I just ordered a Tasco Red Dot and was wondering if it needs a riser or if it can be attached to the top rail? If it needs a riser, what do you recommend? Ideally, I want the red dot to co-witness with my iron sights. I am just looking for something inexpensive that will do the trick.

Thanks!

I have looked at them and if you have fixed iron sights you will most likely need a riser. If you have MBUS or folding BUIS you can probably get away without using a riser but the height over bore will be low, similar to an EOTech.

Tasco makes a lot of red dots. If it's one of the typical BKRD series with a built in mount you'll be able to mount it on the rail. The issue will be that it's too low to comfortably see thru it. Suggest using a 3/4in tall riser for lower 1/3 co-witness. That said, it would be easier to offer suggestions if you mentioned what optic you ordered. It's like asking what tires fit on a Ford.

My guess was that he was talking about this one:



It will be low without a riser.

Yes, that is the red dot I purchased. I am going to mount it on an M&P 15-22. I tried searching for risers but wasn't able to determine (a) which height to get for co-witness and (b) a relatively inexpensive one since it's just for a 22lr.

That is the BKRD series.

3/4in risers cost about $10

-- Chuck

Yes, you'll probably want a riser.


I'm using this one:
Leapers UTG Deluxe Medium Profile Picatinny-Style Riser Mount AR-15 Flattop Matte - MidwayUSA

Crazyfingers, is that a 30mm or a 42mm?

It's this guy:
Tasco Red Dot Sight 38mm Tube 1x 30mm 5 MOA Dot with Weaver-Style Mount Matte - MidwayUSA

I had one. To cowitness you will need a riser.

.75 riser works the balls. it isnt a have to have, but it helps keep your neck from breaking. and 3/4 is just right for co whitness

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Great info. I had been looking at that very riser. Thanks much. Cool username, BTW. Reminds me of a song I know.

Hey guys will a 3/4" riser also work with a TG8030p, and TG8030TB RD? these are both truglo's. on one rifle i will have magpul bus with the TB model, the other rifle will have the stock sights from the 15-22 with the P model. will a 3/4 inch riser work to co-witness with both sets of sights, or will i need a different size for each? thx for your help guys.

I should know this....on the pics showing the Tasco, they seem rather far far away fron the posistion the eye would take while aiming.
What happens to eye relief?
I have a 4X lepears armor 2 tone recilce, and the eye relief requires the scope to be almost even with the charging handle handle, way closer than these pics of the tasco.

I've never used a red dot on my 15-22, Am I missing something?

Sorry for the stupid question, I always wanted my optic to co-witnise with my stock irons. I just can't get the eye relief anywhere near correct w/o having the darn this so close/

I like some magnafication, thats why I bought the 4x Leapers. It shoots and zeros great. I can look thru the mount, but I can't mount the irons, rrrrrrrrrrrrrrrrrrr. Help.

Please help.

Mark

Unlike a magnified scope a red dot has no real eye relief. In fact the farther forward on the rail the better.

The red dots are a both eyes open sight aquisition and let's you focus on your target while still keeping the red dot in line with the target.

I use a 3/4" riser on the red dot using the stock sights and have an absolute co-witness, so you will need a riser.

Pinstripe is right on. The only thing to add is that you can't co-witness with a magnified optic.

The top pic is my Sig with a 4x scope. Just like your 4x it requires mounting for about 3in of eye relief. No iron sights can be use for co-witness. The front sight would be just a ghosty blur.

The bottom pic is my 15-22 with a 1x red dot (no magnification). Notice how far the red dot is pushed out on the receiver. The riser under the red dot is to lift the red dot up high enough so that it's like a window to see through for the iron sights when they are flipped up for use.



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Phil does your red dot co-witness with your magpul sights? if so high of a riser do you have on there?

Yes it does, but the riser is specific for this particular optic. It's not a generic rail riser. It's a Primary Arms MicroDot.

Primary Arms Micro Dot (Gen 3)

So would it be ideal if i looked for a truglo riser knowing it is for my optic?

Just out of curiosity, why do you want your red dot to co-witness with your MBUS? Do you plan on using them at the same time? Or, do you mean by "co-witness" just being able to see the front sight post through the glass of the red dot, when it is turned off?

I think you mean to ask, why do i want my red dot to co- witness with my mbus? i dont want to be using my red dot and the battery dies then im stuck with no sights. later on when i can afford a magnified scope i will set that above my mbus and zero the scope in at 100 yards and the mbus at 25 yards.

But for now i have the extra red dot so i might as well make do with what i got.

