Does the Tasco Red Dot need a riser?

[Scuds03]

Same zero. First I zero my iron sights. Then I look through the rear sight aperture while adjusting the red dot till it is on the front sight post.

ps. We all ask questions... lots of em... feel free.

We do this with our Aimpoints..we call it lolli-poppin the dot onto the front post. How cute.

 

[Redbulladdikt]

My guess was that he was talking about this one:

It will be low without a riser.

i am using this cheap-o red dot without a riser--had to place it farther forward to get the up/down correct but havent had any issues--it is going to be replaced with a used Trijicon when my buddy finished his EoTech build so the $40 price at the local Wal Mart suited fine

 

[TylorR]

So using this same Tasco red dot as pictured, to get a lower 1/3 cowitness with irons, i'd need a 1" riser? And with MBUS, no riser?

 

[Kayback]

No. Yes. Sort of.

It depends on what you want. The sight line of the AR-15 is meant to be 2.5" above the bore. That is what the stock is set up for with a correct cheek weld. To be able to comfortably use the standard height stock the main view area of your sight, either iron or optic, should be roughly 2.5" off the bore.

Most bore to rail height is about 1.1". So you need a sight that will be about 1.5" high to work correctly.

If you sight is 1.5" high at the dot, like some are, you don't need a raiser. If it isn't, you will.

Or you'll be holding the gun funny.

I know the 15/22 isn't a real AR, but those number are close enough.

With fixed sights you are stuck with a co-witness or extremely high sight heights to clear them, which can lead to bad shooting posture as well. A folding sight lets you "clear up" your view area.

The 1/3 or absolute co-witness is another story completely.

KBK

 

[TylorR]

Alright, thanks for your response, looks like i got a little more thinking to do

 

[Kayback]

With the flip sights up you'll need the same riser as you would with fixed sights if you want a co witness. If you aren't using a riser when you flip the sights up they might not be visible through the sight tube.

As I said in another topic I use the lower 1/3rd co witness (where the irons are visible in the lower third of the red dot sight tube, the red dot is above everything) with fixed irons to keep the view field less cluttered.

If I have folding sights I use an absolute co witness (where the dot is in line with the iron sights) because I can fold them down to have less clutter. Because I use a close to competition over the top grip I can press the Magpul release and use the front iron and the micro red dot tube as a crude rear ghost ring good enough for close quaters.

That might not work too well with the bigger tubes though.

 

[TylorR]

i've got the irons now and am looking to pick up a set of MBUS's if i can find a set cheap. A buddy here at work has a tasco red dot i like, but havn't shot anywhere but an indoor range so far.

I'm wanting a lower 1/3 cowitness ideally and it's just a plinker for me

 

[rraisley]

Based on actual dimensions of my MOE, the rail is 1.21" above the barrel centerline, and the rear sight height is 1.45", meaning a total height of 1.76". For my scope, I used a Burris PEPR QD mount which is 1.00" from top of rail to bottom of 30mm scope tube, making it 1.59" to centerline of scope, which works great with my MBUS sights folded. My red dot is a Primary Arms M3, also with 30mm tube. My mount for it is a NcStar MARCQ QD mount, which is 0.95" high, to centerline of it is 1.54" above the rail. Meaning it gives me about lower 1/3 co-witness, as it's 0.1" below the MBUS height. This also works great. All three are within 0.14" of each other, so cheek weld is constant. I can co-witness with the MBUS and my red-dot, if I like, or fold the MBUS down and use it, or the scope.

Note that the 0.95" and 1" dimensions on the mounts mentioned above are NOT really "riser" dimensions. A riser, technically, is an added, inserted mount between the rail and the scope mount, and the final centerline height will depend on what the scope dimensions are, assuming it has a mount already.

 

[Kayback]

Ah I was thinking of something like the La Rue risers. LaRue Tactical Aimpoint Micro Mount, LT751

The scope (red dot) attaches to it "permanently" and the whole unit is quick release, as opposed to a section of raised rail.

KBK