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new AR shoots right

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benstt

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I recently got a Bushmaster in the classic A3 style, just like the AR15A2 but with a removable carry handle on top of a rail. It shoots about 4 inches right at 100 yards but in nice, tight groups. I'm not an expert with iron sights but I can shoot straight with my Garand and 1894. Have any of you had this problem, and how did you deal with it aside from shifting the rear sight 8 or so clicks left?
 
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Have you tried pointing left? JK I had the same problem with my mini-14 when it was new. If the groups are good it's just a matter of a simple sight adjustment. The bullet grain can have a different effect on accuracy also depending on the barrel twist rate. Have you tried different ammo? Are you using .223 or 5.56?
 
10mmLife said:
Have you tried pointing left? JK I have the same problem with my mini-14 when it was new. If the groups are good it's just a matter of a simple sight adjustment. The bullet grain can have a different effect on accuracy also depending on the barrel twist rate. Have you tried different ammo? Are you using .223 or 5.56?
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I've only put 50 rounds of Fiocchi 55 gr .223 through it. I plan to try a few brands in 55 gr 5.56 next weekend before I send it back to Bushmaster to get it fixed. In my opinion it should go straight with the rear sight centered when there isn't any wind.
 
benstt said:
I've only put 50 rounds of Fiocchi 55 gr .223 through it. I plan to try a few brands in 55 gr 5.56 next weekend before I send it back to Bushmaster to get it fixed. In my opinion it should go straight with the rear sight centered when there isn't any wind.
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What is the twist rate on the barrel? 1:8 seems to be most popular. If the groups are tight it's probably not a barrel twist conflict.
 
Perhaps the removable carrying handle is not mounted level. Make sure if it has 2 torque points, that they are done equally. If that does not work, consider taking the handle off and running a rear flip up iron sight on it. That will tell you if it is the carrying handle. Another thing to consider, how is your trigger pull? If you have too much finger on the trigger, it will pull your rounds to the right. In either case, what ever is happening will be amplified at the further distances that you shoot. Meaning the further out your target the further off your round will be.
 
I've considered the handle issue but I haven't delved into it yet. I'm pretty confident in my trigger pull. I don't have any issues with my other iron sighted rifles, and the Garand and M1A seem to have a similar rear peep front post set up.
 
benstt said:
I've considered the handle issue but I haven't delved into it yet. I'm pretty confident in my trigger pull. I don't have any issues with my other iron sighted rifles, and the Garand and M1A seem to have a similar rear peep front post set up.
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I only recommend these steps as a process of elimination. As if the carrying handle is tightened down on the rear of the handle more than the front, it could possibly send your round to the right per say. And using the A2 front sight and a flip up rear would eliminate any variable of the handle. If you are confident in your trigger pull, check your end plate and castle nut. Make sure your buttstock is straight and that it is not tilted.
 
RandomHero said:
I only recommend these steps as a process of elimination. As if the carrying handle is tightened down on the rear of the handle more than the front, it could possibly send your round to the right per say. And using the A2 front sight and a flip up rear would eliminate any variable of the handle. If you are confident in your trigger pull, check your end plate and castle nut. Make sure your buttstock is straight and that it is not tilted.
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That's all good advice. I'll explore those when I get home today. Thanks!
 
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RandomHero said:
Perhaps the removable carrying handle is not mounted level. Make sure if it has 2 torque points, that they are done equally. If that does not work, consider taking the handle off and running a rear flip up iron sight on it. That will tell you if it is the carrying handle. Another thing to consider, how is your trigger pull? If you have too much finger on the trigger, it will pull your rounds to the right. In either case, what ever is happening will be amplified at the further distances that you shoot. Meaning the further out your target the further off your round will be.
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Awesome points!👍
 
I've shot the M4/AR15 platform for the better part of 20 years in military and civilian life and I've never, ever had one that shot POA/POI with the rear sights set in the middle. The windage knob is there for just such occasions, it's only a problem if you are severely to one side or the other, indicating alignment issues with the sighting system.
 
Trigger Monkey said:
I've shot the M4/AR15 platform for the better part of 20 years in military and civilian life and I've never, ever had one that shot POA/POI with the rear sights set in the middle. The windage knob is there for just such occasions, it's only a problem if you are severely to one side or the other, indicating alignment issues with the sighting system.
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What qualifies as severely to one side? I'd think four inches off at 100 yards is pretty bad. I could see one inch, maybe two, but four is a lot. That's missing by a foot at 300.
 
Severely being the aperture is to one extreme side or the other. 8 clicks of windage adjustment is barely 1/4 of the full travel to one side or the other, not much really.
 
Be *absolutely* sure that your Mk.1 Mod.0 eyeball is well-centered behind the sights. You noted that you don't have any trouble behind two other rifles - so provided that you've tightened everything down properly and there's not some form of mechanical "cant" in the system (is the FSB actually aligned? is your rail/upper actually straight?), I'm inclined to first look at the shooter. :)

Maybe with the AR's stock, you're just not cheeking properly, consistently?
 
4 inches is not all that much to be off prior sighting in. I’ve had scopes I’ve swapped from gun to gun, going from zeroed to a foot off the paper. 4 inches @ 100yds (4 MOA, rounding) = 1/15 of one degree off perfect alignment (I think, was never good at maths). So somewhere between your eye, the front site, the rear site, the barrel and all the machining in the upper, etc, it’s not hard to think there is 1/15th of a degree in tolerance. That rear site assembly being a tiny fraction of an inch off center in machining can make up for this deviation, amongst a lot of other factors. These aren’t parts off the space shuttle, they are hunks of metal beaten, cut and ground into a certain shape, and most aspects are not made to all that tight of tolerances. The design allows for a great deal of tolerance on most components of the gun (which is why we are able to swap most parts around from different manufacturers and the things still work). The next rifle that has exactly zeroed sites (especially one with removable sites) will be my first. Crank that rear site over and have fun shooting.
 
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