Does a longer barrel give better accuracy?

I may start building another AR. I want to stick with .223Rem caliber. I want this one to be a more accurate gun so, I was wondering what advantage a longer barrel might have?

I know thw answer if we're talking about shotguns, but not rifles.

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It's the same as shotguns (or handguns). Longer barrel is generally more accurate, all things else being equal. The longer the bullet is in the bore, the more speed it builds, and in the case of a rifle, gets more spin from the rifling for greater stability as well. That equates to more accurate over longer distances.

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686/M&P9 Pro/M&P15X/M&P15-22

All barrels whip as the bullet passes through the bore. The longer the barrel, the greater the displacement at the muzzle as the bullet leaves. Some barrels are stiffer than others, some are tuned better for consistency. But using a longer barrel doesn't guarantee greater accuracy, and may degrade it.

The gain in velocity doesn't correlate with accuracy either, and velocity is not necessary increased as much as you would think beyond 16" or so. You might see only 150 fps improvement from a 24" barrel compared to a 16" barrel for .223 Remington.

Does the optimal barrel length depend at all on the burn rate of the powder used? I imagine that maybe slower burning powders could make better use of the longer barrels.

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I have 3 .270 Win with different barrel lengths. All are equipped with Redfield 5-Star 4x scopes. The one with the 28 inch barrel is far more accurate than the 24 or 22 inch variants. I only use my reload ammo so I can rule out ammo differences. For long-range like antelope, it is definitely the 28 inch that I'll use.

Eliminating the effect of a longer iron sight radius, not necessarily. The bench rest crowd long ago went to shorter, fatter and stiffer barrels to reduce the effects of vibration upon group size. In general, given two barrels of the same weight, the short, fat barrel produced better groups than a longer, skinnier barrel.

The real question is: what kind of accuracy are you looking for at what range? Also, what shooting position?

For way out yonder, a longer barrel will generally give higher velocity, especially with heavy bullets. Higher velocities mean less wind drift, flatter trajectory and less bore time for your wibbles & wobbles to throw things off. The Palma match shooters generally go long (they shoot at 800, 900 & 1000 yards) as they want bullets to be supersonic way out there.

A heavier barrel can reduce the effects of your wobbles, reduce vibrations and slow heat build up that can affect groups. 20 inch .308 barrels will shoot 1000 yards accurately, they just have greater drop and your wind calls have to be better.

If it helps you, the USAMU DMR uses a 1-8 twist 20" barrel (blanks by Douglas, Hart or Krieger) HBAR profile with the portion under the handguards fluted to reduce weight. Front sight tower is located by set screws, not cross pins. Ammo is 77 gr Black Hills.

Challenge: Find a firearm that all else being equal aside from just the length of the barrel where the shorter barrel equals or exceeds the longer barrel in accuracy at the upper end of usable distance for the caliber and type of gun.

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686/M&P9 Pro/M&P15X/M&P15-22

No..........

OK, my 2 cents- All else being equal, generally a shorter barrel (say 18 - 20 inches is as accurate, or more so, than a longer barrel of the same weight. You may shoot the longer barreled gun better if using iron sights, due to the longer sighting plane. You may get more velocity with a longer barrel...

But, barrel harmonics have a definite affect on accuracy, and a shorter barrel is more stable and consistent than a longer barrel of the same weight. Take a 1 inch diameter pipe, 2 foot long, hold it by its end, and shake it. How much does it flex?. Now, try the same test with a 10 foot length of the same pipe. How much more does it flex?

If barrel length alone was the deciding factor in accuracy, most unlimited class bench rest shooters would be shooting with 50 inch or more barrels, but they don't.

A barrels longer length does not cause a bullet to spin appreciably faster - that is a function of rifling twist rate. There are advantages in a longer barrel as far as bullet drop and wind drift is concerned, as velocity is usually a little higher, but bullet drop in particular, will remain consistent no matter the barrel length, and can be figured and adjusted for as needed. Look what those guys shooting those old iron sighted sharps rifles ant silly long ranges can do...

