I have a Bushmaster M4 A3.  I am going to purchase an Aimpoint ML2 for it.  My problem- I HATE cowitnessing the front sight through the scope.

I have already purchased a Yankee Hill 2 piece gas block and flip up front/rear sight combo in anticipation that I will be hacking off the front sight.
secure.valinet.com/~yankeeh/products/YHM-9390.jpg
and
secure.valinet.com/~yankeeh/products/YHM-9584.jpg

Should I
A.  Proceed as planned.  Hack off the front sight and mount the two piece gas block.  Then put the Aimpoint on a low-profile mount.
or
B.  Leave the front sight alone and get a super high rise scope mount for the aimpoint even though I think they look kind of strange.

Try the high-rise mounts first.  You can return them or use them on another rifle if you still think they're weird.

Chopping the front sight assembly is a process that will be more difficult to reverse.

That's my two cents worth.
~Craig

Exactly how high do I have to go to completely clear the front sight?

Why not use a perfect co-witness height mount (common cheek-weld) and the BUIS system is out of the way when not required?

You can also remove the standard FSB without hacking it and keep FSB & taper pins on hand - no distruction required.

<ETA>  IIRC, the original distance above bore for the sight-line is around 1.55/1.57" +/_ some for manufacture and production variations.

Thanks for the advice.

I bought the LaRue mount with the ML2.  I am going to try and remove the front sight today using that link and mount the gas block and flip up sight.

Wish me luck!!

Quoted: Thanks for the advice. I bought the LaRue mount with the ML2.  I am going to try and remove the front sight today using that link and mount the gas block and flip up sight. Wish me luck!!

dont forget to post pics!

I'm going with the YHM front gas block/folding sight that's an all in one unit. I just don't understand how someone can use a dot sight or low power scope with a front sight sticking up blocking their view. Seems like you'd want a clean sight picture, I know that I do.  The folding front makes alot of sense if you'll be using optics.  

Quoted: I'm going with the YHM front gas block/folding sight that's an all in one unit. I just don't understand how someone can use a dot sight or low power scope with a front sight sticking up blocking their view. Seems like you'd want a clean sight picture, I know that I do.  The folding front makes alot of sense if you'll be using optics.  hr

Finally!  Someone that agrees with me.  

I'm sorry, but looking through this sight is confusing as hell.
http://home.earthlink.net/~roglisaj/gunsnet/eotech-dot.jpg

The Larue mount is 1.7 inches vs. 1.5 inches for ARMS, GGG and others. As a result the front sight is in the bottom 1/4 of your view. I like it better than the ARMS M68 with spacer setup on my other carbine.

Keep both eyes open.


You'll barely notice it, and it will save you alot of headache.

Why hack off the FSB.  They come off relatively easily if you take your time and use the right tools.

Quoted: Keep both eyes open. You'll barely notice it, and it will save you alot of headache.

Yes, Marksman14 is correct.  The sight pictures taken via camera can be kind of misleading because it's basically a monocular view through the sight.  When using both eyes and focusing on the target the front sight literally ghosts and disappears.

Practice using your sight properly and it will become second nature.

Some people who have tried a 1x optic w/o the front sight say they actually prefer to have the sight there.  YMMV.  

I wouldn't want the optics up high enough to keep the sights below them.  WAY too high for good cheek weld and too much arc to zero.

If I were you I'd get a flip-up rear and a mount that puts the irons in the lower 1/3 or so of the optic and then shoot it like that for a while to see if the front sight really bothers you.  Then if it does you can have the front sight replaced with a flip-up type.

BTW, I think the sight line is 2.6" above center of bore for the irons.

DRD posted these nice pics of an EOTech sight picture in the "Views through some ACOGS, ...." thread in the optics forum:



He explained that the top view is what you see when focusing on the reticle, the bottom view when focusing on the target (130 m away).

They may not match exactly what you see either since the camera's depth of field isn't necessarily the same as the human eye's.  However, they do give you a better idea of what things look like when you are using two eyes and focusing on the target rather than the EOTech.

<edited to remove duplicated pic>

Years ago, when I was a flight instructor, I was forced to the conclusion that individuals vary tremendously in how they sort out optical data. And that one set method of teaching would not work for everyone, or for even 50% of the student population. I have since been forced to the conclusion that this holds just as true for rifles as it does for aircraft. Perhaps somebody like Bartholomew Roberts who understands optics could explain why this is; although I suspect the reasons are as much psychological as they are optical.

In any event, it appears that any one individual will react to co-witnessing in one of three ways.

There are those guys who can instantly sort through almost any amount of optical clutter. They can have their front and rear iron sights right in the main sight plane of their red dot scope and never have a problem. In fact, they’ll tell you that they don’t even see the irons when they’re shooting under pressure. These guys have the best of all situations. They can go from scope to irons with effectively zero transition time.

