Scientific Study: Shorter barrels are more accurate!

[Beiruty]

WOW!
13.5" barrel is more accurate than 26" that is for 308 Caliber.

Each day we will learn something new:
http://www.thetruthaboutguns.com/2013/1 ... -accuracy/" onclick="window.open(this.href);return false;

[BigGuy]

[glbedd53]

I was always told that barrel length had a lot more to do with velocity than accuracy. Kinda makes sense if a longer barrel flexes more as it heats up.

[Jumping Frog]

This has been known for years and years.

[WildBill]

Based on this article I am going to get a hacksaw and cut 12 inches off the barrel of my .308!

[jimlongley]

A bunch of years ago a fellow target shooter and I benched a heavy barrel .22LR target rifle and compared it with my little light barrel Remington Nylon 66. Not a particularly scientific endeavor, but it was fun and burned gunpowder. After 25 rounds fired rather rapidly the target rifle had maintained pretty close to its original zero while the '66 had shown a great deal of displacement, first downward and then to the left and up. We did not have a decent way to measure the temperature of the barrels, so we just touched them to see if they were warm or hot. At 100 rounds each, in approximately the same amount of time, the heavy target barrel had shifted about a minute of angle (at 50 feet, not that much) and the '66 had settled in to a deflection of about an inch high and left and stayed there. We were never able to get the target barrel uncomfortably hot, while the '66 barrel was dangerously hot.

Our purpose was twofold, there had been a recent debate on our team about whether to shoot the barrel to warm it up or start cold. Our limited study did little to advance the state of the art, but we did see a marked difference between the little Nylon 66, which was quite accurate enough for taking squirrel and sitting grouse with head shots but did not retain its accuracy as the barrel heated up, and the Winchester Model 52D which would shoot through a regular match without significantly shifting its zero.

During that time frame a lot of attention was being given to "harmonically balancing" target barrels and tuning them to the "natural length" and making sure that contact points didn't place too much or too little pressure at the wrong points on the barrel.

[Wes]

One of the reasons I went with this 308 bolt action - http://remington.com/products/firearms/ ... ac-sd.aspx" onclick="window.open(this.href);return false;

Shorter, heavier barrel. It's very accurate from bench at 100 yards. I really want to take it out to one of the longer ranges.

[BigGuy]

During that time frame a lot of attention was being given to "harmonically balancing" target barrels and tuning them to the "natural length" and making sure that contact points didn't place too much or too little pressure at the wrong points on the barrel.

I'm guessing this would have been the late 80's. Probably about same time CBers would spend hours trimming their antennas to reduce SWR.

[Charles L. Cotton]

Shorter barrels are as accurate as longer barrels, all other factors being equal, up to a certain range. That's why I chose a 20" Remington PSS in .308, rather than a longer barrel version. Clint Smith did pretty much the same experiment going from a 26" barrel to an 18" barrel with a Remington 308 bolt gun. I agree with the conclusion that in practical terms (i.e. realistic engagement ranges), shorter barreled guns are as accurate as longer barreled guns. However, it must be noted that the max. range used in testing described in the article was 900 yrds, so the test results cannot be applied to longer ranges.

Velocity determines when a bullet becomes unstable causing accuracy to diminish and trajectory (bullet-drop) to increase dramatically. Once a bullet becomes sub-sonic, it begins to yaw and soon becomes unstable. Its ballistic coefficient is destroyed. Although a difference of 400 fps may not make a large difference in accuracy between guns out to 900 yrds, a 400 fps differential is hardly insignificant. (It also makes a substantial difference in terminal performance of the round!) When I took a precision rifle course, those of us using 20" barreled 308's could stay with the 26" 300 Mags out to about 800 yrds. But at 1,200 to 1,600 yrds, it was no contest. Our bullets became unstable long before they reached those targets. (I was using Federal Gold Medal Match ammo, as were most of us.) Also, as the article noted, lower bullet velocity means the round is impacted more by wind, even before a bullet becomes unstable. This too is not insignificant since "practical accuracy" involves not merely the distance to the target, but the ability of the rifleman to hit that target.

Again, rifles with short barrels are inherently as accurate as longer barreled rifles at all "practical" distances.

[My client in the range case I tried and won in September is a ballistics expert of the highest order. We discussed much of what I have included in this post and it was presented in court.]

Chas.

[mojo84]

I think up to 900 yards will suffice for most of my handiwork.

[WildBill]

The barrel length is not the only factor is accuracy. Of course the barrel twist, bullet weight, shape and velocity will determine the stability of the bullet. Probably the biggest factor is the stiffness of the barrel. When shooting a bullet, the barrel with vibrate at a certain frequency which will cause the bullet path to change. A shorter/thicker/stiffer barrel will have less vibration and at a different frequency that a longer/thinner barrel. How and where the barrel is supported [free-floating/bedding] will also effect the vibration harmonics of the barrel. Of course temperature and humidity would be a big factor if the rifle had a wooden stock. The best accuracy would come with the optimum combination of these factors.

I also have an issue with the term "outlier" when determining group size as referenced in the "Scientific Study" I am not sure of his definition, but I think it is different than the commonly accepted mathematical definition.

[Beiruty]

Intrinsic Accuracy is not the sole determining factor. BC and Velocity would counter gravity and wind drift. The higher BC and the higher Velocity would reduce "correction factors" needed correct for both g force and wind vector. As the g is fixed and it easy to accomodate, Velocity is more important for wind vector and terminal effect on intended target at given distance.

In Short:
Shooter has to define:
1) Intended target, size, mass, etc.
2) Engagement distance, 100-300 yrds, 300-500 yrds, 500 to 1,000 yrds, or 1,000yrds.
3) Select rifle
4) Select Ammo
5) Select your Optics
6) Read Distance
7) Read Wind
8) Compute Hold over and lead into the wind
9) Aim, hold your breath, 50% breath, pull trigger.

Or get a mini laser-guided kinetic missile.

[Weg]

Based on this article I am going to get a hacksaw and cut 12 inches off the barrel of my .308!

Funny you say that, I actually did it with an Indian No. 1 MK 3 in .308, Ishapores I believe they are called. Cut it down to 16.5" and re-crowned the barrel with a dremel. I did not expect much, but to my surprise the accuracy did not get any worse, still shoots about 2" groups at 50 yards. Only thing is, it is now a very loud, hard recoiling gun..... much worse than when it had it's full length barrel and full stock. It does make a good brush gun though, bolt action mag fed .308 that holds 10 rounds. Not bad for a gun I paid $70.00 for back in the 90's.

[The Annoyed Man]

WOW!
13.5" barrel is more accurate than 26" that is for 308 Caliber.

Each day we will learn something new:
http://www.thetruthaboutguns.com/2013/1 ... -accuracy/" onclick="window.open(this.href);return false;

That's not a surprise. There is a caveat however, and that is that the shorter barrel must be no less in diameter/taper than the longer barrel. A longer fatter barrel will still be more accurate than a shorter skinny barrel.