If it were me building a new AR, and using a scope, I would go with an 18 inch, heavy profile, free floated barrel.

Quote: " Challenge: Find a firearm that all else being equal aside from just the length of the barrel where the shorter barrel equals or exceeds the longer barrel in accuracy at the upper end of usable distance for the caliber and type of gun."

Closest I can come up with is my S&W 629's. My 6 inch 629-6, with a Leupold 2x scope will print tighter groups at 100 yards than either of my 8 3/4 inch 629's with the same scope. But that alone, does not really prove anything...

Larry

WR Moore covered it well.

All I have to add, which is slightly off topic, is that a 20" barrel opens up a rifle length gas system. In my experience, the longer gas system is a little more forgiving when reloading; more tolerant of different burn rates, lighter loads, etc. which is nice when wringing out loads for accuracy.

Challenge accepted. Ruger American Rimfire, comes in a compact model with 18" barrel and a standard model with a 22" barrel. Available in .22lr, .22 WMR, or .17 HMR. The only difference between standard and compact being barrel length and stock length.

Folks are reporting the same level of accuracy with both rifles, and the difference in muzzle velocity has been negligible.

This simply isn't true.

Dennis.

This is a 2 part answer:

1. No. Within practical lengths and reasoning, the length of the barrel is one part of about 5 factors for determining absolute accuracy. But suffice to say, I hit things out to 500yds to get my marksman about 24 years ago with a 20"barrel. Conversely, I hit out to 300 with a 14.5" barrel with something like 50,000+ rounds thru it; it was a training rifle.
2. Yes. The length of the barrel plays an effect in the pressure developed in the barrel, meaning the bullet can achieve better/ max. velocity and thus carry itself on a better trajectory downrange. Barrel length WILL deliver more energy farther downrange. Short barrels leave unburned powder, or the powder burns out the barrel as the bullet is leaving- which means wasted energy. The longer barrel, when equipped with iron sights will give a better sight profile, making for better potential aligning of a target- not better accuracy, but better aiming.

Factors for absolute accuracy: 1. Bore/ rifling. The type of rifling, and the quality of the bore are paramount to absolute accuracy. If the rifling is too tight, if the rifling is not well formed, you lose accuracy. 2. Throat and leade. This is super important, because when a round first fires and the bullet starts moving, it is not on the rifling. It is in the throat of the barrel. The shorter that distance between the sides of the bullet and the rifling, the less yaw the bullet will have when it makes first contact with the threads. Conversely, when the throat gets burned up, the bullet does not seat as true and has a little cock-eyed entry into the barrel, which on the other end leads to less accurate flying. Throat erosion is more common on higher velocity charges and rounds. Anything going much over 3000FPS is starting to burn barrels. A 243 leaving a barrel at 3300FPS is an amazing thing- screamer, but the barrel life is actually about 500-900rounds. (Absolute accuracy. Don't confuse with hunting accuracy.) 3. Twist. Match the twist to the weight of the bullet. Bigger calibers will need a bit less customizing in this aspect, if bullet constructions are similar. A 30-06 with 1/10 rifling will handle most any bullet from 140-200gr. pretty equally, with the weight and powder charge of said projectile determining trajectory, but accuracy is fairly equal for most weights in a given range. With a small bullet- the weight and speed have more to do with it, as the lighter bullets tend to be of a less robust design, and with too tight a twist, they can fly wild, or tear themselves apart from the spin applied to them.
4. Bullet and charge. Bullet and charge matching mean much more to accuracy than most anything else. Some rifles just love a lot of ammo. Some are very picky, and can deliver amazing results when the right ammo is found, or made for the barrel. Also, bullet CG is very important. A longer, more stable in flight bullet will deliver better accuracy as it will handle itself in wind much better. A short sided bullet is much more likely to fly wild the further out you get. Explanation: A long bed double cab truck is slower turning, but very stable down the road. A Jeep CJ7 is squirrely and steers very quickly. Charge; some powders deliver more consistent pressure. Some deliver higher pressures. Some burn quicker, some slower. Each has its' reasons, and reloaders and bullet designers take years getting this voodoo to work for them. And then there is the guys at LAX Firing Range, who sweep ALL powders from the top of the table into a pile, and reload all ammo with the same stuff.... so one round leaves the barrel breaking the speed of light, and the next one farts and exits the barrel with all the force of a '67 VW Bug.
5. Crown. While the crown allows for a 'clean finish' as a beer afficianado would say...... I am more of the Bud Light crowd. The finish is not all it's cracked up to be, so long as there is another beer in the ice chest. I have seen rifles where the crown is jeweled and every effort was made to get just the perfect angles to allow the bullet to leave the barrel with the perfect expulsion of gases behind it so as to not disrupt the tail turbulence from the bullet, allowing better tracking.
AND THEN I shot my best ever group with a hunting rifle which has a dinged crown because the nose got bounced off a rock, and I had to scrape a shaving off the edge of the crown with a sharpening stone out in the field, maybe 200 rounds and 4 years prior. What can I say??? That rifle REALLY likes Winchester XPII ammo.

