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Posted: 4/19/2010 10:51:55 AM EDT
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Guys,
I'm having some issues with my new AR. Before I discribe the issues I'm going to give you some specs. BCM Bolt Carrier Group (MPI) - Auto BCMGUNFIGHTER™ Charging Handle (5.56mm/.223) w/ Mod 3 (LARGE) Latch BCM Standard 16" Mid Length (LIGHT WEIGHT) Upper Receiver Group w/ Daniel Defense LITE 12" Handguard (1/7 Twist, Mid Length, No Sight Post) Magpul CTR-M (Milspec) Stock BLACK TROY Folding Battle Sight Front with M4 sight-Black TROY Folding Battle Sight Rear-Black Magpul AFG (Angle Forward Grip) - BLACK Magpul ASAP Ambidextrous Sling Attachment Point Magpul MS2 Multi Mission Sling System - BLACK Magpul BAD Battery Assist Device Harris Bipod Model S-L 9" - 13" Swivel Mount (Mounted at the end of the 12" Rails) Took it out to the range last weekend for some BZO with irons. I made sure the sights were fermly attached to the rails and began. I'm using the POA, POI method of zeroing. I started at 25 yrds with the irons firing in slow groups of 3 shots. I was able to correct the left to right adjustment in the back quickly with just 2 clicks. However my trouble is with the front sight post. At 25 yards, I had to crank the thing all the way to the bottom of the adjustment to get 3" off the center of the target (due to hight over bore issues I thought). Shots were placed together well - including some of the bullet groupings touching. So I moved the target out to 50 yrds. However the bullet impacts ended up about 4" down from the target. Now if I understand POA, POI correctly the bullet is actually fired from an angle slightly elevated from parallel to the ground. So you get an arch with an apex around the 150yrd mark. But it seems like the sights are giving me the arch and instead the bullet is coming out flat and thus falling further the farther it goes. So my questions are: 1) Am I doing this right? 2) Why is my front sight post cranked all the way down? What can I do to fix this? The sight post appears to be in good condition other than a 1-2mm wiggle in the up positon. Is this normal for BUIS? Normal for a Troy? I'm planning on putting on a nice 2-8 power scope after I finish the rails so I'm stuck with a rear BUIS. Would a solid front BUIS be better? 3) Could my Free Floating Rails + Bipod be pushing the rails up and thus forcing me to screw down farther than I should? 4) I was using 55g Remington 223 FMJ. Impact points were circular and thus I believe the bullets are impacting correctly and not hitting in profile. Any help would be apprecated. |
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While the bipod could effect the POA vs POI the only way that is realistically going to happen is if you're pushing down on the rail system (which I doubt you're doing).
If the bullet is impacting 4" below the target at 50y it sounds like the front sight is too high. Are you using a folding front sight meant for a gas block on your rail? Did you buy them from a quality firm (i.e. one that sponsors AR15.com)? |
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While the bipod could effect the POA vs POI the only way that is realistically going to happen is if you're pushing down on the rail system (which I doubt you're doing). If the bullet is impacting 4" below the target at 50y it sounds like the front sight is too high. Are you using a folding front sight meant for a gas block on your rail? Did you buy them from a quality firm (i.e. one that sponsors AR15.com)? Its a Troy M4 BUIS for both front and back. It was bought from Midway. I had a thought. If I put the front sight at the end of the rail, instead of over the gas block, would I be impacting the sight angle? Thus forcing the front sight down farther than it should? |
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put the rifle in a vice and use a small level to level out the upper receiver.
once you know the upper receiver is level, move the level onto the rail and see if it isn't tilted upwards, move the level onto the barrel (could be tricky, i have a small level with a magnet on one edge that would probably work), and see if the barrel is level. if you're bottoming out the front sight, something is causing the front sight to sit way higher than it should be |
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Are you using the small aperature when you shoot? I'm using the only aperature available on the sight. Ref: http://www.bravocompanyusa.com/Troy-Folding-Battle-Sight-REAR-p/troy%20rear%20sight%20-%20rear.htm that sight has two apertures a small and a large. the aperture flips. the real question is whether or not you received the same-plane version or the A2 style offset. that will determine if it matters which aperture you're using |
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I would do hellbound's suggestion. If the upper and handguard/rail seem to be on the same plane, scrutenize the sights. Maybe remove the front sight and mount it next to the rear sight to see if they are on the same plane (same general height).
