Questions/Sanity check after sighting in iron sights on new AR-15

[748rpilot]

Hey guys, I recently purchased a new AR (my first), an LMT MARS-L MLR. I equipped it with a set of Ultradyne C4 iron sights, field stripped, cleaned and lubed the rifle and then went to sight it in / zero it. Sights were torqued to 15 in/lb as specified by Ultradyne. I did not use blue loctite on the picrail screws. Ammo is PMC 223 Rem 55gr FMJ.

Sorry in advance for all the big ass pictures....

Setup & positioning
Per Ultradyne instructions, I began shooting at 25 yards. Shooting was done seated, using a stuffed backpack as a shooting bag. When setting up, I would adjust the gun on the backpack such that when I mounted the rifle, it was basically on target. Finer adjustments were made with support hand. I used a medium grip on the pistol grip, such that the gun would hold parallel to the ground if standing with the gun shouldered. I was conscious of my breathing technique and trigger finger, pulling the trigger rearward with the pad of the finger and not increasing grip in the hand & fingers. Gun was mounted such that I could view the target through the sights with my head nearly straight. As far as seating position, I setup by taking the correct standing posture, then sitting from there.

The front and rear sights were both nearly centered wrt windage adjustments.

Shooting
I began shooting 3 shot groups; my first two groups were 2.75" and 4", respectively, left of center. As I made windage adjustments to the front sight, per Ultradyne instructions, I was able to get groups to ~1.5" left of center, however, this took a significant amount of adjustment.

At this point I switched to a new target and continued shooting 3 shot groups. I felt like I had way too much windage dialed in, so I tried back it out and shot a couple groups. Sure enough, they went out further left. I continued shooting and adjusting, and ended up 1.25" left of center. However, the front sight was nearly maxed out on windage, and it took a few clicks on the rear sight as well.

By this point my hour was up, so I packed up and went to ask one of the range/gunshop guys for advice. He took a look at the sight and was like "holy shit yea that's way too much windage, that can't be right at all." So, with my permission, he centered both the front and rear sights, gave me free range time and came to watch me shoot. The first group, 2 shots were left of center by 2.5" and I shanked the last shot to 4" left of center. I dialed a few clicks on the rear, came to roughly 2" left of center. I continued making larger adjustments on the rear sight and tuning things up with the front. For example, I might go 4 clicks rear, 2 clicks front, or 2 and 1.

Finally, I was able to get basically centered up on target. However, it still took a LOT (IMO) of adjustment in both the front and rear sight. All told, I put 60 rounds through the gun.

I guess my questions are
1. This seems like a lot of windage for a brand new gun at 25 yards. Does this seem strange to anyone else?
2. Is there something I should be checking on either the gun or the sights?
3. Any other tips/tricks/advice to help me get squared away?
4. Am I just an idiot?

Thanks kindly.

ETA: Looks like my picrail screws on front and rear sights worked loose; I just re-checked them with the torque wrench. I'll apply some loctite and go shooting again. I'll leave this post up so you can laugh at me.

 

[TonyTheTiger]

This can just be the nature of the beast with rail mounted front sights. If you're using irons as a primary sighting system the front needs to be barrel mounted, or at the very least have a monolithic upper/rail system. Hopefully tightening the rear sight fixes the problem, otherwise you may need to adjust on off center mounted handguard. At 25 yards it shouldn't be nearly that bad.

 

[748rpilot]

The MARS platforms are a monolithic upper-rail system so I should be covered there. I do intend to use the irons as the primary sighting system (Primary Iron Sighting System - PISS ).

I have applied loctite to the picrail screw on the front and rear sights, and while checking the rear, noticed that the sight base does not sit flush on the rail, but is tilted left, as can be seen below:

I tried two other locations on the rail, and once tightened, all three locations showed the same issue. I tried mounting it several different times, being sure to keep the sight base centered and push down evenly on both sides, but once tightened, it always ends up like in the picture.

So, I assume either the sight base or the rail is out of spec. The front sight does not show the same issue, which leads me to believe it may be the rear sight base.

