Simple Question

There's no reasons why they shouldn't be equal in theory.

The longer sighting plane on a rifle can make them easier to sight, but not necessarily more accurate.

Simple question...not a simple answer. How far are you shooting? What are the quality of the components? What kind of ammo are you shooting? Lots of factors involved in accuracy besides just carbine vs. rifle. All things being equal (including sighting radius or quality scope), yeah, they should be equal in accuracy, theoretically.

It shouldn't. If all things are equal (quality, etc.), the only real difference should be muzzle velocity. The rifle barrel should shoot flatter at distance than the carbine barrel.

The carbine in my experience is probably going to be more accurate based on the stiffness of the barrel if all other things are equal. All you are gaining from a rifle over a carbine is velocity and potentially better bullet stabilization.

Carbines, specifically AR types wit barrels shorter than 20" and telescopic buttstocks are not something I have seen or heard of at highpower matches where scores are kept. But I am a decade out of date. Should I saw off my 28" FTR?

Maybe things have changed in the Internet era of ladders and nodes, but the Texas Warehouse Experiments found a 21.75" barrel to be most accurate for benchrest.

igotta40 said:

Let’s say, same make and model firearm, same ammo, 100 yards. One has a carbine barrel, one is a rifle. For example, AR-15 with a 14.5” and a 24”, both in caliber 5.56 NATO. Will the additional 9.5 inches of barrel prove more accurate?

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Given the same barrel quality, both lengths are capable of the same groups. At distance, the longer barrel will excel due to better velocity leading to decreased wind deflection .

One valid reason longer barrels used to be equated with greater accuracy is potential from a longer sighting radius with iron sights. Once you substitute optical sights, that becomes a non-issue.

Barrel length does not increase mechanical accuracy, but a longer heavier rifle can make it easier for the shooter to make hits at longer ranges due to stability and extra velocity, and in the case of iron sights the sight radius.

igotta40 said:

Let’s say, . . . 100 yards. . . For example, AR-15 with a 14.5” and a 24”. . . Will the additional 9.5 inches of barrel prove more accurate?

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In fact, with the same barrel profile (barrel stiffness) the shorter barrel has a slight mechanical advantage because it will flex less.

But in practical terms, no difference.

igotta40 said:

Simple question

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There are no simple questions, only incomplete answers.

They can be more accurate.

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Mechanicaly no, for the reasons mentioned above.

Practically yes, because the longer barrel will give you a higher velocity and a flatter trajectory. That makes misses from ranging errors less likely.

Depending on what type of shooting you’re doing you might not care about the flatter trajectory and want a shorter rifle for various reasons.

BSW

igotta40 said:

Let’s say, same make and model firearm, same ammo, 100 yards. One has a carbine barrel, one is a rifle. For example, AR-15 with a 14.5” and a 24”, both in caliber 5.56 NATO. Will the additional 9.5 inches of barrel prove more accurate?

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Bottom line, no.

If you're using iron sights, the shorter barrel of the carbine and the consequent shorter sighting radius may impact YOUR ability to shoot accurately, but otherwise, the short barrel should have no impact.

If you're shooting at LONG range, the lower muzzle velocity of the carbine's short barrel will result in bullet speed dropping below the speed of sound earlier, and that will affect accuracy.

What has been said is all correct and reasonable. Length of barrel (all other factors being equal) has no effect on accuracy.

Weight - which lends to steadiness of the rifle's shooting position, in any position - length of sight spacing, and other considerations may enable the shooter to greater accuracy. It rather depends on the purpose desired. For hunting deer at ranges of 200 yards or less, no practical different. For open combat, where accuracy is essentially minute of belligerent usually under 500 yards, not much difference. For 1000 yard bench rest, probably the longer barrel gun is better.

igotta40 said:

Is a carbine as accurate as a rifle?

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Depends on the carbine . . . and the rifle.