barrel length

[lewellan2]

I have been talking with people about barrel lengths and have read some of the info on 30BR here and am somewhat confused about optimal barrel length.
I recently read the article "Secrets of the Houston Warehouse" by Dave Scott, Precision Shooing-October 1999. and in that article Virgil King and others are quoted as saying that the optimal barrel length was 21-3/4". this being the barrel length that he consistantly shot groups in the .3' and some as small as .25's.
His reasoning was the 21-3/4" barrels had the "Proper" vibration pattern that duplicates well from shot to shot. with most shooters using the 21-3/4" barrel, the most accurate of the large bore group, a .30 cal. shot groups in the .1's.
I see guns here with barrels as long as 30 or more inches. Is the longer barrel for "Vilocity" or is a longer barrel actually better for accuracy.
Dano

 

[12man]

Not to hijack the thread but similar question Is there an optimum barrel length to twist rate? Along this line, how much difference would a 22 inch barrel versus 26 inch barrel both 1-10 twist with bullets in the 70-90 grain range Cartridge is 6mm BR of course.

 

[glo]

Hi lewellen2,
I think you are referring to 30” target length barrels. The length is for velocity and efficiency. The longer the barrel the greater the velocity. The longer the barrel the less the muzzle blast. In practices the longer you sight radius the greater the accuracy. This is because there is less of a numerical error in angle the closer you can get your front sight to the target. Most iron/apertures sights,by memory) are a 28.75 inch radius. So whether you are using a 24” service rifle barrel or a 32” palma barrel the sight radius is still the same. There is no accuracy advantage.

As for the harmonic balance? Well its true. However, it is only true for the same cartridges, shooting the same weight bullet, from the material,chrome-moly vs stainless), at the same target distance. In 1999 I bet this stiff 21 ¾ barrel was chambered for .308 Winchester cartridge; 168gr Sierra Matchking bullet; air-gauged, chrome-molybdenum, Heavy Varmint barrel; with a target distance of 200yards.

In other words there is no one barrel length,harmonically balanced due to that lenght) that shoots better than another.
glo

P.S. The powder used will also change the harmonics of a barrel as well.

 

[glo]

Hi 12man,
When I get home tonight I'll run the numbers but I think you will get about 12fps gain in velocity per inch between 22 and 26 inches for a cartridge of this size,6mm BR). So 4 inches will get you about a 50fps gain in velocity.
glo

Okay, per Load From A Disk the 6mm BR will develop 3280fps with a 70gr berger and 2961 from a 90gr berger using a 24 inch barrel and Varget powder. When corrected by Le Duc's equation the incresses from 22 to 26 inches are 3247 to 3323fps for the 70gr berger and 2930 to 3000fps for the 90gr berger respectivly. That means you are getting a velocity incress of about 73fps over the 4inches or about 18.25fps per inch within the 22 to 26 inches of barrel lenght.

 

[Eddie Harren]

glo, to the best of my recollection, the cartridge used in the "Houston Warehouse" was the 22 PPC. The article was re-published in 1999 but the actual shooting was done much earlier.

 

[glo]

Thanks for the up date and correction DocEd. I was just going by the date. I didn't paying attention to the titled artical. But I hope my point was not lost in the error.
glo