 

[TonyTheTiger]

Huh, not sure how I managed to completely miss the type of gun in the opening sentence...
Either way I'm not the least bit surprised. I've got a set of Magpul MBUS that have bounced between a dozen guns over the years and adjusting them quite a ways off center from one gun to the next is commonplace. Even with a monolithic upper I'd still recommend a barrel mounted front sight.

 

[roostercogburn98]

So, I assume either the sight base or the rail is out of spec. The front sight does not show the same issue, which leads me to believe it may be the rear sight base.

Move the front sight to the rear and vice versa. See if the rear looks crooked on the front. May be able to decide which part is out of spec like that.

 

[748rpilot]

I swapped the sights around, as @roostercogburn98 suggested, and the rear (now up front) still had some gap, whereas the front (now in the rear) did not. So, it looks like maybe it's the rear sight base.

I did try mounting the rear while it was folded down, as previously I did it while up, and for whatever reason, the gap seems to have closed up. Maybe I held it differently or pressed on it just right, but the gap seems to have closed up a bit, or just photographic tricks. I wish I could have found my feeler gauges to measure pre- and post-. I'll give it a shot again on Wednesday and see if there's any difference. Probably reach out to Ultradyne just in case.

 

[Milf Dots]

Be sure to push firmly down and FORWARD back on each sight while tightening their fasteners.

 

[Oryx]

If your front sight is mounted to a handguard and it's way off, you'll need to get that straightened out and SECURE first. Is it a free floated hand guard?

When mounting I don't see a need to push down firmly .... when tightening, the sight will settle to where the to mating surfaces align. I would push Forward, instead of backwards .... so that when the gun recoils it recoils against a solid surface. If you pull the sigh backwards in the Picatinny rail it will leave a gap that can allow the sight to move under recoil.

Never had to burn even half of that amount of ammo to sight in.

Additionally, I'd skip that Diamond target and stick with the black circle ..... are you aligning to six o'clock or center?

 

[Milf Dots]

If your front sight is mounted to a handguard and it's way off, you'll need to get that straightened out and SECURE first. Is it a free floated hand guard?

When mounting I don't see a need to push down firmly .... when tightening, the sight will settle to where the to mating surfaces align. I would push Forward, instead of backwards .... so that when the gun recoils it recoils against a solid surface. If you pull the sigh backwards in the Picatinny rail it will leave a gap that can allow the sight to move under recoil.

Never had to burn even half of that amount of ammo to sight in.

Additionally, I'd skip that Diamond target and stick with the black circle ..... are you aligning to six o'clock or center?

You are correct and I goofed. I edited my post to correct the mistake. Thnx

 

[748rpilot]

The handguard should be straight & secure, it's an LMT Monolithic Rail Platform rifle. Eyeballing, the barrel appears centered in the handguard so I think I'm OK there.

Just so I'm 100% clear, when you say push FORWARD, that's FORWARD towards the muzzle? Is that because of the force with which the BCG returns closed?

Thanks for the constructive advice.

 

[strikeeagle1]

Since wandering impact for iron sights is the topic. I just got this LaRue C-Note QD rifle iron sight. Haven't decided what real platform I might use it on yet. But, it's unique. Anyone used one yet?

 

[Milf Dots]

The handguard should be straight & secure, it's an LMT Monolithic Rail Platform rifle. Eyeballing, the barrel appears centered in the handguard so I think I'm OK there.

Just so I'm 100% clear, when you say push FORWARD, that's FORWARD towards the muzzle? Is that because of the force with which the BCG returns closed?

Thanks for the constructive advice.

Forward toward the muzzle because the first movement after the powder ignites is the rifle going backward and the optic wanting to stay where it was, which can cause the optic mounts to move forward a hair under improper installation.

 

[748rpilot]

Forward toward the muzzle because the first movement after the powder ignites is the rifle going backward and the optic wanting to stay where it was, which can cause the optic mounts to move forward a hair under improper installation.

