2 MOA RDS

TBL004 · December 28, 2021, 08:30 PM

Anyone know the diameter of a 2 MOA RDS dot? TIA

cslinger · December 28, 2021, 09:14 PM

The “sight”??? All sights are different. You will need to be specific. (Aimpoint, Trijicon, Vortex etc. etc. )

If you are taking about the dot, 2 MOA is approx 2 inches at 100 yards. This might help as far as dot size at ranges

https://cmore.com/DotSize

Shadow9mm · December 28, 2021, 10:32 PM

are you talking about the actual diameter of the dot itself inside the optic? or how big it appears on the target?

actual dot size, no idea.

1 MOA is roughly equivalent to 1in at 100yds, 2in at 200 yds, 3in at 300yds. Thus a 2moa dot would be 1in at 50yds 2in at 100, 4in at 200, 6in at 300 and so on.

TBL004 · December 28, 2021, 11:05 PM

Was interested in the diameter of the red dot on a Holosun HS403R. Believe it has a 20mm objective lens. Thanks

zoomie · December 29, 2021, 01:49 AM

https://holosun.com/index/product/detail/id/132.html

"2 MOA Dot Reticle"

Double everything below:

If for some reason you're actually asking the diameter of the dot, here's a faux scientific guess.

Assuming the dot is meant to be viewed 6" from your eyeball, the dot is about 0.00349".

TBL004 · December 29, 2021, 10:16 AM

Thanks everyone for the replies and info. Appreciate it!

**JohnKSa** · December 30, 2021, 03:29 PM

A quick way to determine the size of 1 MOA, in inches, at a given distance is to divide the distance in yards by 95.5

For example, at 25 yards, 1 MOA is 25 yards / 95.5, which is about 0.26". To find the value of 2 MOA at that distance, just multiply the 1 MOA value by 2. That means 2 MOA at 25 yards is about 0.26" x 2, or about 0.52"

Another quick example.

At 238 yards, the value of 1 MOA is 238 / 95.5, or about 2.5" If you wanted to know how much 5 MOA is at that distance is, you would multiply that value by 5. So 5 MOA at 238 yards is 2.5" x 5. About 12.5".

cslinger · December 30, 2021, 03:54 PM

I did not know this. Thanks.

....The more you know.

**Unclenick** · December 30, 2021, 05:05 PM

The exact value is actually pretty easy to find, too, if your smartphone calculator has pi. Just remember that at 300 yards a moa is subtended by exactly pi inches. Thus, you just divide your range in yards by 300 and multiply the result by pi to get exact inches. For example, suppose your range finder tells you your target is at 750 yards:

750/300 = 2.5 and
2.5×pi = 7.85398 inches per moa.

Jim Watson · December 30, 2021, 08:48 PM

A lot easier just to take a minute of angle as an inch per hundred yards.
At 1000 yards, an IPHY is 10", a geometric MOA is 10.47".
Can you hold half an inch at a thousand yards? Can you see half an inch at a thousand yards? I can't.

Jim Watson · December 30, 2021, 08:50 PM

I was thinking like zoomie, the actual emitter is a teensy fraction.

imp · January 1, 2022, 01:17 AM

Hopefully someone more articulate can explain this better than me, but there is another point to consider.

My aimpoint claims the dot is 2MOA, and perhaps it is. However, the brightness level makes the dot expand or grow.

At its lowest visible settings, to my eye, the dot covers an area of the target roughly equivalent to 2 or 3 MOA.

At its brightest, it seems to cover 8-10 MOA. I think the popular nomenclature for this phenomenon is bloom, and the effect seems to vary slightly between sights, users, power levels, and ambient light.

Just one more thing to be aware of. For best accuracy, I try to sight mine in using the lowest power level I can.

Bart B. · January 17, 2022, 03:17 PM

Competitive shooters in the USA using bullseye targets with scoring rings spaced in inches have used the "inch per hundred yards" method for over a century. Their aperture rear sight had 40 tpi leade screws and 12 clicks per turn so a 30 inch sight radius had exactly 4 clicks to move the LOS angle exactly 1 inch per hundred yards of range

**Unclenick** · January 17, 2022, 10:45 PM

The dot is a nominal 2 MOA, or 0.0333...degrees. The angle starts with its apex at your retina. The sides of the angle, if you spin them around the centerline between them, trace the sides of a cone whose axis (that centerline) passes through the middle of the red dot and whose sides just kiss its outer edges. The sides keep spreading out as you go further from your eye. At 100 yards they have spread to two inches and change. At 200 yards, they have spread twice that much, and so on.

