[Roc Rat]

I finally got the parts together for my M4-A3 Carbine. It has a stock front sight,, the upper is an Olympic Arms,,, M3 flat top. I got a chance to fire it today and I am baffled. I got a removable rear sight, and when mounted the gun shoots two to three feet high at 100 yds. I installed my Eotec on it and I was getting 1" groups easy,,, but with the removable rear,,, no way close. It is this type,, not a GG&G but exactly like it,,,
It is way too low, causing the shots to fly high, yet there is no elevation adjustment and the front sight post would have to be up even with the front sight ears. Anybody got any ideas other that get another rear with elevation??

 

[COPE]

I don't want to rant, but run like hell from any Oly Arms flat top. They are frequently out of spec. About 3 years ago I bought a brand new Oly flat top, and quickly noticed that no sights would mount without a cant to them. I went back to the shop that I bought it from, and they said that I was the
5th person to come back with the same problem. I contacted Olympic and they were of no help. They wouldn't take the rifle back, and they wouldn't replace the defective upper. In the end, I had to buy a Rock River upper and replace it myself. Olympic Arms customer service is the pits, hopefully you won't have any troubles, but good luck if you do.

 

[Roc Rat]

The thing that I don't understand is this,, with the Eotec sighted in, its easy to get hits at 100 yds,, the rear sight lines up with the windage/dot on the Eotec, but the elevation is so far off,, like two feet high. Did you have to replace the upper receiver or the whole top end?
It would piss me off to have to do anything major to this gun,,, it runs flawlessly,, I just want to have an iron sight on it to take over if the Eotec failed.

 

[dawg180]

It has nothing to do with your flat top A43 receiver. The problem is likely witht the knockoff rear sight. A lot of the knckoff ones are Airsoft, and aren't held to any sort of specs that would allow for zeroing.

My suggestion is that you pick up another BUIS from a known quality manufacturere and give it a try.

One other probelm is that the inherent design of the MAD style sight does not allow for gross windage and elevation adjustment. I also have one of the knockoff rear MAD sights that came with a used upper I bought, and it is readily appernt that when you flip it up it tilts a bit to one side and 'leans' forward. The real MADs from GG&G are straight up with no tilt.

 

[Roc Rat]

I just checked out the Rock River site and see that an upper is not too bad,, $120,, I wouldn't need any parts as I have a complete upper now.
Is the RR upper quality,,, I don't want to get in too deep,,, its been years since I had an AR platform,, I'm so used to 7.62x51,,, this truly feels like a mouse gun,,, but its fast and accurate, the Eotec works great on it and its accurate as hell. Just the problem with the rear sight.

 

[c473]

I'm with Dawg on this one. Sounds like you have rear sight problem. There are a ton of the matech sights out there right now for around $50. They are adjustable for windage and elevation.

 

[Roc Rat]

Well I just came in from my range and I'm happy,, I removed the rear sight and used the Eotec,, like I said, it hits easy with that. I re-installed the BUIS and was using it right thru the Eotec,, did some adjusting,, I was able to bring the front up enough and am now getting good hits with the BUIS set on the ghost ring setting. Not a tack driver, but its good enough for a mouse gun. Nice and light compaired to my 7.62 guns. I got some Privi Partisan 5.56 and boy,,, quite a snappy round compaired to my handloads. Got another 400 rds coming.