How Does Barrel Length Affect Overall Power?

cirelaw · 08-14-2017, 05:03 PM

Was the same round used in all models? Does the rifling tend to slow the bullet down because of friction or does it mearly increase the speed and trajectory! I watched my videos and still can't find an answer?

Chickenthief · 08-14-2017, 06:06 PM

Yes and no.

Thats a good answer right ;-)
It depends, is a more appropriate answer.
If the powder used is fast enough and the barrel long enough it ends up slowing the bullet down.

Take a look here:
http://www.ballisticsbytheinch.com/9luger.html

See at 18" the speed has dropped.

mrerick · 08-14-2017, 06:11 PM

There are a number of dynamic forces involved in firearms ballistics from ignition through terminal energy transfer.

The gliding surface of a bullet against the rifling and side of the barrel certainly encounters friction all the time it's traveling down a barrel. As long powder continues burning and creating gas while the bullet still plugs the end of things, the bullet will accelerate. For most loads, the longer the barrel, the faster the projectile exits the muzzle of the barrel. This also increases the amount of terminal energy transferred by the bullet.

The size of the powder load and the burning speed of the powder determines whether it continues to burn while the bullet travels down the barrel. If it's not complete by the time the bullet exits the barrel, you get muzzle flash in clear air behind the bullet.

There are, of course, other forces at work. There is some resistance involved in the bullet exiting the cartridge case, and more involved when the bullet has jumped the air gap and starts engaging the rifling, biting into the lands. From that moment, considerable friction expends heat as the bullet bearing surface glides down the barrel. Pistol ammunition for 9mm Luger generates just under 35,000. More for NATO and +P.

Marc

cirelaw · 08-14-2017, 06:30 PM

Awesome!! TKS Which of the five fires the longest would you think!!

mrerick · 08-14-2017, 07:16 PM

Well, that's another question completely.

The one that fires the longest is the one with more cartridges.

The one that fires the farthest relates to the ballistics...

It would be the one with the highest muzzle velocity and the best ballistic coefficient in flight.

A 9mm Luger cartridge can be designed to fire a subsonic or super sonic load. The speed affects the air resistance it encounters on it's journey.

The bullet weight determines how fast it drops toward earth.

Speed of sound is 1,125 feet per second in dry air.

This chart lists a number of commercial 9mm loads:

http://www.ballistics101.com/9mm.php

cirelaw · 08-14-2017, 08:07 PM

Does the barrel length have anything to do with any of the factors you discuss? ie snub nose VRS carbine barrel or Kentucky Rifle~

mrerick · 08-14-2017, 09:30 PM

Yes - given everything else unchanged, the longer the barrel, the higher the muzzle velocity as long as powder continues burning while the bullet is in the barrel. Once it leaves the barrel, the interaction between bullet weight, bullet shape, speed (above or below the speed of sound), air, humidity, heat and barometric pressure all affects the flight of the bullet.

It's quite a science, and is science on steroids when you start to talk about large projectiles like the shells fired from naval guns and rockets.

cirelaw · 08-14-2017, 10:53 PM

Thank You, you explained it well! That is why adjustable sight do come in handy!

Chickenthief · 08-15-2017, 08:25 AM

Please look at the link: http://www.ballisticsbytheinch.com/9luger.html

It clearly shows that speed increases up til 17" barrel length but at 18" speed starts to drop again.
That's when powder has stopped working on the bullet and friction has gained the upper hand.

Eugen · 08-15-2017, 08:39 AM

Quote:

Originally Posted by Chickenthief

Please look at the link: http://www.ballisticsbytheinch.com/9luger.html

It clearly shows that speed increases up til 17" barrel length but at 18" speed starts to drop again.

...and there goes my dream for a Luger with an 18" barrel.

Eric, you've got a great collection/display of varying barrel length Lugers. Thanks for posting the question. I always wondered about that question as well. Lastly, thanks for all the informative responses. Such wonderful contributors on this fourm.

cirelaw · 08-15-2017, 10:32 AM

Awesome! Your dreams have been realized!

cirelaw · 08-15-2017, 10:42 AM

1920 was a very busy long year!

