New AR Owner - Need Help with Iron Sights

[zumihopa]

I am a new owner of Spikes Tactical M4 16" Carbine. It comes with a 9" BAR rail on the barrel and that is sitting at the same level as the top rail on the upper receiver.

I bought UTG iron sights; MNT 951 (rear flip-up) and MNT 751 (front flip-up). I asked Leapers (the company that owns the UTG brand) and was told MNT 751 is the high profile front sights (height of 1.66"), as opposed to MNT 751L, the low profile front sights (height of 1.38").

I tried to zero my rifle at the range and it shoots way, way too low. I adjusted the front sight post so that I am shooting at the highest possible point but I still shoot inches (even feet) low.

Am I using the wrong front sight? Even if the answer is yes, I don't know if the low profile front sight MNT 751L will do the trick since the difference in height is only 0.28" according to Leapers.

Can anyone help out this newbie, other than telling me to buy the Magpul polymer flip ups or the really expensive Troy sights?? Thanks!

[GeoffLinder]

Align the bore (remove lower and then remove bolt carrier group from upper so you can look down the barrel) with a target center at about 60 yards. Look through the sights. If the target center (10 ring circle) is not sitting right on top of the front post like a lollipop, then you have a problem. If the FS post sticks up through the target center, the FS is too high, if the top of post is way below the target center, then the FS is too low. Do this with the rear sight a click or two up off the bottom of it's adjustment and start with the FS all the way down, then run the FS through it's range of elevation while leaving the rear elevation alone. If FS all the way down has it still sticking up through target center, get a lower front sight by the amount of FS you see sticking up, or other way around if FS is too far below and it's max elevation still won't provide the lollipop you are looking for.

[zumihopa]

Iron Sights Advice

Hi,

This is great advice! Thanks! I need some clarification, if you don't mind.

1.) My UTG rear sight only has windage and I don't think elevation can be changed on the rear sight. Would it make a difference in relation to your advice?
2.) If you have my AR and assume no iron sight has yet been bought, what front and rear sights would you buy?

Thanks very much!

[scotty99]

You have the wrong front sight. The L model is for flush rail mounting. The model you have is for mounting to a railed gas block, which sits lower than a "monolithic" rail that matches the upper's rail height. At 100 yards that .280 height difference should have you shooting more than two feet low (although you should zero your irons somewhere between 33 and 50 yards depending on who you ask).

There is a reason why Troy and Magpul command so much of the market, but honestly, I've been pretty happy with most of the UTG stuff I've bought. I would just swap out for the correct front sight before I started spending more $$. That said, the Troys are really great sights.

[GeoffLinder]

You have the wrong front sight. The L model is for flush rail mounting. The model you have is for mounting to a railed gas block, which sits lower than a "monolithic" rail that matches the upper's rail height. At 100 yards that .280 height difference should have you shooting more than two feet low (although you should zero your irons somewhere between 33 and 50 yards depending on who you ask).

There is a reason why Troy and Magpul command so much of the market, but honestly, I've been pretty happy with most of the UTG stuff I've bought. I would just swap out for the correct front sight before I started spending more $$. That said, the Troys are really great sights.

After looking up the parts you have, I agree with the above.

As for what distance to zero irons, there are several schools of thought, depending on what distances you want to be able to use them at. If you don't shoot past 200 yards much, the 55-60 yard close zero will put you about on at 200 (bullet weight depending). If you shoot out to 300 and beyond then the shorter initial zero distance (35-40 yards) will put you on at 300. The advantage with the 300 yard zero versus the 200 yard zero is that you don't have to use holdover at 300 which causes the post to occlude that actual target with a 200 yard zero on the sights. The downside to the 300 yard zero is that you will now have to use a good bit of hold-under at 100 yards (about 5 inches) and just a little bit at 200 yards. For general target shooting I would go with the 200 yard zero, for shooting to maximum range the 300 yard zero is a better way to go.

Myself, I would prefer something like this for the rear sight:

http://www.armalite.com/ItemForm.aspx?item=E20149&ReturnUrl=Categories.aspx?Category=b5d84597-3666-4326-89c9-15fac1afdf18

A full clamp on carry handle sight offers several advantages, 1st, it's very robust and much less prone to damage in rough handling compared to an unprotected rear. 2nd, it has a very wide range of elevation adjustment which allows you to crank on the elevation needed instead of using hold-overs for extreme distances.

[zumihopa]

Thanks scotty99

scotty99,

thanks! just to clarify, you mean I should have used the MNT 751L (height 1.38") instead of MNT 750 that I have (height 1.66")?

I was actually trying to zero at about 28 yards (which is 25 m). I will also look into zeroing distance of 33-50 yards. Thanks!

[zumihopa]

Thanks again GeoffLinder

After looking up the parts you have, I agree with the above.

As for what distance to zero irons, there are several schools of thought, depending on what distances you want to be able to use them at. If you don't shoot past 200 yards much, the 55-60 yard close zero will put you about on at 200 (bullet weight depending). If you shoot out to 300 and beyond then the shorter initial zero distance (35-40 yards) will put you on at 300. The advantage with the 300 yard zero versus the 200 yard zero is that you don't have to use holdover at 300 which causes the post to occlude that actual target with a 200 yard zero on the sights. The downside to the 300 yard zero is that you will now have to use a good bit of hold-under at 100 yards (about 5 inches) and just a little bit at 200 yards. For general target shooting I would go with the 200 yard zero, for shooting to maximum range the 300 yard zero is a better way to go.

Myself, I would prefer something like this for the rear sight:

http://www.armalite.com/ItemForm.aspx?item=E20149&ReturnUrl=Categories.aspx?Category=b5d84597-3666-4326-89c9-15fac1afdf18

A full clamp on carry handle sight offers several advantages, 1st, it's very robust and much less prone to damage in rough handling compared to an unprotected rear. 2nd, it has a very wide range of elevation adjustment which allows you to crank on the elevation needed instead of using hold-overs for extreme distances.

GeoffLinder,

Great info on the different zeroing distances. I will definitely rethink the re-zeroing process.

If, someday, I get the Armalite carry handle sight you recommended, which front sight should I use? The MNT 751 or the lower height MNT 751L or something different altogether? Thanks!

I think another reason I did not think about the carry handle was because I might want to have a red dot type sight in the future. if i want to use one of those ore "modern" optics, do you still recommend the carry handle or not? what eotech, red dot or "modern" optic would you recommend a newbie? Thanks!

[GeoffLinder]

GeoffLinder,

Great info on the different zeroing distances. I will definitely rethink the re-zeroing process.

If, someday, I get the Armalite carry handle sight you recommended, which front sight should I use? The MNT 751 or the lower height MNT 751L or something different altogether? Thanks!

I think another reason I did not think about the carry handle was because I might want to have a red dot type sight in the future. if i want to use one of those ore "modern" optics, do you still recommend the carry handle or not? what eotech, red dot or "modern" optic would you recommend a newbie? Thanks!

If you only want iron sights on at any given time, the carry handle is best IMHO, if you want a co-witnessed or simultaneous RDS then the naked rear is the way to go, either way, a rear sight with windage and elevation adjustment is the way to go IMHO

Unless you have a gas block with rail top, you need to use a FS that is .280 lower in height when it is mounted on the handguard rail. I always prefer a post type FS rather than an aperture.