I had a similar problem. Had a Matech rear sight with a YHM flip up gas block front sight. Could not crank the front sight post down enough, or raise the Matech high enough to get shots close to on target at 50 yds. Replaced the Matech with a YHM rear flip sight, and everything was golden after that. My conclusion is my Matech is gacked somehow. From what I've read, BCM puts together good stuff, so I wouldn't much suspect the upper or how it was put together. Same with the DD handguard. And same for the Troy sights. But if dogs and cats can live together, I guess anything is possible. |
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Are you using the small aperature when you shoot? I'm using the only aperature available on the sight. Ref: http://www.bravocompanyusa.com/Troy-Folding-Battle-Sight-REAR-p/troy%20rear%20sight%20-%20rear.htm that sight has two apertures a small and a large. the aperture flips. the real question is whether or not you received the same-plane version or the A2 style offset. that will determine if it matters which aperture you're using Ok at this point I'm going to need some help to find the identifier. Where can you tell which one you have? I'm shooting out of the bigger aperature on the sight. |
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Are you using the small aperature when you shoot? I'm using the only aperature available on the sight. Ref: http://www.bravocompanyusa.com/Troy-Folding-Battle-Sight-REAR-p/troy%20rear%20sight%20-%20rear.htm that sight has two apertures a small and a large. the aperture flips. the real question is whether or not you received the same-plane version or the A2 style offset. that will determine if it matters which aperture you're using Ok at this point I'm going to need some help to find the identifier. Where can you tell which one you have? I'm shooting out of the bigger aperature on the sight. IIRC, the troy's are all same plane, unless you specifically ordered the offset style. the BCM link you posted is for the same-plane version |
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The DD rails are identical in terms of dimensions from the mid point to the top rail and to the bottom.
Measure the gap between the barrel and the top rail, and the same to the bottom rail. The measurements ideally should be identical, but usually are off a 64th or two. If its off by more than that, your rail isn't straight and could be causing the issue. Are you sure you are adjusting the FSP the proper direction? Sorry, but it needs to be asked. When zeroing, you should be flipping to the smaller of the two apertures. It is easier to shoot precisely with those. Scott |
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The DD rails are identical in terms of dimensions from the mid point to the top rail and to the bottom. Measure the gap between the barrel and the top rail, and the same to the bottom rail. The measurements ideally should be identical, but usually are off a 64th or two. If its off by more than that, your rail isn't straight and could be causing the issue. Are you sure you are adjusting the FSP the proper direction? Sorry, but it needs to be asked. Yeah I was planning on breaking out the calipers and doing some measurements. As for adjusting the proper direction - don't feel bad for asking. Its my first AR. I was screwing clockwise (down) to lower the FSP. |
I would start by changing the aperture. Use the smaller aperture whenever you use irons. It is much easier to be precise looking through a smaller hole than the larger one. That will help eliminate some of the "operator error". Not that anybody has a problem with that, right? 
