Longer barrel need slower powder?

[laylandad]

I just picked up a new Remington 700 Long Range in 30-06. It has a 26" varmint contour barrel. Would the longer barrel benefit more from a slower burning powder or should I stay with the usual suspects?

 

[DrMike]

Stay with the usual powders. Pressure is pressure, unaffected (for all practical purposes) by length of barrel. You will generate somewhat higher velocities as it is.

 

[laylandad]

Thanks, Dr. Mike.....I thought so, but wanted to be sure.

 

[257 Ackley]

Stay with the usual powders. Pressure is pressure, unaffected (for all practical purposes) by length of barrel. You will generate somewhat higher velocities as it is.

Agree...the powder to use is going to be about the cartridge and bullet weight, not barrel length.

 

[laylandad]

Awesome info. Thanks!

 

[desertcj]

I'm not sure this is covering the whole picture. If you are only burning 75% of the powder charge in a 20" barrel but 99% in a 26" than obviously you would be getting more velocity out of the 26" tube. Now switch to a faster powder out of that 20" barrel where you are getting closer to a 100% burn and I bet that your velocity will be much higher than with the slower powder. IMO, barrel length and burn rate do have a correlation.

 

[DrMike]

I'm not sure this is covering the whole picture. If you are only burning 75% of the powder charge in a 20" barrel but 99% in a 26" than obviously you would be getting more velocity out of the 26" tube. Now switch to a faster powder out of that 20" barrel where you are getting closer to a 100% burn and I bet that your velocity will be much higher than with the slower powder. IMO, barrel length and burn rate do have a correlation.

Factor in the expanding volume allowed by the longer barrel, and it compensates for the amount of powder burned. Gas volume is the determinate factor in generating velocity.

 

[Divernhunter]

Tests have shown that the powder that gives the most speed in a longer barrel will also give the most in a shorter barrel. It may go against your reasoning but it is true.

You will also get more muzzle flash in the shorter barrel.

 

[Wis65x55]

It is my understanding that 90plus % of gunpowder is consumed within the first few inches of the rifle chamber. As for the muzzle flash, it is my understanding that what you are observing is what is called "flashover" this occurs once the bullet exits the barrel and the gases behind the bullet reignite.
Keith

 

[Horsethief]

The same cartridge load from a shorter barrel will generally have a lower muzzle velocity than from a longer barrel, but there is no set formula for how much more velocity you'll gain with a longer barrel. Like most cartridges, a 300 Weatherby Magnum will achieve a higher MV from a 26" barrel than a 24" one. I've found the gain or drop is around 30-40 ft/sec per inch of a barrel, depending on the cartridge.
A good load for a 30-06 in one barrel doesn't mean it will be a good load in another barrel, regardless of powder burning speed.

 

[Osprey78]

It is my understanding that 90plus % of gunpowder is consumed within the first few inches of the rifle chamber. As for the muzzle flash, it is my understanding that what you are observing is what is called "flashover" this occurs once the bullet exits the barrel and the gases behind the bullet reignite.
Keith

So it has created it's own backdraft so to speak?...Having starved itself of O2.

 

[laylandad]

Here's a sneak peek. I should have glass and bases / rings mounted by the weeks end.

 

[DrMike]

I trust the rifle will put a permanent grin on your chin each time you drop game with it. They do look attractive.

 

[SJB358]

Looks like a nice rifle. Can't wait to hear about the range results.

 

[Guy Miner]

For several years I had .308's in three different barrel lengths:

20" Browning BLR
24" Remington 700 (Krieger 1:12)
30" Winchester Model 70 (tight bore Krieger 1:13)

Mostly used 168 & 155 grain match ammo in the 24" and 30" barrels, and 165 gr hunting ammo in the BLR. Also, mostly used Varget powder.

Velocities from the 30" Krieger were pretty impressive, easily over 3,000 fps with Varget & 155's.

I got used to seeing 165/168 velocities of about:
20" - 2600-2650 fps
24" - 2750 - 2800 fps
30" - 2900 fps

I didn't do an exhaustive study of different powders, since Varget was producing high scores in matches, with both excellent accuracy and velocity. No sense messing with it...

Wish I could tell you more about the powders, but it was interesting to see 300 hundred fps difference between the 20" BLR and the 30" Winchester with similar loads.

Oh, and Enjoy the new rifle! :grin:

Guy

 

[Divernhunter]

I have a 22", 18" and 15" 308win. I also have a 22" and 15" 257Roberts. I have 24" and 15" 223. I have 15" and 7.5" 454Casull. I have tested many different powders in each. The powders that give the best velocities in the longer barrels also give the best in the short ones.

There was an article years ago in one of the mags where they took a couple of rifles with different cartridges and started a 24-26" as I remember and tested by chopping them 2" at a time and testing. They had the same result except some cartridges will loose more each chop. The powders that worked best in the long barrels also gave the best velocities as the barrels were shortened. Contrary to believe it was the slower powders that were best.