Colt AR-15 A2, Excessive Windage

[Matt-CZ]

I have a new to me pre-ban Colt Sporter Target A2 rifle. It's a carry handle A2 rifle.

I am finding that it requires about 16-18 clicks of the rear sight to the right to get me on target at 100 yards. I need to do some more shooting, as I'm not a great shot, but it groups pretty far left at mechanical zero. What is considered "in spec" when it comes to windage adjustment? The Colt uses tapered pins on the FSB, so no quick adjustment there without rotating the barrel.

Is there anything I should check for? There is no obvious cant to the FSB that I can detect without any tools, but I'm not experienced with this rifle.

I am in the South Shore area, is there a AR armorer that someone would recommend that could inspect my rifle for sight/barrel alignment issues? I'm guessing Colt won't cover such an old rifle, though by my estimation the rifle was hardly fired by the previous owner(s) and appears like new.

 

[Mountain]

Usually it's the front sight that will be the problem. Maybe put the rifle upside down on a level surface- granite countertop, drafting table, etc. and see if you can notice whether or not the front site is canted a bit. The ears of the front site and 'rails' of the carry handle should more or less all sit flat. I have an old White Oak barrel that I bought slightly used. It used tapered pins but the front sight position was off, so I had to do a little more reaming to correct as best I could. I'll probably still go to a set screw front sight.

Maybe it's you? Have another person shoot it?

 

[Matt-CZ]

Usually it's the front sight that will be the problem. Maybe put the rifle upside down on a level surface- granite countertop, drafting table, etc. and see if you can notice whether or not the front site is canted a bit. The ears of the front site and 'rails' of the carry handle should more or less all sit flat. I have an old White Oak barrel that I bought slightly used. It used tapered pins but the front sight position was off, so I had to do a little more reaming to correct as best I could. I'll probably still go to a set screw front sight.

Maybe it's you? Have another person shoot it?

I'll give this a try, thanks! I would be happy if it turned out to just be bad marksmanship on my part, but I'll have to do some more shooting to figure that out.

What would you consider too many windage clicks on the rear to be acceptable? I'm not maxed out to the right, but 18 seems like a lot to me.

If it does turn out to have a slight cant, what's the recommended remedy? Armorer just loosen the barrel and reinstall? Any place you'd recommend for this kind of work?

 

[DW357]

Armorer just loosen the barrel and reinstall? Any place you'd recommend for this kind of work?

@sschevy at Northeast Arms in Peabody could help you out. Assuming that's not too far for you on the south shore.

 

[Mountain]

I'll give this a try, thanks! I would be happy if it turned out to just be bad marksmanship on my part, but I'll have to do some more shooting to figure that out.

What would you consider too many windage clicks on the rear to be acceptable? I'm not maxed out to the right, but 18 seems like a lot to me.

If it does turn out to have a slight cant, what's the recommended remedy? Armorer just loosen the barrel and reinstall? Any place you'd recommend for this kind of work?

How much of the available travel from center to right have you moved the sight? 18 seems like a lot but might depend on the sight.

Your AR barrel might move a very slight about once seated against the upper receiver, but I'd still put money on the front sight. The barrel will only fit in one position, so it will only move around based on the tolerance between it and the receiver- usually that's nil.

Depends on your mechanical skills, but loosening a barrel and re-torquing is pretty simple if you have a proper armorer's wrench and vise blocks. The armorer's wrenches sold by a NES member here on the site are top notch tools. I may order another just to have a spare, even though the one I have is holding up perfectly.

 

[smokey-seven]

I had a very early Colt AR15 (1965) that shot like a champ but the rear sight windage was way off center. t took me a while to figure out why. The upper carry handle was non Mil Spec and thus it was one of the reasons that went out as an AR15 instead of M16. The Carry handle was thicker on one side and thinner on the other, thus making the windage look like it was way off to one side when in reality it was dead center.

 

[Matt-CZ]

How much of the available travel from center to right have you moved the sight? 18 seems like a lot but might depend on the sight.

Your AR barrel might move a very slight about once seated against the upper receiver, but I'd still put money on the front sight. The barrel will only fit in one position, so it will only move around based on the tolerance between it and the receiver- usually that's nil.