I know that Bravo Company (great choice, btw) says on their website that 300-meter different-plane irons are available, but I did not see them on Troy's website or any other website when I googled the part number they referenced. Midway also only appears to offer the standard, so while it is possible you got the wrong sight, it would be unlikely. The same-plane backups are much more common. I would try to make sure that the problem is with the sights, and not the shooter. Take both sights off and make sure that they are installed correctly on the rifle. I'm not trying to insult your intelligence. You seem new to this particular product and I can't see the rifle, so I'm trying to think through possible issues. If you are new to AR-15 rifles in general, find someone who is more familiar and have them look the sights over to see if they are good to go, and also fire the weapon and see if their performance is the same as yours. Good luck! Again, great choice on the rifle. What lower are you using, just out of curiosity. |
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The DD rails are identical in terms of dimensions from the mid point to the top rail and to the bottom. Measure the gap between the barrel and the top rail, and the same to the bottom rail. The measurements ideally should be identical, but usually are off a 64th or two. If its off by more than that, your rail isn't straight and could be causing the issue. Are you sure you are adjusting the FSP the proper direction? Sorry, but it needs to be asked. Yeah I was planning on breaking out the calipers and doing some measurements. As for adjusting the proper direction - don't feel bad for asking. Its my first AR. I was screwing clockwise (down) to lower the FSP. Even a basic ruler will do the job, if its off enough to throw off your sight, you will see it! Check that and let us know. If the rail is nice and flat, then I would point toward the sights being the issue. As nice as the Troy's are, they have been known to have some QC issues from time to time. By chance are you going to put an optic on this rifle? Also, while it should NOT be causing the issue, shooting off the bipod will cause SOME deflection of the handguard if you're really on it. Zeroing with a sandbag is my preference, midway down the handguard. Though again, this shouldn't really be the cause. Regardless, I just read your build specs, damn you put some thought on this rifle. Its unfortunate that you're having issues, especially since you did NOT make the mistake of buying sub-par gear. Hopefully its just something simple that you're missing. |
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put the rifle in a vice and use a small level to level out the upper receiver. once you know the upper receiver is level, move the level onto the rail and see if it isn't tilted upwards, move the level onto the barrel (could be tricky, i have a small level with a magnet on one edge that would probably work), and see if the barrel is level. if you're bottoming out the front sight, something is causing the front sight to sit way higher than it should be Good point (rail may not be level). But an easier way to check would be use a long straight edge (a decent carpenters level will work) put it on the receiver and rail. If the rail is installed correctly the straight edge will lie flat along both rails, if not you'll either see the front rail drop away - or the straight edge only touches at the ends (indicating the rail is pointing up - thus raising the front sight). Of course the other option is the barrel either isn't installed right OR the hole for the barrel was drilled at an angle (we've had a few members come here with that issue). |
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I would start by changing the aperture. Use the smaller aperture whenever you use irons. It is much easier to be precise looking through a smaller hole than the larger one. That will help eliminate some of the "operator error". Not that anybody has a problem with that, right?
I know that Bravo Company (great choice, btw) says on their website that 300-meter different-plane irons are available, but I did not see them on Troy's website or any other website when I googled the part number they referenced. Midway also only appears to offer the standard, so while it is possible you got the wrong sight, it would be unlikely. The same-plane backups are much more common. I would try to make sure that the problem is with the sights, and not the shooter. Take both sights off and make sure that they are installed correctly on the rifle. I'm not trying to insult your intelligence. You seem new to this particular product and I can't see the rifle, so I'm trying to think through possible issues. If you are new to AR-15 rifles in general, find someone who is more familiar and have them look the sights over to see if they are good to go, and also fire the weapon and see if their performance is the same as yours. Good luck! Again, great choice on the rifle. What lower are you using, just out of curiosity. I'm planning on doing a couple of things once I get off work. 1) Put the two sights side by side on the rails and see how it looks. 2) Switch to the smaller aperature. 3) Check the level of my free floating system to make sure it isn't at an up angle. 4) Next time I'mat the range i'll ask around. |
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Are you using the small aperature when you shoot? I'm using the only aperature available on the sight. Ref: http://www.bravocompanyusa.com/Troy-Folding-Battle-Sight-REAR-p/troy%20rear%20sight%20-%20rear.htm that sight has two apertures a small and a large. the aperture flips. the real question is whether or not you received the same-plane version or the A2 style offset. that will determine if it matters which aperture you're using Ok at this point I'm going to need some help to find the identifier. Where can you tell which one you have? I'm shooting out of the bigger aperature on the sight. IIRC, the troy's are all same plane, unless you specifically ordered the offset style. the BCM link you posted is for the same-plane version If that's the case ALWAYS zero with the small aperture. You'll get better groups. Once you're done you can flip back to the large aperture and your group should still be centered around the same point. |
