How do I know if I need a riser rail?

[dashadow]

Just bought a Sight Mark Holo/Laser sight for my AR, and was wondering if I should mount it right to the flattop, or should i use a riser rail? How would i know if I need one? How high, etc?

Thanks in advance.

 

[c919]

I don't know, but I need the same info. I will be checking this thread but if you find out somewhere else would you post the answer or PM me?

I'm getting my first AR soon and I want to order a new sight at the same time, and it would really suck to get the wrong one.

 

[rbernie]

You actually have to mount the optic and see if you can get a proper cheek weld and see thru the sight normally. If not, then you need to move it up/down appropriately.

 

[Dallas Jack]

I just put a red dot sight on my AR15 and had to instal a riser on the rail in order for the red dot to line up with my iron sights. Haven't shot it yet but it should work OK. I had 2 different risers. One was to high. The other lined up fine.
Dallas Jack

 

[highorder]

Install your sight. Close your eyes, and shoulder your rifle naturally and comfortably.

Open your eyes, and it should be clear if your sight is too low.

 

[cz85cmbt]

The straight stock setup obviously raises your cheek higher than a sporter type stock, or those you see on the sks and m14. Iron sights, flip ups and carry handles are made to sit on the flat top where you will be mounting your optic and they sit about 1+ inches above the bore. Scopes are harder, because of eye relief, to get perfect height on but with a reflex sight as long as you get it up off the flat top you'll be fine. That being said I know some shooters who get a good cheek weld and just tilt their head forward to lower their line of sight to see red dots that are mounted right to the carry handle.

 

[jhmc0302]

Is an Acog a good sight for a guy w/bifocals?

 

[kappelmd]

I just put a red dot sight on my AR15 and had to instal a riser on the rail in order for the red dot to line up with my iron sights. Haven't shot it yet but it should work OK. I had 2 different risers. One was to high. The other lined up fine.
Dallas Jack

I agree with "highorder", See Post #5, and you want to keep the sight as closest to the line of the bore if possible.

 

[Dallas Jack]

For me "close to the bore" made it too low as in getting my eye low enough to use the dot. Also without the riser (red dot would be lower than BUIS) I would be looking at the back of my front sight for 3/4 of the view though my red dot.
Dallas Jack