A simple way to look at it is, the dot covers a two-inch circle at 100 yards. At two hundred yards, where the same target looks half as big in the optic, it will cover a four-inch circle. The further away the target is placed, the smaller it looks, so the more inches that same dot covers.

As to the physical size of the dot, it depends on the design of the optic. If the the field of view is 20 mm wide and your eye is six inches from the focus, and the magnification is 1X, you have about a 450 MOA field of view, so the dot would appear to be a 225th of 20 mm, or about 3.5 thousandths of an inch. That's awfully small, so I assume the field of view is actually smaller, but the product description doesn't say.

Bart B. · February 26, 2022, 05:30 PM

The trig value below was calculated to 102 decimal places for those wanting more precision with trigonometry.

1.04719753642832854694747069666400334739860873986429
830552235157457471965151538005004775737357536725837... inches per 100 yards...

Use one inch.

**JohnKSa** · February 26, 2022, 05:49 PM

What about if the distance is 240 yards?

Then if one is fixated on using whole number values, one might assume that the correct rounded value for 1MOA at that distance is 2" when it's actually 3".

Knowing the proper value doesn't mean you have to use all the digits--in fact, as the example shows, it can be even more important to know the proper value if you're going to round.

December 28, 2021, 08:30 PM	#1
TBL004 Member Join Date: June 17, 2021 Location: Phoenix AZ Posts: 28	2 MOA RDS Anyone know the diameter of a 2 MOA RDS dot? TIA __________________ Freedom is never more than one generation away from extinction.

December 28, 2021, 09:14 PM	#2
cslinger Senior Member Join Date: July 14, 2002 Location: Nashville, TN Posts: 2,045	The “sight”??? All sights are different. You will need to be specific. (Aimpoint, Trijicon, Vortex etc. etc. ) If you are taking about the dot, 2 MOA is approx 2 inches at 100 yards. This might help as far as dot size at ranges https://cmore.com/DotSize __________________ "Is there anyway I can write my local gun store off on my taxes as dependents?"

December 28, 2021, 10:32 PM	#3
Shadow9mm Senior Member Join Date: March 21, 2012 Location: Indianapolis, IN Posts: 3,973	are you talking about the actual diameter of the dot itself inside the optic? or how big it appears on the target? actual dot size, no idea. 1 MOA is roughly equivalent to 1in at 100yds, 2in at 200 yds, 3in at 300yds. Thus a 2moa dot would be 1in at 50yds 2in at 100, 4in at 200, 6in at 300 and so on. __________________ I don't believe in "range fodder" that is why I reload.

December 28, 2021, 11:05 PM	#4
TBL004 Member Join Date: June 17, 2021 Location: Phoenix AZ Posts: 28	Was interested in the diameter of the red dot on a Holosun HS403R. Believe it has a 20mm objective lens. Thanks __________________ Freedom is never more than one generation away from extinction. Last edited by TBL004; December 29, 2021 at 10:17 AM.

December 29, 2021, 01:49 AM	#5
zoomie Senior Member Join Date: January 23, 2006 Location: GA Posts: 1,864	https://holosun.com/index/product/detail/id/132.html "2 MOA Dot Reticle" Double everything below: If for some reason you're actually asking the diameter of the dot, here's a faux scientific guess. Assuming the dot is meant to be viewed 6" from your eyeball, the dot is about 0.00349". Last edited by zoomie; December 29, 2021 at 02:18 AM.

December 29, 2021, 10:16 AM	#6
TBL004 Member Join Date: June 17, 2021 Location: Phoenix AZ Posts: 28	Thanks everyone for the replies and info. Appreciate it! __________________ Freedom is never more than one generation away from extinction.

December 30, 2021, 03:29 PM	#7
JohnKSa Staff Join Date: February 12, 2001 Location: DFW Area Posts: 24,986	A quick way to determine the size of 1 MOA, in inches, at a given distance is to divide the distance in yards by 95.5 For example, at 25 yards, 1 MOA is 25 yards / 95.5, which is about 0.26". To find the value of 2 MOA at that distance, just multiply the 1 MOA value by 2. That means 2 MOA at 25 yards is about 0.26" x 2, or about 0.52" Another quick example. At 238 yards, the value of 1 MOA is 238 / 95.5, or about 2.5" If you wanted to know how much 5 MOA is at that distance is, you would multiply that value by 5. So 5 MOA at 238 yards is 2.5" x 5. About 12.5". __________________ Do you know about the TEXAS State Rifle Association?

