Short Barrel Accuracy With A Scope

[Blaine]

The main argument for a long v. short barrel is longer sighting plane, but, if you have a scope on the weapon, the sight plane is inside the scope and it won't make any difference (unless, of course, there is something wrong with the barrel). That fixes that (or not???)

[olyinaz]

The other argument is performance. Some chamberings suffer from incomplete powder burn and excessive muzzle blast in short barrels. .264 Win Mag or .300 RUM for example. In other cases you can enjoy light recoil and efficient powder burn while gaining performance like that of a larger chambering. A .223 out of a 26" barrel vs. a .22-250 out of a 20" for example.

My 16" .308 semi-auto is tossing out pills with not much more stink on 'em than a .30-30 out of a .24" rifle! I don't care, but it could matter to someone given different needs, so barrel length DOES matter for more than just sighting plane.



Oly

[jeepnik]

True that some cartridges won't get all the benefit from their powder charge in a short barrel. But by handloading you can mitigate that to some degree.

[AJMD429]

You are right about the 'sight radius' thing, though...

[FWiedner]

I've always been told that if the spin inparted by the barrel is sufficient to stabilize the bullet, the length of the barrel doesn't matter with regard to accuracy.

[El Chivo]

another consideration is barrel harmonics may be better with a shorter tube - being stouter, won't whip as much.

Also the bullet is out of the muzzle sooner and less subject to tremors if your follow-through isn't perfect.

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Although there is probably something to the idea of complete burn for the powder. Notice that bolt guns come in longer barrel lengths depending on the cartridge and they are not supposed to be used with iron sights at all.

[Pete44ru]

Buuuuuut........... The least bit of barrel movement while shooting will usually throw shots wider with the shorter barrel, given the same bit of movement with each length.



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[Blaine]

Buuuuuut........... The least bit of barrel movement while shooting will usually throw shots wider with the shorter barrel, given the same bit of movement with each length.



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I don't think so..... the muzzle end of the barrel will move farther the longer the barrel....

[olyinaz]

Buuuuuut........... The least bit of barrel movement while shooting will usually throw shots wider with the shorter barrel, given the same bit of movement with each length.

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I don't think so..... the muzzle end of the barrel will move farther the longer the barrel....

Longer barrels have a moment of inertia that dampens out movement more.



Oly

[Blaine]

Buuuuuut........... The least bit of barrel movement while shooting will usually throw shots wider with the shorter barrel, given the same bit of movement with each length.

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I don't think so..... the muzzle end of the barrel will move farther the longer the barrel....

Longer barrels have a moment of inertia that dampens out movement more.



Oly

Talking about man-made movement.....The arc at the barrel end is wider the longer the barrel...

[El Chivo]

Buuuuuut........... The least bit of barrel movement while shooting will usually throw shots wider with the shorter barrel, given the same bit of movement with each length.

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I don't think so..... the muzzle end of the barrel will move farther the longer the barrel....

Longer barrels have a moment of inertia that dampens out movement more.



Oly

Talking about man-made movement.....The arc at the barrel end is wider the longer the barrel...

Yes but I am really talking about time. Think about the same movement at the moment of ignition. With the shorter barrel, you've moved the rifle less by the time the bullet leaves the barrel.

This may be negated if you can hold your long-barrel steadier because of the weight, but not everyone is like that.

[Trailboss]

I think we're looking at quite a few different factors. Bullet design, bullet weight deviation, bullet velocity, bullet spin, bullet stabilization, sight radius, execution of shot. I don't think a bullet will achieve stability for long range accuracy if fired from a 1 inch barrel, though it may have the correct spin and correct velocity. However, I also don't believe a 36 inch barrel will provide more stability than a 30 inch. So what is the shortest barrel length where all factors are optimized with a diminished return at longer length.

[86er]

In experimenting with the 357 Mag and then the 360DW in a rifle I figured out some of this as it pertains to these cartridges with these tools. In 10" bbl Contender there is some unburned powder residue from the loads I tried. At 16.5" there is none that is detectable. There is a significant increase in velocity from 10"to 16.5". Moving to an 18" bbl, there is no additional residue from powder and there is an increase in velocity that averaged just 8 fps for 6 shots. Going to a 22" bbl rifle the powder is burned but the velocity actually drops off to an average of 89 fps less. Now these are different rifles, but the diameter is consistent (measured them) and the twist is the same but for the 18" that needs just 2 more inches per turn. As far as accuracy, the 16.5 " rifle does better with the same sights as the others (bead front, Williams or Lyman receiver peep on rear). We used a 20" with different sights and it would be the second most accurate. Now, with a scope in the "scout" position the 16.5" bbl holds its own as most accurate. The 20" rifle could not take a scope so was not included. The 18" barrel was second most accurate w scope in the traditional position, set on same power. The 22" rifle was least accurate even with scope. My own thoughts about the 16.5" bbl rifle is that the thick barrel and heavy frontal weight aid in its overall accuracy by less flex and more steadiness and less muzzle jump. The rifle is kind of heavy at 7 pounds considering the short barrel and short stock! I've also tweaked the fore-end and barrel band because I own that rifle. The other Leverguns were 18 and 20" but they have standard diameter barrels and weight less than the short rifle. The 22" is a break open single shot so it has altogether different characteristics that effect it's accuracy. I do think the 22" is easiest to aim quickly with the peep sights because I get a view that is about perfect, ignoring the peep hole, focused front sight and slightly blurry target. It doesn't matter with the scopes. The peep set up is easier and faster to aim than the longer barrel with the regular open sights. So, barrel length does have something to do with powder burn and velocity but not so much with accuracy. The whole characteristics of the rig make more difference in accuracy. And the sights make a big difference in how much of the potential you can get out of it. I personally emphasize balance and stock configuration as most important to me for accuracy followed by sights. This is a good, interesting question you ask and I look forward to other experiences with different calibers and rifles.

[Pete44ru]

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I luv the smell of napalm in the morning ! . . .



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[COSteve]

Buuuuuut........... The least bit of barrel movement while shooting will usually throw shots wider with the shorter barrel, given the same bit of movement with each length.



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Nope, if angular deflection is the same it doesn't matter how long the barrel is. But we digress. The OP was questioning the accuracy difference of the different barrel lengths. Assuming the charge weight and powder burn rate are optimized for the barrel length selected, shorter barrels can be more accurate because of their increased stiffness using the same bullets. However, if accuracy is desired at long ranges, then a longer barrel usually produces more accurate shots not because it's stiffer, but rather because it allows for the use of slower burning powders to push heavier bullets with higher BCs which drift less at longer ranges.