Other guys cannot tolerate any optical interference in the scope picture without having to carefully orient each shot. Their only salvation lies in fold-down front and rear iron sights. Their transition time from scope to irons can get to be pretty lengthy, particularly when the clock is running or the bullets are flying.

The third group (the one I’m in) can operate well enough with a limited amount of extraneous stuff in the scope picture. We can either go conventional height on the scope; coupled with a fixed front and fold-down rear or in the alternative, fixed front and rear irons with the scope raised just enough to place the irons below the primary scope sight plane. This requires some transition time from scope to irons but, a lot less than the two-fold-down set up. (Side note: Not being able to get a proper cheek weld with a raised red-dot means jack squat. You have no need for a cheek weld with a zero parallax optic.)

The main thing to understand here is that nobody else’s opinion, mine included, means jack squat as to what will work best for you. The only way to know before committing to purchase/build is to beg, borrow or steal an example of each set up and try it.

Luck,

SD

I"m sure that I could "deal" with the front sight in my optics picture if I had to but why put up with it if you don't have to. That's where the folding front would come in real handy.  On a side note, the StG 57 that the Swiss used had both a front and rear folding sight set-up with no optics.  I guess they figured if the rifle wasn't being used that the sights were better off being folded down where they'd be safe.  

Quoted: Years ago, when I was a flight instructor....

hi SD,

If I were a LEO in an emergency situation, cheek weld would indeed be much less important, especially when an Aimpoint is being used as intended and in a highly dynamic environment.  However, as a senior citizen paper-puncher who elects to buy a high quality optical, I don't feel the same way.  I chose an AR15 because I can have fun with it at the range and if an emergency ever does arise, okay.  My AR is quite suitable for that too but, in reality, I'm a paper-puncher who has an Aimpoint (just in case).

Quoted: Quoted: Years ago, when I was a flight instructor.... hi SD, If I were a LEO in an emergency situation, cheek weld would indeed be much less important, especially when an Aimpoint is being used as intended and in a highly dynamic environment.  However, as a senior citizen paper-puncher who elects to buy a high quality optical, I don't feel the same way.  I chose an AR15 because I can have fun with it at the range and if an emergency ever does arise, okay.  My AR is quite suitable for that too but, in reality, I'm a paper-puncher who has an Aimpoint (just in case).

I think that applies to about 75% of us here. We do have LEO's and Military personal in our ranks but for most of us the closest thing we'll ever see that's like a fire fight will be a a milk jug filled with water at 100 yrds.    When I use my optics I just want to see optics. If they break then I'll remove them and flip up the irons and use them. With folding irons front and rear you get best of both worlds.

Apparently I didn't explain myself well. Raising the red dot scope up a bit has no effect on your ability to obtain a proper cheek weld with your irons. As far as a cheek weld when using the red dot, who cares? Assuming you have a good quality scope, head position will have no material effect on point of impact.

We OK now?

Best to all.

SD

Well, my night has been pretty shitty.

After about 200 whacks per pin, I was left with nothing more than two mushroomed heads.  I attempted to dremmel off the heads, but at that point the front sight was so damaged from my repeated hits that I decided to try and cut the motherfucker off.  This is what I am left with, which I don't feel like going any further because I will damage the barrel.

Time to find a gunsmith.

http://memimage.cardomain.com/member_img_a/208846_502_full.jpg

Ohhhhh, looks bad. I had the same problem, heat those pins up and they'll push out.

Quoted: Ohhhhh, looks bad. I had the same problem, heat those pins up and they'll push out.hr

Unfortunately one of the "pins" isn't even recognizable anymore.  I am totally screwed.

Man I feel terrible for you ASU - major frustration.  I hope you don't need to resort to the hack approach though and a Dremel can dig in and nick your barrel.  Some folks don't worry too much about that but....   Have you tried slathering it down with some penetrating oil?

<ETA> No big deal SD.  It's all part of different strokes, different folks, and I didn't explain myself too well to so....

Does the round thing that holds the handguard in place come off?  If it doesn't, I have no way of dremmeling the rear piece.

asu174,

Go to the hardware store and get some Kroil. Soak the fsb in the Kroil overnight then try removing the pins again.

Well, I ended up repairing the damage done with some JB Weld and some BBQ paint.  Then I sold it "as is" for $100.
http://memimage.cardomain.net/member_img_a/208846_510_full.jpg


After that, I took my gun over to Warren at Ammetec Arms for a new barrel.  I ended up leaving with a little more than I went there for, but I am VERY happy with my purchases.

Stainless M4 barrel with black oxide finish, A2 flash hider, Yankee Hill free floating handguard.  Coincidentally, my flip up sights, ergo grip, and Aimpoint all came in the mail on Friday too.

I'd like to go to the range tomorrow, but I have the flu.  :(  Oh well, anyhow, it was a happy ending......

http://memimage.cardomain.net/member_img_a/208846_515_full.jpg
http://memimage.cardomain.net/member_img_a/208846_516_full.jpg