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The DD rails are identical in terms of dimensions from the mid point to the top rail and to the bottom. Measure the gap between the barrel and the top rail, and the same to the bottom rail. The measurements ideally should be identical, but usually are off a 64th or two. If its off by more than that, your rail isn't straight and could be causing the issue. Are you sure you are adjusting the FSP the proper direction? Sorry, but it needs to be asked. Yeah I was planning on breaking out the calipers and doing some measurements. As for adjusting the proper direction - don't feel bad for asking. Its my first AR. I was screwing clockwise (down) to lower the FSP. Even a basic ruler will do the job, if its off enough to throw off your sight, you will see it! Check that and let us know. If the rail is nice and flat, then I would point toward the sights being the issue. As nice as the Troy's are, they have been known to have some QC issues from time to time. By chance are you going to put an optic on this rifle? Also, while it should NOT be causing the issue, shooting off the bipod will cause SOME deflection of the handguard if you're really on it. Zeroing with a sandbag is my preference, midway down the handguard. Though again, this shouldn't really be the cause. Regardless, I just read your build specs, damn you put some thought on this rifle. Its unfortunate that you're having issues, especially since you did NOT make the mistake of buying sub-par gear. Hopefully its just something simple that you're missing. Thanks for the info and complement. Yeah I spent a ton of time researching the best items AND also how to make it People's Republic of Kalifornia legal. The level of stupid in this state is crazy. Thankfully we have a nice web site to help combat that. I'm planning on optics. I have the mount and scope. However, I didn't feel my rails were acting correctly so I didn't get to trying the scope at the range. One thing I noticed is that my scope mounts are just a little bit lose. I've got a American Defense Recon-S Quick-Release Scope Mount Picatinny-Style with 1" Rings from Midway as well. When I attached them at home they had about a 1/16th of an inch give where you could wiggle them side to side. I put a 6 sheets of tinfoil in the mounting system to fill the gap and it worked great (other than looking really crappy). I thought I might have just picked up a crapy mount. But would this be another effect of whatever is causing my iron's problem? |
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The DD rails are identical in terms of dimensions from the mid point to the top rail and to the bottom. Measure the gap between the barrel and the top rail, and the same to the bottom rail. The measurements ideally should be identical, but usually are off a 64th or two. If its off by more than that, your rail isn't straight and could be causing the issue. Are you sure you are adjusting the FSP the proper direction? Sorry, but it needs to be asked. Yeah I was planning on breaking out the calipers and doing some measurements. As for adjusting the proper direction - don't feel bad for asking. Its my first AR. I was screwing clockwise (down) to lower the FSP. Even a basic ruler will do the job, if its off enough to throw off your sight, you will see it! Check that and let us know. If the rail is nice and flat, then I would point toward the sights being the issue. As nice as the Troy's are, they have been known to have some QC issues from time to time. By chance are you going to put an optic on this rifle? Also, while it should NOT be causing the issue, shooting off the bipod will cause SOME deflection of the handguard if you're really on it. Zeroing with a sandbag is my preference, midway down the handguard. Though again, this shouldn't really be the cause. Regardless, I just read your build specs, damn you put some thought on this rifle. Its unfortunate that you're having issues, especially since you did NOT make the mistake of buying sub-par gear. Hopefully its just something simple that you're missing. Thanks for the info and complement. Yeah I spent a ton of time researching the best items AND also how to make it People's Republic of Kalifornia legal. The level of stupid in this state is crazy. Thankfully we have a nice web site to help combat that. I'm planning on optics. I have the mount and scope. However, I didn't feel my rails were acting correctly so I didn't get to trying the scope at the range. One thing I noticed is that my scope mounts are just a little bit lose. I've got a American Defense Recon-S Quick-Release Scope Mount Picatinny-Style with 1" Rings from Midway as well. When I attached them at home they had about a 1/16th of an inch give where you could wiggle them side to side. I put a 6 sheets of tinfoil in the mounting system to fill the gap and it worked great (other than looking really crappy). I thought I might have just picked up a crapy mount. But would this be another effect of whatever is causing my iron's problem? The ADM mounts are adjustable if I remember correctly? |
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The ADM mounts are adjustable if I remember correctly? yes. they are. you tighten the screw in the center of the locking bar. OP, i wished you lived on the east coast, i feel bad for you and would help get you squared away. do you have any friends with AR15s? why not post in the California Hometown forum and try to get someone local to go to the range with you and show you the ropes. |
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I believe they are adjustable. Like I said, I didn't have time to dedicate to the scope. Got a nice Nikon 2-8x. I was busy with first time safety checks and cleaning. Then I got hung up on irons. Oh well I'll be heading out to the range again later in the month.
