Sighting in issue/question with new M4

[mrbieler]

I took my new M4 out to the range today for a shake down cruise and to sight in the irons and H-1 Aimpoint. It's factory built 16" carbine.

I shot 100 rounds each of Federal XM193, AE XM193C, PMC, and Norinco yellow box non-magnetic.

I started with the irons at 50 yards with the H-1 turned off. The rifle was very low and I had to lower the front sight almost all the way down to get it to center vertically.

The rifle also shot far to the right. Windage is adjusted almost all the way left to get me towards zero. It's still a bit to the right, but I can see 1 thread left on the adjustment screw. I can get one more turn and then I'll be all the way left.

Now that I had things roughly centered at 50 and was printing respectable 3 shot groups, I turned on the H-1.

I walked the Aimpoint into the X and it's spot on at 50 and I was clanging the 200 yard iron pig with no adjustment. When I lower my head to look through the irons, the red dot is just above the post and the dot is just off to the left of the top of the post. It would probably be dead center on the post if I gave it one more click to the left, but the rear would be all the way over left at that point.

My concern is that I've got little to no windage or elevation adjust left.

I would like some thoughts on if I have an operator error issue on my hands or if I've likely got a misaligned front sight.

Anything in particular to look for?

[wake.joe]

Deleted

[kmrtnsn]

The rifle was very low and I had to lower the front sight almost all the way down to get it to center vertically.

??? Did you make adjustments before you shot the rifle?

[kmrtnsn]

Post some pics of your rifle and the front and rear sights.

[Quib]

The windage issue could possibly be;

- Canted Front Sight Base
- Improper Barrel Index

[Darkop]

I took my new M4 out to the range today for a shake down cruise and to sight in the irons and H-1 Aimpoint. It's factory built 16" carbine.

I shot 100 rounds each of Federal XM193, AE XM193C, PMC, and Norinco yellow box non-magnetic.

I started with the irons at 50 yards with the H-1 turned off. The rifle was very low and I had to lower the front sight almost all the way down to get it to center vertically.

The rifle also shot far to the right. Windage is adjusted almost all the way left to get me towards zero. It's still a bit to the right, but I can see 1 thread left on the adjustment screw. I can get one more turn and then I'll be all the way left.

Now that I had things roughly centered at 50 and was printing respectable 3 shot groups, I turned on the H-1.

I walked the Aimpoint into the X and it's spot on at 50 and I was clanging the 200 yard iron pig with no adjustment. When I lower my head to look through the irons, the red dot is just above the post and the dot is just off to the left of the top of the post. It would probably be dead center on the post if I gave it one more click to the left, but the rear would be all the way over left at that point.

My concern is that I've got little to no windage or elevation adjust left.

I would like some thoughts on if I have an operator error issue on my hands or if I've likely got a misaligned front sight.

Anything in particular to look for?


There is no Parallax in an Aimpoint scope. Therefore there is no correlation between the dot and the front sight post. If you look through the Aimpoint and then move your head around and change your cheek weld you will see the dot move around in correlation with the top of the front sight.

Sight your irons and Aimpoint independently of each other. 50 yards is a good Zero for an AR15. Make sure your rear elevation wheel is on "Z"

Good luck,

Until that day
Darkop

[mrbieler]

The rifle was very low and I had to lower the front sight almost all the way down to get it to center vertically.

??? Did you make adjustments before you shot the rifle?

No, I started with the rifle as it came out of the box.

Rear fixed BUIS is factory with no elevation adjustment.

My assumption or misunderstanding on the RDS and BUIS was that when I use the BUIS that I would/should see the dot at roughly in the same spot once they're both producing the same POI. When I use the RDS, I ignore the sights completely.

[kmrtnsn]

I looked at the DDM4 on the DD web-page and am assuming that you are using the pictured rear sight. The rear sight has a flip up/flip down setting. Big aperture for 0-300 meters, small aperture for beyond 300 meters; just like an A1 and A2. You were using the big aperture, right? Tip of the front post centered in the circle? You hadn't moved the rear sight forward or aft?

[mrbieler]

I looked at the DDM4 on the DD web-page and am assuming that you are using the pictured rear sight. The rear sight has a flip up/flip down setting. Big aperture for 0-300 meters, small aperture for beyond 300 meters; just like an A1 and A2. You were using the big aperture, right? Tip of the front post centered in the circle? You hadn't moved the read sight forward or aft?

I used the small aperture. I was under the impression that the 0~200 and 200~300 A2 aperture was for rear sights with elevation adjustment. The only changes I made to the rifle were slightly shifting the VFG position, adding the H-1, and adding a TLR-1.

If I'm mistaken on the aperture, that may give me some wiggle room on the front post and elevation, but it still leaves me with the windage issue.

Thanks for all the comments.

[mrbieler]

Not sure if this is a true indicator or not, but I took the rifle and checked level of the top of the receiver, the rear sight, and rail, and the FSB.

The bubble checked out level for everything except the FSB, which showed a definite lean to the left. :(

[mrbieler]

Updated Post:

I bought my DDM4 from RifleGear in Costa Mesa, CA. I left the shop and DD an email over the weekend discussing my concern the FSB was canted. I got a call from RifleGear this morning that DD had approved them to exchange my upper immediately.

A quick drive to the shop and we checked out my upper to confirm I wasn't huffing paint and the FSB was actually canted (it was), a replacement was checked, and installed on my rifle.

Now I get to head back out to re-zero the sights. :D

Thanks to RifleGear for prompt service and thanks to DD for setting them up for customer friendly fix.

[kmrtnsn]

Glad to hear that you worked the issue out. Kudos to Daniel Defense and to Riflegear on the quick and efficient customer service fix.