Yep. Those 5 are the cover points.

You are correct. The biggest gains of a slightly slower burning powder being given 'time' to work in a longer barrel mean the actual shot is smoother, recoil is not quite as sharp, and the bullet accelerates a little more slowly, yet still achieves max. velocity. Side bonus; barrel throats tend to last longer.

For the 223, the ideal practical length is 20". If absolute accuracy is the goal, then 22" is a slightly better option, and 24" barrel length would be most ideal for the scenario you asked about. With really quick burning powders, you might see a stagnation of barrel pressure development as the bullet is just leaving. NO; the powder will not all burn, and the bullet slow down. It happens way too fast for that. The perfect scenario is for the primer to get struck, the powder to start burning, the pressure build and throw the bullet down the barrel, and pressure would build to a peak pressure of about 55,000 ish.... as the bullet reaches a point of maybe 2" from the end of the barrel. Pressure ideally would be very consistent, from shot to shot, and yes, the pressure at the very end would be slightly higher, if the charge is built correctly. A powder which burns too slow would leave energy on the table, as it were. Bigger flame report from the barrel, and the charge behind the bullet may be still building lots of pressure, which can adversely affect the tail end of the bullet, and degrade accuracy.

It will come to bear fruit at longer distances as the longer barrel will develop more velocity which will carry further downrange energy, and better resistance to wind drift. I would be willing to say that the delivered energy at POI would be VERY different at 150yds with those particular rounds. I realize that energy delivered means more to hunting than to punching paper, so in THAT respect, the difference might be much smaller.

Conversely, the shorter barrel would need to be sighted in a bit differently, as the bullet slows over distance, it's going to drop a bit faster. Means not much if the shooter is working with the optic and corrects for this. But in the old world, were it iron sights and they were set at the same 100yds, yes POI would start to show differences.

Much else comes into play; barrel harmonics, heat, etc. so there are just SO many variables. I always look at it from the perspective of the cold rifle, first shot scenario. I hunt, and that's the shot that counts. So in all reality, a bull barrel, super special free float assemblies mean little to me. While they might have some benefit for the entire day at the range? Negligible for 95% of all shooters.

If longer barrels aren't more accurate, why then isn't everything snub nosed length? With so many advantages of shorter barrels for rifles, why are they even offered with anything over the legal minimum? (hint, it's accuracy)

There is long winded theory, and then there is reality.

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686/M&P9 Pro/M&P15X/M&P15-22

First off; I do not consider myself a long range aficionado. And I most CERTAINLY am not a bench-rat. I hunt, and shoot as a hobby secondary. I train for self defense, just o keep the rust off.
With this said, I do, and have shot well out beyond 800yds, albeit not with a lot of success. It takes a lot more work than folks realize to add those extra 2-300 yards onto their comfort level of shooting. And I have set up rifles for guys who shoot much, much farther than I can shoot.