Right, that makes sense. Appreciate it.

 

[Romeo458]

I've assembled a couple iron sight weapons and I've noticed that if I lap the face of the upper receiver I have little to no windage adjustments to make when sighting in. If you try different optics you may have laying around like a spare red dot or scope and it needs the same windage extremes it could be a receiver face that's putting a lot of torque to the barrel.

Trying a receiver mounted sight will also help in seeing if its just the front rail that is cocked off to the side. You can measure the left and right side gaps of the barrel and handguard at the front with a caliper to see if there's a tweak there too.

The only other thing I can think of is if the rail is off a degree or two from true 12 o'clock but if this is monolithic I don't think that's likely.

 

[black5.3]

Sorry if i missed it in the first post but I haven’t seen it asked yet…. You are adjusting the front/rear sight in the correct directions right??

I will also add that its kinda normal in my experience for some irons to be adjusted rather far one way or the other to get them zeroed. I would say to get your rounds within a few inches of poa and then move back to 50 yards and check/adjust then move back to 100 yards to check/adjust(depending on your desired zero range).

 

[Milf Dots]

Right, that makes sense. Appreciate it.

We should thank @Oryx- he caught my mistake!

 

[S197]

Hey guys, I recently purchased a new AR (my first), an LMT MARS-L MLR. I equipped it with a set of Ultradyne C4 iron sights, field stripped, cleaned and lubed the rifle and then went to sight it in / zero it. Sights were torqued to 15 in/lb as specified by Ultradyne. I did not use blue loctite on the picrail screws. Ammo is PMC 223 Rem 55gr FMJ.

Sorry in advance for all the big ass pictures....

Setup & positioning
Per Ultradyne instructions, I began shooting at 25 yards. Shooting was done seated, using a stuffed backpack as a shooting bag. When setting up, I would adjust the gun on the backpack such that when I mounted the rifle, it was basically on target. Finer adjustments were made with support hand. I used a medium grip on the pistol grip, such that the gun would hold parallel to the ground if standing with the gun shouldered. I was conscious of my breathing technique and trigger finger, pulling the trigger rearward with the pad of the finger and not increasing grip in the hand & fingers. Gun was mounted such that I could view the target through the sights with my head nearly straight. As far as seating position, I setup by taking the correct standing posture, then sitting from there.

The front and rear sights were both nearly centered wrt windage adjustments.

Shooting
I began shooting 3 shot groups; my first two groups were 2.75" and 4", respectively, left of center. As I made windage adjustments to the front sight, per Ultradyne instructions, I was able to get groups to ~1.5" left of center, however, this took a significant amount of adjustment.

View attachment 8110842

View attachment 8110844



At this point I switched to a new target and continued shooting 3 shot groups. I felt like I had way too much windage dialed in, so I tried back it out and shot a couple groups. Sure enough, they went out further left. I continued shooting and adjusting, and ended up 1.25" left of center. However, the front sight was nearly maxed out on windage, and it took a few clicks on the rear sight as well.

View attachment 8110846

By this point my hour was up, so I packed up and went to ask one of the range/gunshop guys for advice. He took a look at the sight and was like "holy shit yea that's way too much windage, that can't be right at all." So, with my permission, he centered both the front and rear sights, gave me free range time and came to watch me shoot. The first group, 2 shots were left of center by 2.5" and I shanked the last shot to 4" left of center. I dialed a few clicks on the rear, came to roughly 2" left of center. I continued making larger adjustments on the rear sight and tuning things up with the front. For example, I might go 4 clicks rear, 2 clicks front, or 2 and 1.

View attachment 8110851

View attachment 8110852

Finally, I was able to get basically centered up on target. However, it still took a LOT (IMO) of adjustment in both the front and rear sight. All told, I put 60 rounds through the gun.

View attachment 8110853

View attachment 8110854

I guess my questions are
1. This seems like a lot of windage for a brand new gun at 25 yards. Does this seem strange to anyone else?
2. Is there something I should be checking on either the gun or the sights?
3. Any other tips/tricks/advice to help me get squared away?
4. Am I just an idiot?

