If barrel length does not affect accuracy

Barrel length does
Longer barrels support the round so it's more stable

 

A couple inches won't make a lot of difference but 16" is a whole new ball game. You can't really compare them.

 

I read an article years ago in one of the shooting rags that took a rifle barrel chambered in a pistol caliber (.44 mag?) and shot it while cutting an inch off and re-crowning the muzzle and shooting again etc. The net result was that the accuracy of the barrel did not fall off until they got down to around 4 or 5 inches in length. Obviously velocity dropped but not the accuracy. Interesting test.

 

I believe I remember the article that 410 mentioned...or at least one like it. Late 70s or early 80s American Rifleman. Back when they had real tech articles and not random shill pieces for the latest gadgets.
I believe it was a long-barrel Virginian Dragoon .44Mag and they just gradually bobbed it into a snubnose while documenting velocity and accuracy from a Ransom Rest. Barrel length wasn't a real big factor until the barrel got really short.

Another thing you might see affecting accuracy is barrel harmonics. A load that falls into a 24" barrel's sweet spot might group worse if you chopped the same barrel to 20". But it might fall into another harmonic sweet spot when you reach 18" too. That is one of the real unpredictable parts of tuning a load.

As for barrel length...
On an iron-sighted gun you'll less accuracy as the sight plane gets shorter. The induced sighting error becomes greater if the sight radius shrinks but the range to target stays the same.
On an optical sighted gun that sighting error really doesn't factor in.

 

Only to a certain extent.
Once the bullet has reached it's ideal speed, usually in the first few inches of the tube, it has reached it's optimum stability. After that, it doesn't matter if the bullet is in the barrel for another 2", 10", or 40"...at least until the friction drags the velocity back down into an unstable range again.

 

Agreed. To that end, I once saw a test from a Ransom Rest on a 2" snub S&W 36 that put all 5 shots into a 2" circle at 25 yds. And that's factory ammo, so to say a snub can't be "accurate" is incorrect.
The real problem in most firearms like this are rudimentary sights with very short radius of the sighting plane. The shooter simply can't get a 'fine' sight picture.

 

That was the test that I saw also. If you have doubts as to the accuracy of a snubie, then you should watch Jerry Michalek, or Bob Munden, shoot 8" ballons at 200 + yards!

As al45ac stated: "The real problem in most firearms like this are rudimentary sights with very short radius of the sighting plane. The shooter simply can't get a 'fine' sight picture".

 

all barrel length effects is velocity produced from the powder charge.

If there are sights fixed to the barrel then it will effect sight radius, which can effect accuracy, but its more of a shooters ability to obtain a fine sight picture than it is the inherent accuracy of the barrel its self.

shorter barrels are actually more stable then longer barrels and vibration effects them less because they are more ridged.

Comparing a .357 snubbie to a .357 levergun is an unfair comparison not because the barrel is longer. but because its possible to get a more stable rest on the rifle because there is a buttstock and a fore end. Clamped into a machine rest that simply cannot move accuracy between the 2" barrel and the 18" barrel would be negligible, with the snubby rounds hitting lower on the target due to velocity loss as a result of the short barrel.

Barrel length is a paramount consideration when setting a weapon up for long range. Obviously handguns should not be considered long range weapons because of their short barrels. And most of the cartridges chambered in handguns do not have the ballistic efficiency to reach out much beyond 200 yds with suitable accuracy.

As a general rule rifle barrels 22" and longer will effectively engage targets 500 yds and further.. Carbine barrels 20" and shorter should he held to ranges out to 500 yds. Again not for accuracy purposes, but for power. due to the lesser velocity of the shorter barrel.

There are certain exceptions to this generalization.

 

There are many variable that affect accuracy, so you can only make a barrel length comparison on accuracy if that is the only variable that changes. In other words, you can't compare a revolver against lever action rifle. Too many variables are being changed.

But if you took a long barrel on say a revolver, and cut off an inch and compared accuracy, then another inch and compared accuracy and kept going till only two inches of barrel was left the accuracy would not change too much. At very short barrel length accuracy may suffer because the round may not engage the rifling long enough to get the spin fully up to speed resulting in an unstable round. But otherwise the accuracy would not suffer. Muzzle velocity would certainly suffer with shorter barrel length.

 

For the most part, barrel length (regular barrel, not the 20lb bull barrels) affects distance. If you have 2 identical style guns, say single shots, for simplicity, one is a 2" pistol and the other a 16" carbine, both are in a gun holder and they fire .38spl rounds, the one that has the 2" barrel would drop quicker (say 25 yards) than the one that is 16" (say it drops at 100 yards). Both are held pretty tight, but the one with the longer barrel would go further.

Accuracy is determined by the way the shooter handles the gun and the physics of the gun and barrel. Which is why a stock mini-14 shoots as well as a PPS-43. Ya, I went there .

 

Inquirin minds are curious about these exeptions.

 

Ok.. A 20" barreled .300 Winmag would be on the same long range plane as a 26" .30-06. because of the magnum performance of the larger round.

A 20" .22-250 would have similar ballistic performance as a 26" .223. again due to the performance of the larger round.

A 20" .240 Weatherby magnum would be in the same ballistic wheelhouse as a 26" .243 win.

etc, etc, etc..

 

hmm ... well, I have 4 pistols. An old top break .32 S&W cartridge US Revolver pistol - 3" barrel, my trusty .45 - 5" barrel, my .38 special revolver - 4" barrel and the little Italian .25 with a 2" barrel. At 25 yards I can fire any of these in a 1 to 1.5 inch group. My only rifle is my 30-30 Marlin lever action - at 50 yards without the scope I sent the very first 6 bullets I fired with it to the exact same spot. I was using a piece of wood as my target and I had trouble telling what bullet could of gone off the spot that I put on it with a marker pen. Every bullet was spot on with one of them having a very small deflection to the top left of the spot. I don't really count my shotgun when it comes to accuracy since the shot spreads over distance even at full choke.

Barrel length does affect stability in flight of the projectile over distance, but the ability of the person shooting it has far more effect. I dropped a dear last fall at about 250 yards with my Marlin 30-30 (wife and I still have meat to eat in the freezer) - granted, I do have a scope on it now. I quite likely could have made that same shot without the scope. However, I use the extra technology (the scope) so that my food won't have to suffer too much as it dies. At 250 yards it was a heart shot.