS90. I consider that precise. It's actually more accurate than my savage 10FP, a heavy barreled bolt gun.
 

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I can get good groups at 50 yards. 100 yards is too far for me to see with an Eotech. I CAN hit the silhouette - but not in any "groups" :oops:
 
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