AR Sponsor
Posted: 11/3/2015 1:26:00 PM EDT
| New user and Bushmaster M4 owner with truglo red dot optic. Dumb question: How do you use the optic with the front sight? Do you use the windage and elevation adjustments to put the red dot on the top of the front sight? I went to the range and did not even hit the target at 50 yards because I did not know how to use the optic. Thanks to anyone for help. |
|
No question is dumb. We've all been there. And, we've all benefited from the inordinate patience of members of this board who are graceful enough to help us understand the AR15 system. Stick around and you'll meet some great guys and gals and virtually no on here is intent of being a smart butt.
There's no need to use any part of the iron sights in order to zero a red dot scope (RDS). Just ignore the irons, sight the red dot on the bullseye (point of aim, POA), fire a round and then adjust the scope's elevation and windage until the POA and point of impact (POI) coincide. They you're done unless you want to use backup iron sights. If you want backup iron sights you can co-witness the RDS with the irons. There are two types, bottom-third cowitness and absolute cowitness. With bottom-third cowitness you put a relatively tall riser on the RDS so the line of sight (LOS) through the irons is in the lower third of the aperture of the RDS tube and the red dot is either in the center of the tube or slightly above it. Then zero each sighting system independently or one another. This way the RDS is the primary sighting system. But if it fails the iron sights are immediately available to you in that emergency. With absolute co-witness the RDS is mounted with a riser that is somewhat shorter than the one you use with lower-third cowitness with the results that the LOS of the iron sights, essentially, sits in the middle of the RDS tube. Then you zero the irons in the usual way at whatever range you choose. It's best to turn off the RDS when sighting in the irons as the dot can be distracting. Assuming you're using the "apple on a fence post" means of zeroing the irons (target bullseye's lower edge rests atop the top of the front sight post (FSP) when the irons are sighted in) rather than a deadhold (top of iron FSP rests dead center of target bullseye) then to get the RDS to absolute co-witness you just adjust the RDS elevation and windage so that the red dot rests atop the FSP like it was the target bullseye. Then you fold down the irons and verify with the RDS that your RDS POA is coincident with the POI. Then you're done. Well, almost done. It's best to then convince yourself that you needn't use any form of sight alignment with the RDS. You should prove to yourself that as long as the dot is on the bullseye NO MATTER WHERE THE DOT IS IN THE RDS APERTURE you can still hit the bullseye. So, shoot a 4 - 5 shot string with the red dot in different places in the RDS aperture and verify that the POI is the same or very nearly the same. For my RDS that's true as long as I don't put the red dot at the very margin of the aperture and fire. Even then, it's very close to POI = POA. Best, LF |
|
OP: Is your red dot on a riser or directly on your rail?
Most dots need to sit on a 1" high riser. That typically gets a zeroed dot up above the iron front sight. That is sometimes called "lower 1/3 cowitness.", as mentioned above. A little lower riser, about .825" high, will line up the zeroed dot with the pathway of the front and rear sights, called "absolute cowitness". But, as stated above, either way, ignore the front sight when zeroing the dot. |
| Thanks, but the problem is that the front sight gets in the way of the red dot. In other words, the red do is on the front sight so there is no way to see if it is even on the target. I can see the red dot above the sights only if I move my eye to the top of the scope and then the red dot is way off. If I raise the rear sights (pinhole sight) then the red dot is right on top of the front sight but that sort of defeats the purpose of a red dot optic. |
|
Is this your red dot and mount setup right here?
http://shop.opticsplanet.com/truglo-red-dot-30mm.html?utm_source=google&utm_medium=cpc&utm_campaign=plusbox-beta&gclid=CODc-4_I_MgCFZUlgQodkSENrQ If so, the riser on it may not be tall enough for a co-witness with irons. Sorry but i'm not familiar with that optic. That being said... 1st, make sure your optic is installed and tight (not over tight) with blue loctite. I can't tell you how many optics newcomers i've seen unable to get a zero due to loose mounting, or a mounting coming loose bc they didn't use loctite. 2nd, forget about the front sight and rear irons and look through your RDS with both eyes open, you should be able to superimpose the dot over the target and see both the dot and the target. The front sight should be a blur. When zeroing, i prefer a large target (i.e. a big green walmart silhouette) to get my first shots on paper at 50 yds. If it's way off i'll move it in to 25, get it on paper, and move it back out once i have it close. Once you get your first hits on paper, use the adjustment knobs to walk the bullet impact to point of aim. It helps to use one of those orange, round sticker targets so you have a consistent point of aim. Once you have your red dot zeroed, you should be able to co witness your irons to the red dot by looking through the rear peep and adjusting them to where the align with the dot. |
|
Quoted:
Thanks, but the problem is that the front sight gets in the way of the red dot. In other words, the red do is on the front sight so there is no way to see if it is even on the target. I can see the red dot above the sights only if I move my eye to the top of the scope and then the red dot is way off. If I raise the rear sights (pinhole sight) then the red dot is right on top of the front sight but that sort of defeats the purpose of a red dot optic. Its not a laser. The dot isn't projected o to the target, it's just your aiming point. |
|
Quoted:
Thanks, but the problem is that the front sight gets in the way of the red dot. In other words, the red do is on the front sight so there is no way to see if it is even on the target. I can see the red dot above the sights only if I move my eye to the top of the scope and then the red dot is way off. If I raise the rear sights (pinhole sight) then the red dot is right on top of the front sight but that sort of defeats the purpose of a red dot optic. That's why I asked above how you have it mounted. If you put the sight directly on your receiver, without a riser under it, your front sight will block and your rifle stock will put your head up too hign, making things even worse! Your dot needs to sit on a riser, bringing it up about an extra .825" to line up with the top of the front sight or 1" to put your dot above it and the top kf tbe front sight visible toward the bottom of your dot's field of view. |
|
Quoted:
How do you embed a picture in one of these posts? http://www.ar15.com/forums/t_1_5/876558_.html |
AR Sponsor