Barrel Lenght Accuracy Question

[Mark M.]

Hello Fellas, looking at purchasing a 17 hmr rifle that's suppressor ready, the rifles I'm considering offer barrel lengths in 16, 18 and 20 inches, from my understanding, anything over 16" does not increase velocity, but, what about accuracy? Is there any advantage in accuracy with a longer barrel for the cartridge?

 

[grauhanen]

anything over 16" does not increase volatility,

What is the "volatility" to which you refer? Do you mean velocity?

Ammo velocity is a thing that seems to concern a lot of shooters, usually unduly.

In any case, with 17hmr and rimfire in general accuracy is dependent more on ammo quality than barrel length. With 17hmr, ammo quality can't be expected to be great. There is no such thing as match quality magnum rimfire ammo currently available.

If you are adding a suppressor perhaps overall length should be among the most important considerations to take into account.

 

[Long_Shot]

I believe that the "16 inches", is possibly in reference to an article that I read years ago. If I remember correctly, the article stated that a .22LR cartridge only needed 16 inches of barrel length to completely burn all of the powder, and would actually start losing velocity, or coasting, until it exits the muzzle. I know, kind of a broad statement today with all of the different .22LR bullet weights and velocity spreads between them.

If I'm wrong, consider it the ramblings of an old shooter.

Also, longer barrels are usually to increase velocity for cartridges that have the powder charges (centerfire), to do so. And, longer barrels on rimfire cartridges to increase sight radius for target (olympic) open sights.
Longer barrels generally have too much "bullet time" in the bore to benefit accuracy. Harmonics and such.

Man, I guess I can ramble on!

 

[snowpro440]

I can't explain it but on .22LR shooting a 16" barrel has not done as well on paper shoots @ 50 and 100 yards, but everyone that has moved to the longer barrels of 20" to 24" has shot much better.

 

[25ring]

Take a look at the barrel lengths of the Remington 37 and Winchester 52 rifles. Both of mine have 28" barrels and although some of that is for sight radius using open sights it sure doesn't hurt the accuracy any.

 

[1Merlin]

More length is more mass. More mass is less or longer sine wave vibration. Less or longer means less violent vibration. Less vibration is better chance of accurate barrel.

If that argument falls flat I will admit to being a member of the herd and follow the old bulls that just about without exception shoot longer barrels. i.e. if it was good enough for Gramps it's good enough for me.

 

[TRSR8]

I believe that the "16 inches", is possibly in reference to an article that I read years ago. If I remember correctly, the article stated that a .22LR cartridge only needed 16 inches of barrel length to completely burn all of the powder, and would actually start losing velocity, or coasting, until it exits the muzzle. I know, kind of a broad statement today with all of the different .22LR bullet weights and velocity spreads between them.

If I'm wrong, consider it the ramblings of an old shooter.

Also, longer barrels are usually to increase velocity for cartridges that have the powder charges (centerfire), to do so. And, longer barrels on rimfire cartridges to increase sight radius for target (olympic) open sights.
Longer barrels generally have too much "bullet time" in the bore to benefit accuracy. Harmonics and such.

Man, I guess I can ramble on!

Really? Wonder why all those custom RFBR guns sport barrels 24”-26”?

 

[Long_Shot]

Like I said, this article was in reference to the powder burn time, nothing to do with accuracy.

 

[25ring]

Really? Wonder why all those custom RFBR guns sport barrels 24”-26”?

Possibly it's the optimum length for running a tuner.

 

[Mark M.]

I believe that the "16 inches", is possibly in reference to an article that I read years ago. If I remember correctly, the article stated that a .22LR cartridge only needed 16 inches of barrel length to completely burn all of the powder, and would actually start losing velocity, or coasting, until it exits the muzzle. I know, kind of a broad statement today with all of the different .22LR bullet weights and velocity spreads between them.

If I'm wrong, consider it the ramblings of an old shooter.

Also, longer barrels are usually to increase velocity for cartridges that have the powder charges (centerfire), to do so. And, longer barrels on rimfire cartridges to increase sight radius for target (olympic) open sights.
Longer barrels generally have too much "bullet time" in the bore to benefit accuracy. Harmonics and such.