You need to go to a shooting match, and see what the consistently winning shooters are using. There are reasons why they went to heavier barrels. There are reasons why they felt the shorter barrels work for them. For many, it's due to specific casing shapes like the WSSM, and combined with a faster burning powder, it can deliver amazing performance. Absolutely stunning. Much of what they do is useless to the average shooter, just as the abilities of Mario Andretti are lost on 95% of all drivers. Whatever he does to his car means NOTHING to the average driver, just as with long range shooters.

So people really need to weigh what their goals are, and what there expectations are. If you are looking to be good out to 500-700yds? A standard 20" barrel will give you everything you need. Don't even need the bull barrel. If you expect to group 1MOA at 700yds???? You need to open up to a lot of options and find what will deliver the mechanical side of the equation.

There is a balance between pressures delivered, harmonics, exit flow of gas pressure, heat, humidity and so many other variables. But to be perfectly fair, if a barrel is able to generate enough pressure and FPS to deliver the round, and the bullet is capable of being stabilized, then that's all the barrel is there to do. After that, its' all the other stuff; shooter, wind, etc.

There are some VERY GOOD guys who will get an amazing job done with a .357 mag with a slightly longer bullet and a barrel of only 8-10" and a good optic. Have seen more than one fella walk to the rifle line and while standing put an MOA group at 100yds from a pistol. And- not even a really spectacular pistol. So the barrel is part of the equation, but it's not the end all, be all.

What I care most about is good accuracy that does not weigh as much as a cinder block. I gotta carry that thing, plus whatever I shoot......

There are plenty of actual tests of longer vs shorter barrels.

The Truth About Guns did a test with .308. Started out with a Shilen match 26'' barrel and kept chopping it down until reaching 13''. They used several different types of ammo. Their results were that the shorter length actually did a bit better with consistent overall accuracy than longest length.

Google The Truth About Barrel Length, Muzzle Velocity and Accuracy

Some VERY good and thought provoking replies to the original post. My take would be to determine what goals you want to achieve and then study to see what others have done to reach that goal. There is more than one way to reach point B from point A. Good luck on your quest!

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Hue 68 noli me tangere

From the tests done by various magazines over the years it seems the consensus , in general, is a shorter stiffer barrel can be as or more accurate than a longer " whippy" barrel. Vibrations having something to do with it ..but there are no absolutes when it comes to firearms. Pick the length you like and work up a load that shoots. That's about all you can do.
Gary

Thanks gents. Some very good info here. Allow me to add some info that might help narrow things down even more.

This new build, should I actually get it off the ground, will be a .223Rem (or 5.56 NATO, but want to stick with Rem pressures) caliber. The max distance I intend for this will be 500 yards. To go further, I have a .308Win bolt gun. It will be used mostly off a bench or prone. I already have a couple 16" guns and one 20", but none are anything special. So, if I'm going to drop some coin on a barrel, I want to wring out the best I can for my $$.

Since I already have a 16" gun that works fine for less than 200 yards, I thought I'd build a more precision piece. Thus the question about length.


Well, I'm still learning about rifles, but for shotguns, longer does not deliver more accuracy. You see for the average shot shell, the powder is all burned by the time the ejecta reaches 22"-24" down the barrel. So, more length than that doesn't give you any advantage as far as ballistics are concerned. There are other advantages, but that's not part of this thread.

There is another aspect when it comes to shot shells; powder to ejecta mass ratio. Just because you have a long barrel doesn't mean you'll burn all the powder. The pressure built by the powder ignition and ejecta mass needs to be matched to get a complete burn. If the ejecta mass is too small, not all the powder is burned. If the mass is too large, all the powder is burned, but not effectively used. The goal would be to have the powder charge match the ejecta mass. Shotguns are not precision tools. Therefore, if this ratio is not found, it makes little difference to the performance of the shotgun. So, most shotgun guys don't care about this. However, I expect that it's something a rifle shooter would try very hard to achieve.


So, the question on my mind is, how long does it take to burn all the powder in a .223 shell? How do you find that sweet spot where the powder charge is right for a certain bullet mass?

