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View Full Version : Aimpoint M4 & Magpul Rear Sight


jamaicanj
02-24-11, 08:50
I have a bushmaster M4A3. The carry handle has been removed and replaced with an Aimpoint M4. I bought a magpul rear flip up sight and have not put it on as yet.

This morning in the coffee room my coworker tells me that the magpul rear sight height is off and I won't be able to cowitness the sights due to the relative heights of the magpul rear sight, aimpoint m4 with standard mount, and the bushmaster front sight.

Of course I'm at work and not happy to hear this, so I'm checking to see if anyone can chime in to confirm or correct my coworkers opinion.

Thanks

All the best
J
ASH556
02-24-11, 08:55
I have a bushmaster M4A3. The carry handle has been removed and replaced with an Aimpoint M4. I bought a magpul rear flip up sight and have not put it on as yet.

This morning in the coffee room my coworker tells me that the magpul rear sight height is off and I won't be able to cowitness the sights due to the relative heights of the magpul rear sight, aimpoint m4 with standard mount, and the bushmaster front sight.

Of course I'm at work and not happy to hear this, so I'm checking to see if anyone can chime in to confirm or correct my coworkers opinion.

Thanks

All the best
J

Pure BS! First, the Magpul sight height is fine. Second, the Aimpoint is parallax free, so no matter where the dot is in the Aimpoint tube, it still hits POA/POI. The one area where your co-worker may be close to correct is that the Bushmaster does not (at leas with standard construction) use an "F" front sight base, meaning that you may need a taller front sight post to zero the Magpul rear. In either case, the Aimpoint will not be affected.
Safetyhit
02-24-11, 09:05
Tell your co-worker he is a dummy.
Smuckatelli
02-24-11, 09:13
the Aimpoint is parallax free,

Technical question; how do they make it parallax free?

I have no experience with Aimpoint only the Unertyl scope that I used with the M-40 A1.
ASH556
02-24-11, 09:35
Technical question; how do they make it parallax free?

I have no experience with Aimpoint only the Unertyl scope that I used with the M-40 A1.

It has to do with the position of the led and the lens. See here: http://www.aimpoint.com/us/about-aimpoint/technology/
C-grunt
02-24-11, 10:23
Any sight in dificulty will be the result of the improper front sight base on the Bushmaster. You might need to get a taller front sight post.
cj5_dude
02-24-11, 10:30
To be truly honest, NO sight is actually 100% parallax free. There will always be a little shift, but the Aimpoint is mostly parallax free. And your buddy is full of crap.
jhs1969
02-24-11, 10:35
I have twice called BM to complain about the "short" front sight post that is almost unscrewed when zeroing. They sent me a free taller front sight post. This was several years back, I don't know if they would still do this or not but it might be worth a try.

Good luck
Safetyhit
02-24-11, 10:37
Folks he hasn't even installed the sight yet and will likely have no issues after doing so, at least as a result of an issue with the Magpul sight as stated. But if the Bushmaster post is that short on his weapon then I suppose it could be an issue, though I never experienced it with mine.
montrala
02-24-11, 10:44
To be truly honest, NO sight is actually 100% parallax free. There will always be a little shift, but the Aimpoint is mostly parallax free. And your buddy is full of crap.

I made little test. Installed Aimpoint CompM3, that I got for testing several years ago) into wise and aimed it at IDPA target (I was changing distanced between 10 and 100 meters). Then I looked trough it while changing my viewing angle in relation to sight tube. Dot stayed like welded to same spot on target until my viewing angle "moved" dot to about an edge of tube (almost to point where dot is about to disappear). At 100m this movement was equal to width of A zone of IDPA target.

I made same test to Eotech (some older model for 2 AA batteries) with less satisfactory results.

This un-scientific test made me choose Aimpoint as my favourite red-dot.
JimmyB62
02-24-11, 10:45
It has to do with the position of the led and the lens. See here: http://www.aimpoint.com/us/about-aimpoint/technology/

I didn't see anything there in reference to parallax. I also don't see how a non-magnified scope can even have a parallax issue. Care to explain?

I understand that no matter your viewing angle the red dot always stays on target, ie; POA=POI no matter the angle but I don't see that as parallex free.
JasonM
02-24-11, 10:56
I understand that no matter your viewing angle the red dot always stays on target, ie; POA=POI no matter the angle but I don't see that as parallex free.

That's the very definition of parallax-free... the dot will not move in relation to the target no matter what part of the tube you are looking through.

And OP- co witness shouldn't matter- zero the irons, and zero the red dot and then just shoot. You should not be lining up the rear iron, the red dot and the front sight.
ASH556
02-24-11, 11:16
I didn't see anything there in reference to parallax. I also don't see how a non-magnified scope can even have a parallax issue. Care to explain?

I understand that no matter your viewing angle the red dot always stays on target, ie; POA=POI no matter the angle but I don't see that as parallex free.

First you must understand the definition of parallax (most don't):
par·al·lax (pr-lks)
n.
An apparent change in the direction of an object, caused by a change in observational position that provides a new line of sight.

In layman's terms as it relates to optics: a false image of the reticle in relation to the target based upon the position of the shooter's eye in relation to the reticle. As shown in the link to Aimpoint's website, the positioning of the LED in conjunction with the dual lense design provides a (mostly) parallax free optic. Any curved lens will have some refraction at its extremities, but, the Aimpoint design mitigates this to almost a non-issue.
JimmyB62
02-24-11, 15:16
First you must understand the definition of parallax (most don't):
par·al·lax (pr-lks)
n.
An apparent change in the direction of an object, caused by a change in observational position that provides a new line of sight.

In layman's terms as it relates to optics: a false image of the reticle in relation to the target based upon the position of the shooter's eye in relation to the reticle. As shown in the link to Aimpoint's website, the positioning of the LED in conjunction with the dual lense design provides a (mostly) parallax free optic. Any curved lens will have some refraction at its extremities, but, the Aimpoint design mitigates this to almost a non-issue.


Maybe it was so obvious I didn't see it. Thanks for the explanation.