Man, I guess I can ramble on!

The 16" velocity info came from Bullberry, and it was for the 17 HMR

 

[swd]

Really? Wonder why all those custom RFBR guns sport barrels 24”-26”?

Barrels need to be flexible enough for the tuners to be effective. Short barrels are too stiff.

 

[ronsatspokane]

Hello Fellas, looking at purchasing a 17 hmr rifle that's suppressor ready, the rifles I'm considering offer barrel lengths in 16, 18 and 20 inches, from my understanding, anything over 16" does not increase velocity, but, what about accuracy? Is there any advantage in accuracy with a longer barrel for the cartridge?

The 16 inch barrel thing is a fallacy.

For one) it depends on the powder. If it is a pistol round the powder should be hotter so that it burns faster and works in even a shorter barrel. If it is not then you are wasting over half the powder when the round is fired in a pistol with a barrel at 4, 6 or 8 inches versus the mythical 16 inches. If it is a long range round then "in theory" it would be a slower burning powder that may still be cooking well past 16 inches.

For two) Let's say that the average standard velocity 22 with a 40 grain does finish burning in 16 inches. That would be the peak of the pressure. As the bullet continues to move down the barrel the pressure decreases but is still more than sufficient to drive the bullet out of the barrel and overcome the resistance even in a 29 inch barrel like a CZ 452 ultra lux. If there was not sufficient pressure, then the bullet would either stop in the barrel or when the bullet exited the barrel it would sound anywhere from as loud as opening a pop can to sneaking a fart in the church pew. You would not need hearing protection. That said, I don't use hearing protection with most rimfire rifles regardless of barrel length. Pistols are another story. To deny that the bullet is not being driven forward past peak pressure you would have to also argue that the bullet does not start moving until maximum pressure is reached. If you look at the pressure curve associated with any cartridge you will note that the projectile accelerates from the moment the powder lights and continues to build speed through peak pressure and beyond. In F Class we run 30 to 32 inch barrels. It is generally assumed that each inch in length as 25-50 fps. They only go to 18 inches with this chart with 22's. Do you think velocity drops after 18 inches? I don't.

BBTI - Ballistics by the Inch :: .22 Results

(statement of intent)

www.ballisticsbytheinch.com

For three) I wonder how many of those who tested the 16 inch velocity limit were testing with semi-auto rifles. At some point as the barrel length increases, the spent round would be extracted and the pressure would pour out the breech. In that sense one can see how a longer barrel length could be detrimental.

So, I recommend a competition Anschuz, Feinwerkbau or Walther. Most of them have 25 inch barrels.

 

[sacre]

That 16" BS has been repeated so many times people belive it.

 

[TRSR8]

Like I said, this article was in reference to the powder burn time, nothing to do with accuracy.

Perhaps you want to re read your last sentence. And it does seem to have far more to do than tuners.
The better barrels are very close in performance even before tuner is installed

 

[Boltpistol]

That 16" length for a 22lr's highest velocity is questionable. A test in 2015 with a CZ 452 was posted on Shooters Forum. It started with the factory 24 1/4" barrel, cut off one inch at a time and checked velocity for 10 shots, then repeated down to 17 1/4" length long. The results here condensed for 10 different types of 22 ammo. The highest velocity was at this length--- Eley Tenex - 20 1/4" at 1095 FPS
Lapua Midas Plus --- 20 1/4" at 1111 FPS
Eley Force ----------- 22 1/4" at 1198 FPS
CCI Mini Mag -------- 21 1/4" at 1228 FPS
SK Standard ---------- 21 1/4" at 1059 FPS
Eley Contact ---------- 20 1/4" at 1976 FPS
Fiocchi Subsonic ----- 21 1/4" at 1061 FPS
Eley Sport ------------ 20 1/4" at 1099 FPS
CCI Stinger ----------- 22 1/4" at 1558 FPS
Fiocchi Ultrasonic ---- 21 1/4" at 1294 FPS
So you see that * none * of these were fastest at 17 1/4 " of barrel length. This test was posted on Feb. 25, 2015 by Butch Lambert. It looks like the 20 to 22 inch barrel gives the highest velocity in 22 Long Rifle. So happy shooting and may old wife's tales die.