December 30, 2021, 03:54 PM	#8
cslinger Senior Member Join Date: July 14, 2002 Location: Nashville, TN Posts: 2,045	I did not know this. Thanks. ....The more you know. __________________ "Is there anyway I can write my local gun store off on my taxes as dependents?"

December 30, 2021, 05:05 PM	#9
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,063	The exact value is actually pretty easy to find, too, if your smartphone calculator has pi. Just remember that at 300 yards a moa is subtended by exactly pi inches. Thus, you just divide your range in yards by 300 and multiply the result by pi to get exact inches. For example, suppose your range finder tells you your target is at 750 yards: 750/300 = 2.5 and 2.5×pi = 7.85398 inches per moa. __________________ Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle

December 30, 2021, 08:48 PM	#10
Jim Watson Senior Member Join Date: October 25, 2001 Location: Alabama Posts: 18,541	A lot easier just to take a minute of angle as an inch per hundred yards. At 1000 yards, an IPHY is 10", a geometric MOA is 10.47". Can you hold half an inch at a thousand yards? Can you see half an inch at a thousand yards? I can't.

December 30, 2021, 08:50 PM	#11
Jim Watson Senior Member Join Date: October 25, 2001 Location: Alabama Posts: 18,541	I was thinking like zoomie, the actual emitter is a teensy fraction.

January 1, 2022, 01:17 AM	#12
imp Senior Member Join Date: November 11, 2006 Posts: 626	Hopefully someone more articulate can explain this better than me, but there is another point to consider. My aimpoint claims the dot is 2MOA, and perhaps it is. However, the brightness level makes the dot expand or grow. At its lowest visible settings, to my eye, the dot covers an area of the target roughly equivalent to 2 or 3 MOA. At its brightest, it seems to cover 8-10 MOA. I think the popular nomenclature for this phenomenon is bloom, and the effect seems to vary slightly between sights, users, power levels, and ambient light. Just one more thing to be aware of. For best accuracy, I try to sight mine in using the lowest power level I can.

January 17, 2022, 03:17 PM	#13
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	Competitive shooters in the USA using bullseye targets with scoring rings spaced in inches have used the "inch per hundred yards" method for over a century. Their aperture rear sight had 40 tpi leade screws and 12 clicks per turn so a 30 inch sight radius had exactly 4 clicks to move the LOS angle exactly 1 inch per hundred yards of range

January 17, 2022, 10:45 PM	#14
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,063	The dot is a nominal 2 MOA, or 0.0333...degrees. The angle starts with its apex at your retina. The sides of the angle, if you spin them around the centerline between them, trace the sides of a cone whose axis (that centerline) passes through the middle of the red dot and whose sides just kiss its outer edges. The sides keep spreading out as you go further from your eye. At 100 yards they have spread to two inches and change. At 200 yards, they have spread twice that much, and so on. A simple way to look at it is, the dot covers a two-inch circle at 100 yards. At two hundred yards, where the same target looks half as big in the optic, it will cover a four-inch circle. The further away the target is placed, the smaller it looks, so the more inches that same dot covers. As to the physical size of the dot, it depends on the design of the optic. If the the field of view is 20 mm wide and your eye is six inches from the focus, and the magnification is 1X, you have about a 450 MOA field of view, so the dot would appear to be a 225th of 20 mm, or about 3.5 thousandths of an inch. That's awfully small, so I assume the field of view is actually smaller, but the product description doesn't say. __________________ Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle

February 26, 2022, 05:30 PM	#15
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	The trig value below was calculated to 102 decimal places for those wanting more precision with trigonometry. 1.04719753642832854694747069666400334739860873986429 830552235157457471965151538005004775737357536725837... inches per 100 yards... Use one inch. Last edited by Bart B.; February 26, 2022 at 05:47 PM.

February 26, 2022, 05:49 PM	#16
JohnKSa Staff Join Date: February 12, 2001 Location: DFW Area Posts: 24,986	What about if the distance is 240 yards? Then if one is fixated on using whole number values, one might assume that the correct rounded value for 1MOA at that distance is 2" when it's actually 3". Knowing the proper value doesn't mean you have to use all the digits--in fact, as the example shows, it can be even more important to know the proper value if you're going to round. __________________ Do you know about the TEXAS State Rifle Association?