TBL004
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Anyone know the diameter of a 2 MOA RDS dot?
2 MOA RDS
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herrwalther
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Leupold Deltapoint is a 2.5MOA dot. Standard is 3 or 3.25 in most pistol optics that don't use multiple reticles.
https://www.leupold.com/shop/red-dots/series/deltapoint-pro
https://www.leupold.com/shop/red-dots/series/deltapoint-pro
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TBL004
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herrwalther thanks for the info and link.
Varminterror
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You’re asking the diameter of a 2MOA red dot…?
I feel like we’re missing some context, and the question isn’t the question.
I feel like we’re missing some context, and the question isn’t the question.
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TBL004
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Prior to getting and installing a RDS on an AR15 I was reading up on absolute co-witness and lower 1/3. Being new to AR's wanted the best possible sight alignment for both close and long distance shots. Absolute co-witness sighting would align the front sight just touching the lower portion of the red dot. If the AR front sight was wider than the diameter of the red dot in a quick mount shooting situation it would cover and block out the dot. Thought if a front post sight was as narrow or narrower than the diameter of the red dot it would eliminate that. After installing the RDS and using the lower 1/3 the concern is now nonexistent. That was the (newbie) premise of the original post. Definitely was over-thinking the process.
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Varminterror
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I may still be misinterpreting the question, but I’ll address some of this which might or might not answer the quandary:
First: A red dot sight is nothing more than a projector and a reflector screen. The laser dot is emitted from the back of the sight towards the screen (glass in the window), and the color selective reflective coating pushes the laser dot image back at our eye. Just like a front projector at a movie theatre projects images onto a screen, with the images bouncing back to the audience’s eyes.
If proper beam divergence is chosen, the dot will remain the same size to our eye regardless of where the sight is positioned - farther away, the window gets smaller in our FOV, but the dot remains the same apparent subtension because it has farther to diverge - so 2 MOA stays 2MOA whether it’s receiver mounted close to our eye or mounted on the barrel of a handgun and held much farther away.
This doesn’t add up. The red dot is closer to our eye than the front sight, so the post cannot block the dot. Wide posts do block the TARGET picture, wider than the dot, but the dot will always be visible since the sight post in absolute cowitness is positioned behind the dot.
Shooters do lose some refinement in sight picture with an absolute cowitness, because the bottom of the target is obscured, taking away a significant perimeter of the dot against the target picture. This can hurt precision, and can hurt how easily and how quickly the dot is picked up, but the dot remains in front.
Well… if memory serves, the front sight post in AR’s is relatively fine at .052” - 52 thousandths of an inch. In a 16” carbine with standard carbine gas system, that covers something on the order of 10 MOA. Alternatively, skiving sight post thickness down to 2moa would require a blade (not really a post) which is only 10 thousandths thick - about as thick as two and a half sheets of printer paper… how well can you see the edge of 2.5 sheets of paper at 18”? How easy will it be to center that skinny little blade in the rear aperture? How small would the new aperture need to be? How durable would that front sight be?
Eh, nah, we don’t do 2MOA front sight blades for a reason. But that’s why red dots have 2-8moa dots and scopes have .2-.3moa reticle lines - to allow more refined placement.
Yup - or a guy can slide their head slightly to misalign the dot from the sight post and have a free-floating dot in the open space.
Easy to do some times.
Personally, I’ve abandoned cowitnessing of fixed sights - and even folding BUIS’s. They just don’t bring value for my uses, and my red dots and scopes are plenty durable and reliable (I do replace my batteries regularly - why go all the way to “dead”)?
First: A red dot sight is nothing more than a projector and a reflector screen. The laser dot is emitted from the back of the sight towards the screen (glass in the window), and the color selective reflective coating pushes the laser dot image back at our eye. Just like a front projector at a movie theatre projects images onto a screen, with the images bouncing back to the audience’s eyes.
If proper beam divergence is chosen, the dot will remain the same size to our eye regardless of where the sight is positioned - farther away, the window gets smaller in our FOV, but the dot remains the same apparent subtension because it has farther to diverge - so 2 MOA stays 2MOA whether it’s receiver mounted close to our eye or mounted on the barrel of a handgun and held much farther away.
This doesn’t add up. The red dot is closer to our eye than the front sight, so the post cannot block the dot. Wide posts do block the TARGET picture, wider than the dot, but the dot will always be visible since the sight post in absolute cowitness is positioned behind the dot.
Shooters do lose some refinement in sight picture with an absolute cowitness, because the bottom of the target is obscured, taking away a significant perimeter of the dot against the target picture. This can hurt precision, and can hurt how easily and how quickly the dot is picked up, but the dot remains in front.
Well… if memory serves, the front sight post in AR’s is relatively fine at .052” - 52 thousandths of an inch. In a 16” carbine with standard carbine gas system, that covers something on the order of 10 MOA. Alternatively, skiving sight post thickness down to 2moa would require a blade (not really a post) which is only 10 thousandths thick - about as thick as two and a half sheets of printer paper… how well can you see the edge of 2.5 sheets of paper at 18”? How easy will it be to center that skinny little blade in the rear aperture? How small would the new aperture need to be? How durable would that front sight be?
Eh, nah, we don’t do 2MOA front sight blades for a reason. But that’s why red dots have 2-8moa dots and scopes have .2-.3moa reticle lines - to allow more refined placement.
Yup - or a guy can slide their head slightly to misalign the dot from the sight post and have a free-floating dot in the open space.
Easy to do some times.
Personally, I’ve abandoned cowitnessing of fixed sights - and even folding BUIS’s. They just don’t bring value for my uses, and my red dots and scopes are plenty durable and reliable (I do replace my batteries regularly - why go all the way to “dead”)?
The Glockodile
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Relative sizes with distance...
Roughly twice the values up there, without getting into some nitpicking.
Actual size of the illuminator, or "dot" itself?
Not really sure.
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