Sighting AR - am i chasing my tail?

ochmude said:
Something like this, a simple lack of consistency between shot strings, is all I can figure. I feel the most likely answer is that the OP believes he's shooting the same point of aim each time, but his natural point of aim is in fact shifting. Either that or his rifle is only capable of 12 MOA, lol.
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If it is a palmetto PTAC special with an ainpoint that's doable to have 12moa.
 
mac1911 said:
That's impressive , what ammo and which PTAC models
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16" flat top upper and a 12" flat top upper. I'm shooting 55gr reloads. Hornady tips with 27.1gr of 4320 in mixed brass. Basically dunk the brass and fill to top of rim, crunch bullet in.

Both barrels are 1:7. It's the only twist I buy for 5.56
 
xtry51 said:
16" flat top upper and a 12" flat top upper. I'm shooting 55gr reloads. Hornady tips with 27.1gr of 4320 in mixed brass. Basically dunk the brass and fill to top of rim, crunch bullet in.

Both barrels are 1:7. It's the only twist I buy for 5.56
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If your getting 1moa with ptac and slap together reloads your doing very well or extremely lucky. You could clean house at the nationals

I was at the drug store and found a new mag on the shelf.
ARifleman.
They had some test on some of the new rifles....not many got to 1moa average.
 
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xtry51 said:
I have yet to find an AR that doesn't shoot MOA or better with reloads.
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Reloads can be tailored to specific rifles. That's beyond the OPs question. If you apply the optimum charge weight system you will see some poi shifts just with in a few grains of powder.

I,think we need to think like the op 1 rifle many brands of ammo.
My standard A2 I have was "zeroed " @ 25 meters with M855 (ppu brand and its the best of the m855 I have and the most) this "zero " is marked with paint on windage and elevation it's my base line.

If I shoot other ammo it will be off some. As will my zero depending on my eyes that day.
 
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mac1911 said:
Reloads can be tailored to specific rifles. That's beyond the OPs question. If you apply the optimum charge weight system you will see some poi shifts just with in a few grains of powder.

I,think we need to think like the op 1 rifle many brands of ammo.
My standard A2 I have was "zeroed " @ 25 meters with M855 (ppu brand and its the best of the m855 I have and the most) this "zero " is marked with paint on windage and elevation it's my base line.

If I shoot other ammo it will be off some. As will my zero depending on my eyes that day.
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Of course you would see shifts, but I'm talking group sizes.

I'm 99% sure you can take that 27.1gr 4320 load with Hornady 55gr heads and shoot sub 2moa groups with any serviceable AR that passes a throat and bore check.

Much in the same way you can buy 77gr Black Hills and it shoots amazing out of any rifle.
 
Mixing ammo doesn't help, but at 50 yards it shouldn't matter. At that range, bullet drop is negligible as is the bullet's behavior in wind. All that matters is the line of sight of the optic relative to the barrel. If you are hitting where you aim with any ammo at all, then you probably will have very nearly the same impact point with just about any other load. Your group size may vary from one load to another, but your impact point (the center any given group) should not be materially different at 50 yards if you change ammo. Hence, the ammo is almost certainly not the issue. Groups at 50 yards from a bench should be a few inches wide at most with just about any load. Otherwise, the issue is guaranteed to be shooter related (not breaking the shot when the sights/dot are aligned with the target) or something on the gun is loose.
 
xtry51 said:
Of course you would see shifts, but I'm talking group sizes.

I'm 99% sure you can take that 27.1gr 4320 load with Hornady 55gr heads and shoot sub 2moa groups with any serviceable AR that passes a throat and bore check.

Much in the same way you can buy 77gr Black Hills and it shoots amazing out of any rifle.
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So we need the OP to get to sub 2" groups and then see where his poi goes with different ammo?
 
xtry51 said:
I have yet to find an AR that doesn't shoot MOA or better with reloads.
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Sadly i have a piston gun that will not shoot MOA regardless of what you put in it. Barrel only has a few hundred rounds through it. When it had a handguard i could not keep all rounds on an 8-1/2 x 11 sheet of paper at 100 yards with Federal bulk ammo (even took the 18x scope off one of my bolt guns, didnt help).

After floating the barrel its a 3-4 MOA gun with 52-55gr loads and a 2 MOA gun (10 shot groups) with 75gr match bullets. It has harmonic issues, and will certainly be my last piston gun.

The cleanliness is awesome, the accuracy is a deal breaker. Just ordered a DI upper, will probably keep the piston one for screwing around, and some club 3-gun matches where 2 MOA works just fine.

economist said:
Mixing ammo doesn't help, but at 50 yards it shouldn't matter. At that range, bullet drop is negligible as is the bullet's behavior in wind. All that matters is the line of sight of the optic relative to the barrel. If you are hitting where you aim with any ammo at all, then you probably will have very nearly the same impact point with just about any other load.
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You will see slight variations, but not 12 MOA.

55gr VMAX bullets for example fly 1 MOA to the right of almost any other bullet in my two .223s.

Sometimes you'll see a few MOA shift with the same bullet just by changing powder volume or powder type, but nothing like the OP is describing.

I'm thinking loose or faulty component somewhere in the setup.
 
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xtry51 said:
Dude, that blows on the piston gun.
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Yep. Below is 52gr BTHP Match on 25gr of H335 @ 100 Yards.

Same load out of my bolt gun is sub MOA as many times as i care to pull the trigger.

75 GR loads will keep within a 2" orange bull, but for whatever reason this upper only likes the heavy bullets (it is a 1:7)


20150725_143657.jpg
 
Hoon said:
Yep. Below is 52gr BTHP Match on 25gr of H335 @ 100 Yards.

Same load out of my bolt gun is sub MOA as many times as i care to pull the trigger.

75 GR loads will keep within a 2" orange bull, but for whatever reason this upper only likes the heavy bullets (it is a 1:7)


View attachment 152039
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Jesus. What kind of piston upper is it? I would have returned that thing.
 
Hoon said:
55gr VMAX bullets for example fly 1 MOA to the right of almost any other bullet in my two .223s.

Sometimes you'll see a few MOA shift with the same bullet just by changing powder volume or powder type, but nothing like the OP is describing.

I'm thinking loose or faulty component somewhere in the setup.
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Agree. My point is that most people shooting from a bench with a red dot will not notice even a 1/2 inch (1MOA) group shift at 50 yards. For 50 yards and zeroed, just about any ammo will be perceived as hitting the same place unless the shooter is very methodical (large groups, good center identification) and able to aim precisely (good shooter and/or optic with zoom, and benched/prone shooting). If I'm shooting my scoped AR with Larue upper and target ammo I absolutely would notice 1MOA at 50 yards. But with an aimpoint on a typical upper with bulk ammo I bet it would take me a few large groups to see it and that's if I'm being careful.
 
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