Barrel length and accuracy ?

[GetReel]

What kinda accuracy can a guy expect from a 16" or 18" barrel on a .308? Christensen Arms barrel.
I understand it will burn more powder and have higher velocities with a longer barrel but I want the shortest/lightest I can get away with. I can't foresee it being more than a 300-400 yrd gun

 

[FEENIX]

The "NUT" behind the trigger remains one of the biggest factor in accuracy. gun)

 

[CB11WYO]

The "NUT" behind the trigger remains one of the biggest factor in accuracy. gun)

I like reading your posts FEENIX

GetReel...

A shorter barrel will be subject to less vibration/harmonic inconsistency than a long barrel of the same contour. So in theory it would have more accuracy potential, bearing in mind FEENIX's comment... Adding to a barrels diameter or contour will also help minimize vibrations. I say potential because there are many long skinny barrels that shoot just fine.

I'm toying with the idea right now of building a .22 cal varmint gun with a 16" straight cylinder (or close to it) for these same reasons. Keep it short for ease of use but heavy contour for accuracy potential.

 

[el matador]

Quite a few AR-10's out there running 16" barrels. If you lean toward lighter bullets you will maximize the efficiency of the short barrel. 168's might be a good compromise between efficiency and good BC.

I have no experience with Christensen Arms but most good quality tubes will at least get you in the neighborhood of 1/2 moa with hand loads.

 

[Trickymissfit]

I like reading your posts FEENIX

GetReel...

A shorter barrel will be subject to less vibration/harmonic inconsistency than a long barrel of the same contour. So in theory it would have more accuracy potential, bearing in mind FEENIX's comment... Adding to a barrels diameter or contour will also help minimize vibrations. I say potential because there are many long skinny barrels that shoot just fine.

I'm toying with the idea right now of building a .22 cal varmint gun with a 16" straight cylinder (or close to it) for these same reasons. Keep it short for ease of use but heavy contour for accuracy potential.

Dan Lilja once said that with a #7 contour a 21" barrel was 2.75 stiffer than a standard 26" barrel. I didn't believe him! I did my own tests and found he comments to ring true.

Now I took a junk barrel chambered in .223. Cut 1.75" (or about) off the big end to remove the chamber and a bad throat. The muzzle had a pronounced bell mouth, and I cut that off for a 20" barrel. Out of the box, it was a rock solid 5"+ gun! I worked a lot of hand loads thru it and finally got it to shoot 4.25" five shot groups. I loaned the rifle to some bench rest shooters out of Fairland IN (known to be at the top of their game). After a couple weeks they asked how I managed to get it to shoot 4"+ groups? After I put the rifle back together, and still fighting with a really junky trigger; it shot sub half inch groups (same basic loads by the way). The barrel is still junk, and virtually groups are sub half inch, and dipping down to about .38" every once in awhile.

The real difference between the two barrels in my book is purely harmonics (the muzzle is still loose). The chamber of course is better, but I doubt the rifle would have shot two inch groups with that chamber.

A few years back Savage and Remington made a run of 20" barreled .308 bolt guns. Mostly geared towards police, but anybody could buy one. I knew a guy that owned both, plus a short barreled 788 Remington. All three of these rifles out shot nearly every 26" barreled .308 in the area. By the way the 788 out shot the other two!
gary

 

[elkaholic]

It does not surprise me that the 788 outshot the others! That is not all that unusual. I also agree that harmonics is the real issue whether or not the barrel is 20" or 30". Common sense would tell me that shorter (to a degree) might be easier to tune, but I have no proof of that. I think that possibly the sighting radius is part of the equation in accuracy. A 20" barrel may be as capable, or even more capable, of accuracy but any movement is accentuated in the group size. Thats why 2" barreled handguns can be so difficult to hit anything with much past the muzzle.

 

[Mikecr]

If a ~20" barrel was better in a broad sense then by now every new long gun would use ~20" barrels. Truth is there are prices to pay for everything.

Very short barrels are not better for larger capacity cartridges.
For one, there is more to tune than barrel tune. There is also load tune(ie optimum load), and seating tune. Now you could generalize that tune is tune -but that fails tests every time.
When you put an overly short barrel ahead of a large capacity cartridge, you're abandoning any hope of consistent load tune. All that muzzle pressure slapping the back of your Bullets is just not contributing anything good now. And it's varying about, as slow powder burning does when a lot of it isn't burned in the bore, but outside the bore.

You still have barrel tune, and seating, and the gun may shoot well enough with that. For police shooting a 308 out to maybe 80yds(the avg LE sniping dist), it makes sense to prioritize mobility over accuracy. After all, it will shoot plenty good enough there.

What I'm suggesting is that there are reasons larger cartridge guns usually come with longer barrels. It isn't just velocity.

 

[rcoody]

a good comparison is 100yrd bench rest shooting 6mm ppc. They like the short barrels.

then you look at the 600 and 1000 yrd bench rest guns. Won't see any 20" there. I bet the average is 30" and most are straight taper.

 

[elkaholic]

If a ~20" barrel was better in a broad sense then by now every new long gun would use ~20" barrels. Truth is there are prices to pay for everything.

Very short barrels are not better for larger capacity cartridges.
For one, there is more to tune than barrel tune. There is also load tune(ie optimum load), and seating tune. Now you could generalize that tune is tune -but that fails tests every time.
When you put an overly short barrel ahead of a large capacity cartridge, you're abandoning any hope of consistent load tune. All that muzzle pressure slapping the back of your Bullets is just not contributing anything good now. And it's varying about, as slow powder burning does when a lot of it isn't burned in the bore, but outside the bore.

You still have barrel tune, and seating, and the gun may shoot well enough with that. For police shooting a 308 out to maybe 80yds(the avg LE sniping dist), it makes sense to prioritize mobility over accuracy. After all, it will shoot plenty good enough there.

What I'm suggesting is that there are reasons larger cartridge guns usually come with longer barrels. It isn't just velocity.

I would agree with the large capacity for bore with short barrels being a problem. I was making a few generalizations with the rest.......Rich

 

[SidecarFlip]

For me, tube length is predicated on where I shoot the rifle at. Example, I like a shorter barrel here in Michigan in the woods because a long tube is cumbersome to carry around... Gets hung up in the low hanging branches where I hunt up north.

Much easier to deal with a compact rifle.