Depends on your mechanical skills, but loosening a barrel and re-torquing is pretty simple if you have a proper armorer's wrench and vise blocks. The armorer's wrenches sold by a NES member here on the site are top notch tools. I may order another just to have a spare, even though the one I have is holding up perfectly.

I had a very early Colt AR15 (1965) that shot like a champ but the rear sight windage was way off center. t took me a while to figure out why. The upper carry handle was non Mil Spec and thus it was one of the reasons that went out as an AR15 instead of M16. The Carry handle was thicker on one side and thinner on the other, thus making the windage look like it was way off to one side when in reality it was dead center.

I still have a fair bit of windage adjustment left on the right side, so the rear sight is still certainly functional. I think I'm just spoiled by the driftable front sight on my M1 allowing for perfect windage zero of the rear. I think I'm being a bit too precious and just need to accept it.

I'm actually very happy with this rifle. It's practically NOS, and the little bit of shooting I've done with it has put more wear on it than the original owners. I wish it didn't have the bayo lug ground off, since it's a preban and all, but I'm not going to spend the money for a new FSB.

 

[Mountain]

Is your carry handle removeable? What Smokeyseven said if yes.

 

[Matt-CZ]

Is your carry handle removeable? What Smokeyseven said if yes.

No, it's an A2 upper. I'll take a closer look at it tonight to see if there are any obvious asymmetries.

 

[mac1911]

No, it's an A2 upper. I'll take a closer look at it tonight to see if there are any obvious asymmetries.

i work in hanover , be more than happy to check it out. Im planing a few lunch time range trips to hanson or pembroke next week also.

 

[mac1911]

No, it's an A2 upper. I'll take a closer look at it tonight to see if there are any obvious asymmetries.

So your about 9 minutes off 18 clicks 1/2 minute clicks.
Unless someone installed 1/4 moa sights?
thats not terrible considering no windage provisions up front like the M1. Just think about how much windage adjustment is there on the M1 front sight.then you have all that adjustment on the rear also.

So unless you want to move your front sight your stuck with what you have.

Do you have a barrel vice? If you can secure the barrel and see if the front sight is loose. i used a small 3/8 extension in the sight housing to give it a nudge on one of my sights. Moved about 4moa. I used wicking loctite on it. Sold it years ago so no idea how it held up.
Also look into the chamber and look to see if the feed ramps are aligned.
Next step which is easy for a preban is pull the muzzle device and swap out the Front sight base for a set scr ew style.
This one from fulton will work with out flats and with or with out pin holes.
Front Sight Base, Forged, FA Power Wedge, with Bayonet Lug, .625

Few things to look at.
Rear sight peep is square to the housing.
Take a good look at the rear sides of the sight. Is one side thicker than the other.
Front sight post square with base.
Loose barrel or loosen barrel and see if you get any movement to the right.

Now since your bayo lug is already ground you can drill and tap that flat for a set screw. Drive out the pins adjust the sight . Tighten set screw and then see how far off the barrel is to sight base holes. You could ream and fit new pins.

Did you do the mechanical zero/sight in at 25m?

Last thoughts. Your impacts are to the left correct.
So you need to move the front sight left. I might be wrong but if you try to drive the sight base pins in with a good rap with punch and hammer the taper will drive the sight base slightly to tbe left. Especially if they are a bit loose.
Takes .005" sight movement to move impact 1" at 100 yards.

 

[dw617]

Not mentioned in this thread, what ammo are you shooting out of it? The barrel is probably 1:7, might like a heavier bullet......

 

[mac1911]

Not mentioned in this thread, what ammo are you shooting out of it? The barrel is probably 1:7, might like a heavier bullet......

Wont say it does not happen but have you seen a 9moa shift in windage with ammo.
I have had some elevation changes and a few moa on windage but not excessive.
My 1/7 A2 (nra) service rifle will put 52-72 grains darn near in the black no matter the load with out much adjustment.

 

[dw617]

True, probably not that much of a shift.

 

[PatMcD]

Don't worry about it. Move your rear sight.