Snap caps are coming later this week so I can practice with the shooting. I do have a boresight to help with the adjusting of the scope. I'm going to see if I can get it to help with the irons too. No, I don't have any friends who own an AR platform. My friends and family all use 10/22s and bolt action rifles. The range I go to is owned by an ex-marine. He helped my dad out with his Savage 22-250. He can probably give me some assistance too. |
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Well I went home and did some checking.
1) Was the front sight post firmly mounted and completely pushed down as far as it could? Check 2) Was I using the larger or smaller aperature? Larger 3) How did the sights compare. I put them one after the other on the rails. The front sight is obviously shorter than small aperature - by about a 1/8th of an inch with my setting I had a the range. I put it back to the neutral position and they looked level. Check 4) I broke out the straight edge and looked at the rails. There are 6 bolts from the Upper to the FF system. There were all on tight. There didn't appear to be any sort of angle that was noticable. So for the next time I go to the range I'll be using the smaller aperature. I put my laser boresight in and checked my irons. At around 20 yrds the boresight was 3" (give or take) lower than the irons were pointing. It looks like it could be operator error combined with maybe some bad sights. If I was to have to reinvest in sights, are there anything better than Troys? I'd love to have a rear elevation adjustment. But I also have a scope and it won't work unless the rear iron is a BUIS. Should I consider a fixed front? |
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Well I went home and did some checking. 1) Was the front sight post firmly mounted and completely pushed down as far as it could? Check 2) Was I using the larger or smaller aperature? Larger 3) How did the sights compare. I put them one after the other on the rails. The front sight is obviously shorter than small aperature - by about a 1/8th of an inch with my setting I had a the range. I put it back to the neutral position and they looked level. Check 4) I broke out the straight edge and looked at the rails. There are 6 bolts from the Upper to the FF system. There were all on tight. There didn't appear to be any sort of angle that was noticable. So for the next time I go to the range I'll be using the smaller aperature. I put my laser boresight in and checked my irons. At around 20 yrds the boresight was 3" (give or take) lower than the irons were pointing. It looks like it could be operator error combined with maybe some bad sights. If I was to have to reinvest in sights, are there anything better than Troys? I'd love to have a rear elevation adjustment. But I also have a scope and it won't work unless the rear iron is a BUIS. Should I consider a fixed front? can you explain this? how is the front sight "shorter" than the small aperture? do you mean relative to the large aperture? if there is a difference between small and large aperture, then you should zero with the small and that would account for your 3" low drop what do you mean by "neutral position"? for a 50yd/200m zero, you will be around 1.5" low at 25yd. |
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With respect to Hellbound, I'm not sure I follow his logic.