Thanks kindly.

ETA: Looks like my picrail screws on front and rear sights worked loose; I just re-checked them with the torque wrench. I'll apply some loctite and go shooting again. I'll leave this post up so you can laugh at me.

1. You stated that you held a medium grip?
2. did you make adjustments between each shot?

 

[S197]

Be sure to push firmly down and FORWARD back on each sight while tightening their fasteners.

Ive never had to do this with any rail mounted iron sights. Good sights and mounts like ultras will be very close to zero and lining up.

 

[S197]

The MARS platforms are a monolithic upper-rail system so I should be covered there. I do intend to use the irons as the primary sighting system (Primary Iron Sighting System - PISS ).

I have applied loctite to the picrail screw on the front and rear sights, and while checking the rear, noticed that the sight base does not sit flush on the rail, but is tilted left, as can be seen below:

View attachment 8110938

I tried two other locations on the rail, and once tightened, all three locations showed the same issue. I tried mounting it several different times, being sure to keep the sight base centered and push down evenly on both sides, but once tightened, it always ends up like in the picture.

So, I assume either the sight base or the rail is out of spec. The front sight does not show the same issue, which leads me to believe it may be the rear sight base.

buy a box of good ammo like FGMM
go back to the range and reset your sights to center.
get a chair to sit in and a shooting bag(not a backpack)
take at least five shots and check and post a pic of your target

 

[Oryx]

What is the final zero distance are you trying to put on the rifle? If you're ultimately going to use a 100 yd zero just get the 25 close and start moving back to 50 for a few shots and then back to 100 for final adjustments. Adjustments at such a short distance will drive you nuts. Get a longer zero and then adjust your hold for shorter distances.

A couple of suggestions as well with those sights since you mentioned you are planning on them being your primary sights ... they are designed to work in concentric circles, meaning your front aperture (hole) is centered in your rear aperture and your target centered in your front sight. Four things need to be precisely aligned, one behind the other .... your eye, rear sight, front sight and target ... if one is out of alignment your accuracy/precision will suffer. If it's a small frame AR I always try to get the most consistent check weld by touching my nose to the side of the charging handle to keep the eye consistently aligned behind the rear sight.

This is also why I mentioned to ditch the diamond targets and use your black circular targets so you can optically center it in your front sight better. It will make things easier to sort out. Conceptually, that C4 system should work , but will be limited without any aperture adjustability ... personally would use just a post.

Probably one of the things most people overlook when shooting irons is focus. Your eye can only focus on one thing at a time and most focus on the target since that is what they are trying to hit. With Irons, you need to get all 4 things aligned first and then put 100% focus on the front sight before breaking the shot. Let the target go blurry. Hard for some to get used to but your consistency and accuracy will improve.

Best of luck

 

[Milf Dots]

Ive never had to do this with any rail mounted iron sights. Good sights and mounts like ultras will be very close to zero and lining up.

That was a smart tip from a top trainer who sees on average 1500- 2000 students a year. Prior to that he was a career soldier whose job was to train SoF on weapons and tactics.

It's smart as a general practice, and even smarter when someone is having a problem with their kit.

 

[S197]

I am kind of surprised that no one has touched on his shooting capabilities with an AR. He has stated this was his first AR purchase and his shots are well spread out for only 25 yards.

 

[748rpilot]

Let me try to catch up here...

@Oryx I agree about the black target; once I switched to that target I felt like the sight picture become more clear and visually, it was much easier to align the sights and the target. The black target actually fit just near perfectly in the sights. I was holding to center, btw. When I go back, I'll shoot that style target. I definitely understand what you're saying about the alignment concepts of the C4 system, I used to shoot an archery sight that used the same system. A hollow front pin inside a circular housing, with a concentric circle mounted to the cable/roller guard, and then a peep. That is what drew me to the C4 system for the rifle, as I quite liked it and had a lot of good shooting with it on the bow.

