Sight height problem

[Dwight]

Hello all! Love my XCR Light in 5.56mm. I had a small problem with occasional light hammer strikes but Terra got me straightened out on that. A new bolt and still running at 0 percent failure rate after over 400 rds. I took it out to the range today and with my scope was able to hit steel gongs out to 400 yds with no problem, even managed a few offhand hits at 300 yds.  I was using mil-surp 55 gr South African ammo. So I am happy with my scope set up, but my iron sights are an issue of concern. I have my rifle set up with the following:

Burris AR-P.E.P.R. 1-Piece Extended Scope Mount Picatinny-Style with Integral 30mm Rings Flattop AR-15 Matte

Leupold European-30 Rifle Scope 30mm Tube 1.25-4x 20mm German #4 Reticle Matte

GG&G Flip-Up Front Sight with Locking Detent Gas Block Height AR-15 Aluminum Matte
Product #: 874162 This is a Midway USA part #

GG&G Multiple Aperture Device (MAD) Flip-Up Rear Sight with Ranging Window AR-15 Flattop Aluminum Matte

My problem with the iron sights is this. With scope removed and the rear sight set on "0" and the front sight post screwed all the way down, the rifle shoots several feet low at 100 yds. Even with the rear sight set on 6, the rifle is still about 2.5 ft low at 100 yds. So I thought I needed to raise the whole rear sight quite abit. So I added a Burris 1/2" Picatinny Riser Mount. With this set up I found with the front sight post all the way up and the rear sight set on "0" I was now about 3 feet high at 100 yds. Just for giggles I took the riser block back off and removed the front sight post completely. Using the base between the wings of the front sight and centering it in the rear sight aperture I was able to find the correct sight height t be on at 100 yds. It would appear to me that the line of bore and the line of sight difference between an AR-15 flat top and an XCR is off just enough that my front sight will not allow me to zero with or without the use of a riser block. My experience with aperture sights is sufficient to allow me to know how to properly adjust and shoot them I would venture to say. With the riser block the rear sight is too high to allow me to zero, and without it the rear sight is to low. If I could lower the front sight about .25-.35 that would allow me to zero with the rear sight I have and no riser block.  I was looking at this front sight:

GG&G Flip-Up Front Sight with Locking Detent Gas Block Height AR-10 Steel Matte
Product #: 189457 (again a Midway USA part #)

and noticed in the reviews that it was a different height then the one I have on the gun. But it does not say whether it is higher or lower. If it was lower, it might just solve my problem. Anybody know?

For perspective only I am a former USMC marksmanship instructor and USMC competition shooter and have a pretty good idea on how to utilize an aperture sight system effectively. I am very particular on getting my rifles zeroed perfectly, but in this case have been unable to do so. However in all fairness I am getting a little long in the tooth as they say, and can readily admit there might be something I am missing here ( pun intended )

I thought it was quite possible that someone else had tried the same sight configuration and ran into the same problem and could advise me on this matter.
I like this BUIS system with my optical setup and they fold out of the way when I have the scope on the rifle, click up into place nicely, and if I could get it zeroed allow me to have 600 yd capability with the irons if the need arose.

I was also wondering what other iron sight setups some of you folks used on your rifles and what your experience with them was.

Thank you,

Dwight in Indiana

[dont_tread_on_me]

  Your front sight is your problem.It sits too high on the rail because it was intended for a picatinny gas block on an AR,which is below the flat-top on the AR.You need a front fight that is for the same plane as the rear sight.

[Dwight]

Yes that is a much more concise way of saying what I was trying to say.  :duh:Thank you for the clarity, I am often to wordy for my own good. Now that the problem is understood my question regarding the AR-10 sight I alluded to remains, or what other front sight would you recommend I swap to?
Thanks, Dwight

[Cid1911]

I would go with these. http://www.aimsurplus.com/product.aspx?item=XTMSSIGIARSHBT00

It should take care of your problem.

[Lizardman]

If you recently purchased ur front sight, then send it back to GG&G and trade it for this one....

http://www.gggaz.com/index.php?id=213&parents=38,41

Otherwise, buy this one.  It is made for mounting on the forearm on the same plane as the rear sight.

[dont_tread_on_me]

  Most manufacturers make both type.One for the gasblock mount and other for the full length hangguard type rail.The choice is yours really,it all depends on what sight picture etc. you are looking for.I'm thinking very strongly about getting these myself....
http://yankeehillmachine.com/store/product532.html
  You can get them cheaper,that was just for reference.

  Whatever you decide,just make sure you get a front sight designed for the same plane rail as the rear,if you are unsure,call the manufacturer or retailer and ask.I know MI (Midwest Industries) make them,so do Troy and many others as well,In fact I think GG&G do also.

http://www.gggaz.com/index.php?id=213&parents=38,41

[Dwight]

Thanks for all the great replies. I did not realize when I bought my current front sight that it was for a gas block that sits much lower then the plane of the upper receiver. I plan on ordering the gg&g mentioned and that should solve my problem.

[Whole Bunches]

If I wanted a little higher set that would co-witness with my Aimpoint CS, would this combo work for my XCR?

http://www.aimsurplus.com/product.aspx?item=XTComboDOA

Or to put it another way, would this combo be correct for my XCR by itself with no Aimpoint mounted?

Thanks,

[Cid1911]

I think you'd be better off going with the Troy set from the first link I posted.
Depending on what aimpoint mount you use, you should still be able to get a low 1/3 co-witness and if you use no aimpoint at all, they are about perfect to get a good cheek-weld with the XCR.

[Whole Bunches]

I think you'd be better off going with the Troy set from the first link I posted.
Depending on what aimpoint mount you use, you should still be able to get a low 1/3 co-witness and if you use no aimpoint at all, they are about perfect to get a good cheek-weld with the XCR.

Thank you very much for your help. 

[Dwight]

Just called GG&G and ordered the spring actuated front sight mentioned above. Just as a point of interest for others looking to add or upgrade their BUIS, the gentleman at GG&G said the matching rear spring actuated rear sight was on sale for 20% off. Hope that information may be of use to someone. Again thanks for all the helpful replies,
Dwight

[SINKER]

I have a set of Yankee Hills and I have been and still am VERY PLEASED with them.  They are not cheap, neither are they high dollar either.,