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I'd suggest you contact one or more of the powder companies about tube length vs powder burn. If you're an NRA member (and you should be), you're entitled to one free technical question per year.

Now then, you can use a rifle length gas system on any tube over 16 inches. I'd suggest possibly 18-20 inches as a barrel length, HBAR or heavier barrel profile. There are full bull barrels available, as well as longer lengths, but you'd need a different gas block made specifically for that barrel. As a side benefit, it might also cut your time at the gym.

500 yards isn't enough to worry about the bullet staying supersonic. I've got a 26" bolt gun and it's roughly 400 fps faster than a 16 inch AR (60 gr bullets), but individual barrels will produce different results. I haven't done a comparison clocking with 75 grain bullets. [THE way to go beyond 300 yards with .223 BTW.] I would go 1-8 or 1-7 twist if you're going short tube. My 26" 1-9 stabilizes the Hornaday 75 gr HPBT (as does my 16 inch 1-9 RR barrel-at least to 150 yards), I suspect any longer bullet won't work.

If weight becomes a problem, a fluted barrel will reduce weight while maintaining superior stiffness to a barrel of the same reduced weight. IIRC, the fluting on the DMR rifle drops a full pound. But: poorly done fluting will screw up vibration patterns.

Last summer I went to a big time benchrest rifle competition with a friend that wanted to check things out. If a longer barrel is more accurate,, then all those folks there were missing the boat.

Short heavy barrels was all I remember seeing. Around the nieghborhood of 20". Don't recall seeing anything in the 26" range.

At the long range 1000 yd matches I see a lot of longer barrels, in the 26" range. I believe because of velocity, need to keep that bullet super sonic all the way out there. The longer barrel and slower burning powder helps with that.

Why do the magnum calibers usually have longer barrels than the standard calibers ? Velocity, need the barrel to burn the powder.

What is the optimum barrel length ? How much barrel do you need to burn all the powder you are using ?

If you are using iron sights the longer barrel / longer sight radius helps the shooter be more accurate,, not necessary the firearm be more accurate.

Why is a snubby less accurate ? Usually the short sight radius and the nut behind the trigger.

"Nut behind the trigger......"




MOM; he's teasing me again!!!!

Typically the shorter barrel will be more accurate, but not by much. There is however a noticeable decrease in muzzle blast and noise with a longer barrel. While the 16" AR is easier to manipulate and maneuver, I like the decrease in noise using an 18 inch barrel. I suppose if you never shoot without ear protection it would not make much difference.

Oh yeah, this will have a scope. My eyes won't let me use irons much anymore.

Why would anyone shoot without ear protection?

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I figure with my eyes and iron sights ,, a barrel needs to be about 4 or 5 foot long to be accurate.

Huh ?? what did you say ?? what the heck is 'shoot without air projection' ?

I know some hunters don't bother with hearing protection.

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That is changing... those of us who grew up hunting without ear protection are not passing that bad habit on to our kids. With the new hearing protection that amplifies sound but then cuts out when the sound reaches a certain decibel level, there is no reason to not use hearing protection while hunting.

Yeah I would never go without hearing protection. I've known guys to forgo all sorts of PPE though.

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Hunting is far different from bench shooting or plinking.

I'm not investing thousands of dollars in a hunt, hours and days of effort in a stalk, only to blow it because I could not hear a subtle noise from an animal I have been stalking, or something I might spook, causing my quarry to skip town.


And..... the places I hunt have a snake that will sometimes be polite and rattle for you. Not always loud, so it pays to listen.

I'm not a hunter, but "hearing protection" doesn't necessarily interfere with hearing. About half the states allow hunting with a can.

With the electronic protection available today, it makes no sense to go without hearing protection. Even one shot from a .223Rem or .308Win can cause permanent hearing loss.

This is especially puzzling to me for the guys that spend thousands on a hunting trip. If you're going to spend that much to bag some trophy animal, why not spend a little on hearing protection so you can hear your own story later?

