Stupid optic question

[craigthomasreed]

Got my Sport II few weeks ago and pulled grabbed the Vortex Sparc red dot.

My sport has the MBUS rear flip up sights and wondering how do I instal the Vortex to play with both rear flip up and from A2? Or do I?

Do I just keep rear sight flipped down? Remove completely? Or do they all work together?

Sorry for noob question and thanks in advance for any help -


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[tcon]

The MBUS is typically a backup in case the optic becomes unusable. I would sight-in the MBUS aperture and get comfortable using them and then properly mount the optic and fold the rear down as a just-in-case option.

 

[Steve_in_PA]

On my Bushmaster, I have the Aimpoint PRO mounted on the rifle. I get a lower 1/3 co-witness. I keep the BUIS folded down. If I need it, I just flip it up. Personal preference, as I could easily keep the BUIS up, but prefer it folded down.

 

[ChattanoogaPhil]

Did the Sparc not come with a riser for an AR platform to co-witness with the irons?

As far as mounting... you can mount it anywhere on the receiver you prefer, but the standard position is far forward on the receiver.

 

[cyphertext]

The red dot and the backup sights are independent sighting systems. You don't typically use them "together", but let me explain. You should zero each set independently. I would first zero my backup sights at 50 yards. Once I have those zeroed, I would mount the optic. I can get the optic fairly close by looking through the backup sights and placing the dot right on top of the front sight post... doesn't matter if they are absolute co-witness or lower 1/3rd. Then fold the rear sight down and confirm zero on the red dot. I like to use the 50 yard zero for both.

With a red dot, since there is no magnification, you can turn the dot off and use the iron sights, looking through the optic.

 

[craigthomasreed]

Thanks guys! That helps! By "zero"ing in you just mean sighting them for accuracy at 50 yards? Will post pic tonight -


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[tcon]

Yes - For fixed sights, 50 yards POA/POI (point-of-aim/point-of-impact) is a popular sight-in distance for M193 and M855 ammo because of its flatter trajectory within the 250 yard range. With my iron sights, it's what I use and it's what I would use if I had a red dot.

So with "F" height sights sighted in at 50yd (near zero) and 200m (far zero) here is the bullet path (plus or minus): 0-20 yards is 2" low, 50yd POA=POI, 140 yd is 2" high, 215yd POA=POI, 250yd is 2" low. So even without hold-overs and hold-unders out to 250 yards, you are going to have an effective shot if a +/-2" POI is acceptable. If you need tighter hits, commit to memory the 2" hold-over numbers: 0-20 yards and 250 yards and also the hold-under of 2" at 140 yards.

 

[soonerwink]

Did the Sparc not come with a riser for an AR platform to co-witness with the irons?

As far as mounting... you can mount it anywhere on the receiver you prefer, but the standard position is far forward on the receiver.

My Sparc 2 came with a riser that you could co-witness or 1/3 witness.

 

[craigthomasreed]

My Sparc 2 came with a riser that you could co-witness or 1/3 witness.

Thanks!

My battery compartment was impossible to remove...

Also this wire is loose? Not sure if I can just clip it or what?

 

[craigthomasreed]

Can I put some sort of lubrication? Or what? That wire like cinches the cap so it can't turn counter clockwise..


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[tcon]

Those wires are retaining tethers so you don't loose the caps. It looks like they should ride and slide in the channel. Righty-tighty, lefty-loosey so see if you can position the slip knot all the way clockwise with something that doesn't scratch -toothpick maybe, and then turn the caps counterclockwise to loosen. These things are usually soft alloy so be careful of any tools you will be tempted to use or you will mung up the knurls.

 

[craigthomasreed]

Thanks yeah I had to use some pliers to get it. It came off and I put some anti seize on the threads and screed back on. Goes on smooth and gentle but then the second I try to unscrew the wires like seize the cap up in counter clockwise rotation. Weird. I contacted seller and they said probably defective. No other issues lights up fine and attaches great. Absolutely love it.

Don't want to send it back, maybe I'll worry about it when this battery dies?

Also, the wires have nothing to do with battery connectivity or anything right? Why use wound up wires then?


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[warriorking]

I ordered a Vortex Strikefire 2 today and will set mine up with a 1/3 co-witness....

 

[craigthomasreed]

Why do people do 1/3 vs absolute? Probabaly dumb question


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[McE]

Why do people do 1/3 vs absolute? Probabaly dumb question


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1/3 gives you a more unimpeded field of view through your dot sight during normal use. I recommend this if you do most of your shooting with a functional dot sight.

Absolute gives you a more unimpeded field of view through your dot sight when you're using irons through the disabled/turned off dot sight.

Someone will be along shortly to disagree with me.

 

[C J]

I ordered a Vortex Strikefire 2 today and will set mine up with a 1/3 co-witness..

I think the Strikefire only comes with a 1/3 lower co-witness mount. The SPARC can be set up either 1/3 or co-witness. The Strikefire is bigger but it can be found cheaper so it's a trade off. It only adds a few ounces of weight. It's not that much longer either plus it has a bigger view area according to what I've read.