Accuracy of AR15

[foob]

Hi can someone explain why AR15s on the market can achieve such high levels of accuracy?

Is it because
1. Huge market share, many companies develop variants, and the quality and tolerances of some variants are extremely tight (and expensive)

2. A mechanical/design reason, such as direct gas impingement.

I've heard people mention FALs can never be as accurate, why is that?

 

[JesseL]

IMHO, I think you're thinking about the nature of accuracy from the wrong end.

In theory any firearm should be 100% accurate, with 0 deviation from one shot to the next.

Inaccuracy is caused by the real world variations that creep in. Things like inconsistent barrel harmonics, bolt locking, powder charge, bullet construction, etc.

To build an accurate gun is simply (hah!) a matter of not introducing the things that would screw up accuracy. The design of the AR-15 is inherently not too screwed up from an accuracy standpoint. I think most of this comes from the fact that 'heart' of the rifle formed by the bolt, barrel, and barrel extension are relatively isolated from that rest of the gun during firing.

 

[foob]

So it's inherently more accurate (due to mechanical design), but with enough money and time, any rifle can be as accurate?

 

[JesseL]

Bingo.

 

[Plink]

Some designs are inherently more accurate than others. Your mention of the FAL for example. You can spend a lot of time and a lot of money and end up with an awesome FAL. But it won't outshoot a tuned AR-15 simply because of the design differences. DS Arms makes some fine, high grade FALs. Even their top of the line model turns disappointing results compared to a match tuned M1A or AR-15 though.

Gun design is a fine balancing act though. The tighter and more accurate you make a design, the less room for error there is. That's why the AK-47 is so reliable, but not very accurate. It's loosely built by design for maximum reliability. A tight AR-15 sacrifices some of that reliability unless kept very clean. The FAL is somewhere in the middle.

There's a lot more to accuracy than just tightness though. Geometry and precision of lockup, parts flex, vibration from action cycling, barrel harmonics, chamber dimensions, ammunition, sighting systems, trigger pull, fit to the shooter, etc., all play a big part. You can change some of these on most any gun and get increased performance. Sometimes, as in the AK-47 it just doesn't make a lot of difference though.

 

[Risasi]

That's just not true Plink,

I've seen some pretty accurate AK's. A friend had a Krebs which was a shade under 2" @100 yards. But he was also handpicking his ammo.


As for the notorious accuracy of the AR. Well it's true sort of. Most out of the bag AR's I've seen will easily shoot around 1.5-2.5" five shot groups @100 yards, with run of the mill ammo. Obviously if you start tweaking an AR you can get your groups REALLY small, and then you can run into some of the reliability problems which you mentioned.

Frankly the single largest factor when it comes to the accuracy game, in most cases is a combination of the user and ammo. Just getting some consistent handloads put together for a rifle can drastically reduce the size of your groups. And likewise practice will payout better than many fancy accuracy doodads ever will.

Then again you are right about the other stuff. You almost have to study each gun platform to find out what causes them to be inherently accurate/inaccurate.

 

[Eyesac]

+1

I think most of this comes from the fact that 'heart' of the rifle formed by the bolt, barrel, and barrel extension are relatively isolated from that rest of the gun during firing

 

[RockyMtnTactical]

So it's inherently more accurate (due to mechanical design), but with enough money and time, any rifle can be as accurate?

Not exactly. For a semi auto, the AR15 is inherently more accurate. It is also capable of TONS of upgrades that will improve accuracy.

Other semi autos can come close, if they are altered enough... But I don't know of one (offhand anyways) that is capable of the accuracy an AR15 is...

 

[Highmaster]

AR's are seen to be more accurate because an accurate one is easier to build than other semi-autos. Almost anyone can screw one together from quality components and have a shooter.

The design is superior for easy buitl accuracy. The free floating handguard and minimal interferance of the gas tube is what sets it apart. M1A's have bedding to contend with as well as careful installation af the gas system and the sights have to be honed in to be accurate. This is beyond most garage gun plumbers. Not to mention the fact that it is far easier to order a Geissele trigger and drop it in an AR than find a competant smith to tune a M1A trigger.

There has never been a design for semi-auto's other than the above to be used in highpower competition. AR's have taken over because they are easier to build, maintain and easier to shoot (low recoil) than M1A's. If a FAL or any other type of bottom feeder was superior it would be on the line.

 

[Slamfire]

I like Plink's answer, let me toss in another idea. I saw Remington factory data on the average accuracy of their target bolt action. It was a 700 but they gave it a different model number. The trend was, the larger the caliber, the greater the average group size. Based on that, I truly believe that the more "horsepower" a cartridge gives off, the more deflection you will see in a rifle system. And that is also a source of inaccuracy.

The AR is a .223 (most versions). The M1a and FN fire rounds that have seven times the momentum. They bend more.

 

[wanderinwalker]

Highmaster is right. To get an accurate AR, find a good barrel, install float-tube, consider job finished. (Sights, triggers, etc... those are for the shooter, they don't make the platform more inherently accurate, just easier to use.)

And I have yet to see an AR tightly fitted improving its accuracy. My Armalite rattles some when shaken, but is still X-ring accurate out as far as needed. Also, it is reliable. I haven't cleaned it in a couple of months and it's still just trucking. Spray some lube on the carrier before practice and I don't anticipate any problems.

You can spend tons of money on something else to get it to shoot like a garden-variety floated AR, or you can spend that money on said AR and learn it's ins and outs. Or you could put that money into the AR and get something that will really shoot.