Anyway, this thread is not about hearing protection except to say that is does help cut down on flinching. That in turn will increase accuracy.

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The electronic hearing protection I have (cheap Howard Leight) doesn't provide the directional hearing I would think a hunter might require.

Right, but he said...

Howard Leight hearing protection is on par with a $30 red dot; better than nothing, but not really worth having for serious use.

If you're going to spend THOUSANDS on a hunt, I would think that a few hundred for good hearing protection would be worth it, don't you?

I'm not a hunter either, but my hearing is worth more to me than any gun or hunt. As an instructor I need to be able to hear what students are doing. So, I invested in a set of SportEar electronic hearing protectors. They can actually amplify the sounds so I can hear better with them on than not. They cut off when a shot is taken. Truly remarkable product, but not cheap.

In 1920 I would understand not wearing hearing protection. With today's technology, I don't understand not wearing it at all.

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What has that got to do with directional hearing? Can you tell where sound is coming from with Sporty protector?

HL amplify sound just fine (in tandem with ear plugs) for conversation or anything else, but directional hearing is impaired.

Um, yes, of course. One device goes in each ear thus, stereo sound is maintained. Here is a pic of mine:


The only reason you'd lose directionality is if the electronic device has monaural processing. For that they would have to be linked and have only one microphone.

Actually, you should be able to tell direction even with the Howard Leight protectors. The problem with them is that they have directional microphones. So, the sounds tend to seem like they are coming from in front or behind depending on how you have them mounted on your head.

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Stereo is one thing, but being able to make a distinction where the sound is coming from up/down or 2 o'clock / 4 o'clock is quite another. If those you have there can do that that's impressive. Might consider getting them.

3am. Heavy brush up high, tunnels below. Hogs move thru almost silently. If you are getting close, they quit that grunting and all that other stuff. They go silent, and move very light on their feet. You won't hear much of anything, and when you do...... you need to often now look behind you to see their rump as they slink off.

And then there is deer hunting, and they are TWICE as silent.
I have tried some hearing protectors. They offer 5-10db reductions on idle. The deer you are looking for are only making about 1/2db of noise, so you barely even hear leaves rustle.
I have been next to artillery going off, and even with the very best of protection...... the first thing we would jokingly say is "Wanna answer that. It's still ringing...!"

Between various guns, Iron Maiden and AC/DC........ It's a miracle I can hear at all.

So long as you are not ripping rounds off all day, unprotected..... your ears will be fine for the most part. Lots of city noises emanate the frequencies which will attribute to tone deafness, which is the same kind of hearing loss associated with gunfire. You can hear one thing, but not another. If your wife speaks in the same tone as the rifle, or as a jackhammer pinging off concrete???? Is hearing loss REALLY such a loss?????

Well, I'm not an audiologist. I always thought that we can tell the direction of sound through the time different between when a sound reaches each ear. Isn't that stereophonic hearing? Maybe binaural is the right term?

Regardless of the terminology or science, with those ear plugs I can hear just like I'm not wearing anything. My own voice sounds different, but everyone else sounds normal. In fact, I hear other sounds much better if I turn them up a little. rojodiablo, all those sounds you mention would be easier to hear with these.

Every time I use them I'm amazed at how well they work. You would think that some of the noise would sneak through, but it doesn't. I can have a perfectly normal conversation and then take a shot and the shot is completely muffled. When shooting Trap, I can hear the click of the firing pin on a shotgun two stations away. I'm able to discern if they have their safety on or if it's a misfire through the sound the trigger makes depending on the malfunction.

These are custom fit so, I can't loan them to anyone. I wish I could because until you try them, you have no idea how amazing they are. The only drawback is the battery life isn't great. Think EOTech vs Aimpoint and these are EOTechs. Fortunately the batteries are inexpensive. Also, mine are much larger than they usually make them. I have difficult ear canals so, they made them fill my ear cavity to help them stay in better. Normally these are so small they aren't able to be seen unless you know what you're looking for.

Don't take my word for it, check them out for yourself: http://sportear.com/

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