rings for red dot on M&P15

[Sven]

I need to buy new rings to mount a Bushnell red dot on my M&P15 flat top. The ones that came with are way too low and are for a Weaver style, anyway. So what height picatinny rings should I use -- medium, high or extra high. I would just as soon order rings only once.

 

[Foxtrot]

I need to buy new rings to mount a Bushnell red dot on my M&P15 flat top. The ones that came with are way too low and are for a Weaver style, anyway. So what height picatinny rings should I use -- medium, high or extra high. I would just as soon order rings only once.

rings > Scope Rings and Mounts - height depends on what your requirement is, you said it was too low already, so maybe medium height would suit you > http://www.primaryarms.com/product.sc?productId=1196&categoryId=220 .... or... maybe the standard AR Height > http://www.primaryarms.com/product.sc?productId=630&categoryId=220

 

[christcorp]

I didn't buy rings. I bought a "Riser". You can buy a 1/2", 3/4", or 1" riser for the picatinney. You can buy full length; approximately 5" long; or a compact; about 3" long; or even 2 individual 1" long risers that you can spread out as you see fit. This way you still maintain the original height on the rest of the original picatinney. These can be found all over ebay for less than $15. I personally prefer this than getting taller rings. The taller the rings, the less stable it is. Raise the rail instead. That's what risers are for. But if you really want taller rings, I can't help. Just wanted to mention an alternative. An option.

 

[BeginingOfTheEnd]

What cristcorp said. Someone can correct me if i'm but a 1/2" riser will let you absolute co-witness and a 3/4" will put your irons in the bottom quarter of optic. All preference

 

[Foxtrot]

What cristcorp said. Someone can correct me if i'm but a 1/2" riser will let you absolute co-witness and a 3/4" will put your irons in the bottom quarter of optic. All preference

Is this the red dot you have > Bushnell - Red Dot ??

The iron sights (center line) and red dot (center line) are only really 'co-witnessed' when they are in the same plane, which means the dot is at the top of the front sight post when looking through the iron sights (at zero). If you can do that with a 1/2 inch or 3/4 inch riser then you are co-witnessed, it doesn't matter if its the bottom quarter or not, as long as you can do that 'same plane co-witness' thing. Co-Witness for red dot sighting is co-witness, there isn't really anything such as '3/4 co-witness' or 'full co-witness' or 'absolute co-witness' in terms of the red dot, your either co-witnessed or your not. I know a lot of people think they are different, but they really aren't. If your red dot is in the same center line plane as your iron sighting center plane at zero (and of course can see the red dot and its in the proper place at zero at the top of the front post) then you can co-witness and thats it. On the other hand, the field of view of your BUIS should remain suitable too while sighting thru the red dot sight without the dot.

The easy way; Zero your iron sights first, then simply move the red dot to the top of the front sight post (actually just a tad bit of the red dot bottom ever so slightly below the very top of the post, the very slightest bit, almost touching but just a tad below touching point) and your red dot is zeroed too. Refine from there if needed.

If you call the folks at Primary Arms they can tell you exactly what you need and probably already have it. I know that some people have used the LaRue mounts (and I think some Daniel Defense mounts too) on the Bushnell and it worked fine. I know people use risers sometimes but personally myself i'd use a correct set of mounts and not a riser, but to each his own.

 

[christcorp]

The 3/4 isn't in reference to co-witnessing. It's a 3/4" riser. I use a 1" riser, and my iron sight co-witness about 1/4th of the optics. Enough that it works for me. If I was to use a 3/4" riser instead of a 1", the co-witness would appear about half way up the optics. Which riser to get, depends on the iron sights you're going to use. Either way; I recommend a riser instead of taller rings. It's cheaper and more stable.

 

[Foxtrot]

There is a thread in the 15-22 forum that might give you an idea of what your 1/3 co-witness would look like > http://smith-wessonforum.com/smith-wesson-m-p-15-22/132223-absolute-co-witness-1-3-co-witiness.html

Look at post #9 in that thread from Kirtsky. See that red dot scope? Thats an Aimpoint T-1. The Bushnell red dot (In the link I posted previously) is similar for the red dot center line as the Aimpoint T-1. The co-witness happens in the lower 1/3rd of the red dot sight. Does that give you an idea?

For the same 1/3 lower co-witness, Primary Arms has a Cantilever mount for $24.99 > Primary Arms High Cantilever 30MM Mount

If your going cheaper than the $24.99 for the Primary Arms Cantilever mount, your probably going with risers then and using the rings supplied with your Bushnell Red Dot.

My first thought for this type of weapon is always tactical use. I don't use risers myself, and don't know anyone in a tactical use that uses them either but there are those that do, so risers are not my first choice. The reason for not using risers as a matter of routine (some things just need them though sometimes) in tactical is for many reasons but some of them are to lessen possible failure points. The more vertical you go with a device the more prone the mounting system or device is to damage or failure over time as simple physics takes over and causes more stress and the more vertical height on a weapon device the harder it is to sling comfortably or quickly without damaging a device eventually. Another reason is to keep the weapon as close to its intended use sighting profile as possible, and to not add vertical bulk and keep the lower weapon physical profile. There are other reasons as well. The M-4 weapon was created with a certain intended sighting profile (cheek in a certain area, sights along a certain line, certain field of view around optics and sights, etc... These reasons, and others, are why you see the military choosing more lower profile sighting systems like the MARs system, and why designers of military sighting systems try to make things as low profile as possible, and also why EOTech form type optics are more acceptable for tactical, so we try to maintain as close to that as possible. And thats why I don't use risers or recommend them as a first thought.

 

[Sven]

Thanks for the replies. The Bushnell red dot I bought is this one: Bushnell - Red Dot 1x 28mm Red/Green Dot [730135] (I can't remember how to use just words for the link ). The green dot looks like it will work well for extreem low light coyote hunting and the red for daylight. I think I'll like having a choice of dot sizes, also.

Anyway, I agree with Foxtrot on the risers, plus the rings that came with the red dot are Weaver-style, not picatinny. Thanks for the links to Primary Arms, but I think I'm going to pick up a pair of Weaver picatinny from MidwayUSA for about $30. From the discussion it sounds like I want the "extra high".

Thanks again.