OK, so you just want to see the MBUS through the glass of the red dot for now. When I had a Truglo red dot on my 15-22, the MBUS co-witnessed through the glass with NO riser under the red dot. It was an open reticle red dot with the standard Truglo base. here's a pic:

unfortunately mines is not an open reticle. this is the one i have

http://www.cheaperthandirt.com/60606-34.html

I'm gonna get a 1/2" truglo riser and hopefully with some luck it will co-witness with my mbus.

ill post an update just incase some one else runs into the same problem.

I didn't think the fact that it was closed reticle or open reticle had anything to do with it. Only the height of the reticle itself. Looks like your Truglo mount is the same as mine (approx), but hey, if you can't see the front sight, then you can't see it. Good luck with the riser.

OK, so the 3/4 riser is available in a one piece mount with easy off lever for a red dot? All one piece? And then I can put my stock sights back on?

Sorry for being so numb, but I order on line and can't visualize
and handle the parts.

If you feel like it, could you link me to the red dot and easy off riser that works?

Thanks again.

Mark

Here's one source for the quick release riser.
ARR-591 - AR-15 Quick Release 3/4 " Riser Mount 5.25" of Rail Space

I had an NCStar 1x30 red dot w/ the Leapers 0.83" riser and found it a bit high to co-witness with my irons. I was just gonna deal with it until the red dot took a dump, so I'm sending them both back and exchanging for another red dot and the 1/2" riser.

I'll post the results between the two risers once I receive the 1/2".

thx alot i'm still waiting to get a riser for mine. i dont want to buy the wrong one.

1. Your sights are about 1 3/8 inches high (tip of the front sight post/center of rear aperture) from the top of the rail. Grab a measure and check for yourself. (Measurement A)

2. Mount your red dot.

3. Measure from the top of the rail to the center of the glass of your red dot. (Measurement B)

4. A - B = Minimum riser height. Any shorter than minimum and your sights will be too high into the glass of the scope. You can get a taller than minimum height riser as long as your red dot has large enough glass to accommodate. Measure it. I like to have my sights in the lower third of the glass rather than the center line of the glass. Either way will work, but you don't want your sights much above the centerline.

Riser heights are made in 1/2, 3/4 and 1in heights. Once you put a measure to it the concept of risers will become very simple.

If i can ask y do you like the sights in the lower third of your glass? my idea to do that would be to have my RD zeroed in at 50 yards and the sights zeroed at 25 yards. Is this ideal?

Below is a 3/4 inch riser I use. It is a polymer riser from Tapco. It matches the rifle finish perfect and cost $10. It has thumb screws for easy on/off mounting, and because it is polymere you can regularly take it on and off without worrying about boogering up the rifle's finish.



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Yes, I prefer lower 1/3.

Sure, you can zero your iron sights and red dot independent of each other. However, 25/50 will be near the same.

Ok so then why the lower 1/3 of the glass?

i'm sorry if this is a dumb question or if its bothering you that i'm asking this, i'm just trying to figure out the logic behind the lower 1/3 of the glass

The reason I prefer it is because when I use iron sights the top of the red dot tube isn't blocking my downfield view of the target area so much. The MicroDot I use has a really small tube.

My advice is to not sweat this stuff. Grab a 3/4in riser, slap it on and go to the range. There will be lots of stuff you learn that you like and don;t like about your red dot and these type of sights in general. Did you know that you can completely look over the top of the rear sight through the red dot scope and the red dot will still be on target just the same as when you look through the rear sight aperture to the red dot? You'll have fun learning.

ok.

1 more question, are your sights and red dot zeroed in to the same distance or do you have them zeroed different?

Once again sorry for all the questions. I am new to shooting and all the info i find here and all the people willing to answer all the little questions are just great. I have yet to find someone not willing to help.

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.

ok I got it. thanks alot phil i appreciate it.

I'm not sure of the ammo you're running, but I mainly shoot the Winchester SuperX 36gr. HP 555, from Wally's. These rounds have a trajectory of 0.0 @ 25 yards AND 45 yards. That will leave your other sight/s available for a longer range such as 75 or 100 if a co-witness isn't priority. As Phil stated, 25 and 50 are pretty close.

Just a thought.
D.

I agree with chat, if you have a small tube the irons will block the view down range, and draw your eye. I have a big cheapo tasco so I use the 3/4 also handy in hot indoor range when sweat gets too bad to squint just line up the dot and go.

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

__________________
Air Assault!

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

__________________
Overkill is Underrated

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?

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

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

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.

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

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.

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