If the rifle is perfectly level, the sights by default will not be on the same level because bullets are fired in a parabolic arch relative to the target, intersecting POA during their arch. The front sight has to be lower than the rear aperture relative to the bore so that sight picture can be maintained when shooting at any kind of distance. GutPunch, a) Please post pics of your rifle. b) Next time you are out at the range, fire again from a sandbag with the small aperature and also have another shooter use the rifle as well. |
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A fixed front sight would not be my first choice if you're going to run a scope on the rifle. I have a setup similar to yours, and I bought a set of Troys just for that reason. When I'm using my aimpoint, I keep the front sight flipped up. When my scope + Larue mount goes on, the sight goes down to keep it out of my FOV through the reticle. If you're convinced it's the sights (which is certainly possible) you can send them back to midway and order another set from another vendor like BC, or go with something different like Magpul sights. You also might try the LMT fixed rear sight. It has the elevation adjustment you're looking for, but you will have to live with taking it on and off to use the scope, or get something like a red dot and use it in co-witness.
What is the intended use for the rifle? Three-gun? Practical carbine/Home defense? Range toy? |
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With respect to Hellbound, I'm not sure I follow his logic. If the rifle is perfectly level, the sights by default will not be on the same level because bullets are fired in a parabolic arch relative to the target, intersecting POA during their arch. The front sight has to be lower than the rear aperture relative to the bore so that sight picture can be maintained when shooting at any kind of distance. GutPunch, a) Please post pics of your rifle. b) Next time you are out at the range, fire again from a sandbag with the small aperature and also have another shooter use the rifle as well. I'll try and take pics tonight. It might be until the end of the month until I get back out there. Intended use is for home defense and bench rest shooting. Its not that hard to add/remove scope + harris bipod. |
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With respect to Hellbound, I'm not sure I follow his logic. If the rifle is perfectly level, the sights by default will not be on the same level because bullets are fired in a parabolic arch relative to the target, intersecting POA during their arch. The front sight has to be lower than the rear aperture relative to the bore so that sight picture can be maintained when shooting at any kind of distance. GutPunch, a) Please post pics of your rifle. b) Next time you are out at the range, fire again from a sandbag with the small aperature and also have another shooter use the rifle as well. i wasn't talking about the sights. not once did i even mention the sights in my post about the level. what i was checking for was the rail not being level with the upper causing a HUGE difference in the sights which would cause the front sight to run out of elevation adjustment, same for the barrel. |
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With the gun on a level plain, from the hole generated from the small aperature to the top of the FSP there was between an 1/8 and 1/16th of an inch drop in elevation. Neutral position was how it came out of the box. Hellbound, You responded to this post that he has dual-plane apertures, which does not equate to me. I'm not saying you're wrong, I'm just saying that I don't understand. |
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With the gun on a level plain, from the hole generated from the small aperature to the top of the FSP there was between an 1/8 and 1/16th of an inch drop in elevation. Neutral position was how it came out of the box. Hellbound, You responded to this post that he has dual-plane apertures, which does not equate to me. I'm not saying you're wrong, I'm just saying that I don't understand. i'm not understanding him 100% either, what i am ASSuming is he means there is 1/8-1/16 delta between the small hole and the large hole... i'm just trying to help the poor guy out, he really needs to go into the hometown forum and find a california AR buddy to go with him to the range |
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With the gun on a level plain, from the hole generated from the small aperature to the top of the FSP there was between an 1/8 and 1/16th of an inch drop in elevation. Neutral position was how it came out of the box. Hellbound, You responded to this post that he has dual-plane apertures, which does not equate to me. I'm not saying you're wrong, I'm just saying that I don't understand. i'm not understanding him 100% either, what i am ASSuming is he means there is 1/8-1/16 delta between the small hole and the large hole... i'm just trying to help the poor guy out, he really needs to go into the hometown forum and find a california AR buddy to go with him to the range Correct. At the lowest the FSP can go down, it is about 1/8 to 1/16 of an inch LOWER than the aperature of the small sight. Given this info I think the sights may be correct. It might be I just don't know what the hell I'm doing.  I really need to head back with small sight and give it another shot.
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