WRT shooting distance, I'm mainly expecting to shoot between 25 and 50 yards to begin with and as I get the hang of the AR, move it out to 100 and 200 yards, although my least amount of shooting will be at 200.

I've re-installed the sights, with loctite this time, and will hit the range either tomorrow or Wednesday to give it another go. Not sure if I mentioned it previously, but when I got home from the first range trip, after making this thread, I checked the screws and they had worked loose, so I'm hoping that is/was the majority of my issue here. I'll also take some handguard to barrel measurements. If I can't get good results with different ammo and the reinstalled sights, I'll try some different irons and then check the barrel to receiver mating @Romeo458.

@S197 as to grip, what I meant was that I held a firm purchase on the pistol grip, such that in an off-hand position, I could remove my support hand and still hold the rifle basically on target, and I wasn't death-gripping. One thing I am having an issue with is keeping the wrist fully locked, but that's due to a physical injury I am rehabing. If you mean did I make sight adjustments between shots, I did not. I would shoot 3, bring the target in, adjust sights as necessary, send the target out and repeat. If you mean position/technique-wise, no, I tried to keep everything the same as I could. When I go to the range this week I'll shoot some FGMM and a couple other loads and I'll post the results. I'll see about a proper bag as well.

Of course, thanks again for your insights and ideas.

 

[Milf Dots]

Your approach to the zeroing effort appears positive, so it'll be interesting to learn what the problem is.

 

[msgriff]

snip...

@S197 as to grip, what I meant was that I held a firm purchase on the pistol grip, such that in an off-hand position, I could remove my support hand and still hold the rifle basically on target, and I wasn't death-gripping. One thing I am having an issue with is keeping the wrist fully locked, but that's due to a physical injury I am rehabing. If you mean did I make sight adjustments between shots, I did not. I would shoot 3, bring the target in, adjust sights as necessary, send the target out and repeat. If you mean position/technique-wise, no, I tried to keep everything the same as I could. When I go to the range this week I'll shoot some FGMM and a couple other loads and I'll post the results. I'll see about a proper bag as well.

Of course, thanks again for your insights and ideas.

As to your injury, you might want to consider a low or zero angle pistol grip.

 

[Oryx]

If your sights were loose, that will likely be a large part of the issue. Seems like you have a good grasp of fundamentals and things should improve.
I'm not sure what your accuracy goals are for 25yds, but FGGM likely won't show drastic improvements over standard ammo ... perhaps at your longer distances. If it were me I would try lighter bullets for short distances - 50-52gr ... I found them to be more accurate than the larger bullets out to 200 yds. Lots of excellent choices in small projectiles

 

[748rpilot]

Well, I finally got back out to the range after re-mounting and Loctite'ing the sights. POI didn't really change, which was kind of neat, although I think there is more consistency in the groups, when I didn't shank one. I did NOT adjust the sights at all, so this is the same windage setup as last time.

There is another avenue I need to check up on as well, I checked the distance between the end of the rail and the barrel, using a dial caliper's depth gauge, and got an offset to the left of roughly 0.055". I would expect it to be perfectly centered, tbh. I've talked to LMT service and they are going to have me send in the upper for measurement, so we'll see where that leads. Initially I hesitated to say anything, so as not to air dirty laundry, but it's factual, and I'm not saying anything negative about LMT.

I shot the same PMC ammo as last time, with the same setup, to minimize variables. First target is the first 3 shot group, second target is 4x 3 shot groups. I pulled a couple and I know it. Shot 40 rounds total (on additional targets) since I had to pay for an hour on the range. I also picked up some M193 that I'll try next time.

 

[S197]

You should reset your sights back to zero on both front and rear then track your shots. Also your sights at 25yards should hit 1.4” below center, as they are 200 yard sights. The sights are based on a 55grn @ 3200fps, so buy some match grade ammo for best results.

Looking at how your shots are very spread out, you need to work on the basic shooting fundamentals for an AR. If possible have someone record you while you are taking shots, you’ll be able to spot your errors.