optic and red dot?

[Dr Bocci 0]

Hey guys I'm an AR newbie so bare with me.

 

I've seen a bunch of photos of ARs set up with both an optic and a red dot type sight. How does this work. Is the red set out of focus and used as a back up or is the dot in focus and used to aim?

 

Thanks. Any info on how this set up works would be helpful.

[High Exposure 5,678]

What do you mean by optic? A red dot sight (RDS) is an optic and it can't be out of focus. Also, on a gun so equipped the RDS is generally the primary sighting device.

 

If you are thinking about a precision rifle (bolt or gas) or a rifle setup for a primary role of engaging medium to long range targets, you may see an offset RDS or an ACOG with a mini red dot sight (MRDS) mounted above. In these instances the MRDS becomes a secondary sighting system that may be used as a primary optic in a different role. The magnified optic woud then be the primary sight for medium to long range precision engagement and the shooter will roll the rifle to use the MRDS/RDS as a primary sight in the event a target at medium to short range appears due to its advantage for slightly faster close engagements and greater field of view (FOV).

 

The offset MRDS works OK but takes some practice to get quick with and can be difficult to zero. It can also be confusing to use for close quarter engagements as the angle it is mounted on can mess with your ability to instinctually adjust for the AR platform's mechanical offset (sometimes called a sight line/bore line discrepancy) by changing it from its normal orientation of vertical to the bore to an angle. This can be overcome with training, but can build scars if you use multiple weapon systems and don't stay current on all of your training with them.

 

The MRDS above the ACOG is terrible on an M16/M4/AR type platform. Your mechanical offset inside 25 yards can be double (or more) what it typically is and you need to use an atrocious "chin weld" on the stock instead of the typical cheek weld. Avoid at all costs.

 

If this isn't what you were talking about, can you post a pic of an example?

[Dr Bocci 0]

Thanks High Exposure for replying to my question. Sorry if my question was a bit obtuse. What i was referring to was an eotech in front of a magnifier. See the picture i attached. I would imagine the dot on the eotech would be out of focus.

 

I've seen the offset you were referring to.

[High Exposure 5,678]

Ah, ok.

 

No, the magnifier doesn't make the dot out of focus. It does make it appear larger, but since it magnifies the target as well, the dot remains the same size relative to the target.

 

Example:

 

The EoTech has a 1 minute of angle (moa) dot covering 1"x1" of your 100 yard target*. Looking thought the 3x magnifier, the dot appears to now have tripled in size, making it a 3 moa dot, which would cover a 3"x3" portion of your 100 yard target. But... The magnifier has also magnified your target 3x, so the 3moa dot is really only 1moa relative to your target. I know, that's probably clear as mud...

 

*Quick and dirty RDS lesson - A minute of angle dot would cover 1"x1" of your target at 100 yards, 2x2" at 200 yards, 1/2"x1/2" at 50 yards, etc... - this is because the dot is projected in your optic and doesn't move, but the target can move further from you, making the target appear smaller so the dot covers more, or closer to you making the target apear bigger so the dot covers less.

 

Some people with eye problems have a hard time seeing a crisp clear dot with a magnifier and instead see a smear or comet, but that is an effect of your eye and not the magnifier.

[lexcruiser 14]

High Exposure- I always enjoy reading your posts. Thanks for that rundown..!

[High Exposure 5,678]

Thank you lex. My pleasure!

[Sonnylee 20]

High Exposure- I always enjoy reading your posts. Thanks for that rundown..!

+1 here too! I'm learning something every day!

[Dr Bocci 0]

Gotcha! Thanks High Exposure.