Rick W. · 08-15-2017, 10:46 AM

I always heard that with a 22 rimfire, that about 14 inches was about it for speed, guess that is why bloop tubes were added to some fancy rifles.

Folks are right about complexity on this query. Seems to never end variables in the equation of result.

Longer barrels can be milder to the user to use, all things the same; shorter barrels are easy to carry, but can suffer noise, blast etc.

one thing to remember about barrel length, is that your range to the target is usually shorter.

Rick W.

mrerick · 08-15-2017, 11:55 AM

You've also discovered one reason that a special DWM load was designed for the Luger Carbine...

It would be possible to adapt loads to the longer barrels. Slower burning powder would do the trick.

In order to proceed, you'd need an instrumented barrel to ensure that what you load is safe. Both too little and too much powder can cause overpressure.

cirelaw · 08-15-2017, 12:17 PM

I believe they were 7.65 that were designed for carbines. In America they used USA born ammo, I believe!!

Eugen · 08-15-2017, 01:48 PM

Regarding length, remember it not how long your barrel is, but how you use it.

mrerick · 08-15-2017, 02:21 PM

Yes - DWM Luger Carbines were in the .30 Luger / 7.65mm cartridge - but they used a specially loaded version of the cartridge.

cirelaw · 08-15-2017, 06:57 PM

I've read a few 1920s were in 9mm. I would love to shoot mine 7.65 but I would probobly blow it up!! There are beautuful and yes has 3 holes drilled in the stock. At first I thought it was for hiding your stash!! PS Jerrys work!

DonVoigt · 08-15-2017, 07:03 PM

Quote:

Originally Posted by cirelaw

I've read a few 1920s were in 9mm. I would love to shoot mine 7.65 but I would probobly blow it up!! There are beautuful and yes has 3 holes drilled in the stock. At first I thought it was for hiding your stash!!

Eric,
It is NOT likely to "blow up"!

I see no reason not to fire it if you really want to; chances are very slim for breaking a numbered part.
Anyway it is only money.

cirelaw · 08-15-2017, 07:15 PM

I hesitant because first its Debbys and a few years back I was removing the foward grip and it broke in 3 sharp pieces. GT saved my life! I did fire my 1914 DWM artillery and was amazed the kick from a little 9mm. Since then Uncle George got me a rebuilt perfect reblued shooter with a swiss barrel. WOW!!! Is the kick the same on all models.

08-14-2017, 05:03 PM	#1
cirelaw Lifer Lifetime Forum Patron Join Date: Dec 2003 Location: PORT ST LUCIE, FLORIDA Posts: 12,216 Thanks: 6,209 Thanked 4,133 Times in 2,173 Posts	How Does Barrel Length Affect Overall Power? Was the same round used in all models? Does the rifling tend to slow the bullet down because of friction or does it mearly increase the speed and trajectory! I watched my videos and still can't find an answer? Attached Thumbnails

08-14-2017, 06:11 PM	#3
mrerick Super Moderator - Patron LugerForum Life Patron Join Date: Dec 2009 Location: Eastern North Carolina, USA Posts: 3,900 Thanks: 1,372 Thanked 3,094 Times in 1,503 Posts	There are a number of dynamic forces involved in firearms ballistics from ignition through terminal energy transfer. The gliding surface of a bullet against the rifling and side of the barrel certainly encounters friction all the time it's traveling down a barrel. As long powder continues burning and creating gas while the bullet still plugs the end of things, the bullet will accelerate. For most loads, the longer the barrel, the faster the projectile exits the muzzle of the barrel. This also increases the amount of terminal energy transferred by the bullet. The size of the powder load and the burning speed of the powder determines whether it continues to burn while the bullet travels down the barrel. If it's not complete by the time the bullet exits the barrel, you get muzzle flash in clear air behind the bullet. There are, of course, other forces at work. There is some resistance involved in the bullet exiting the cartridge case, and more involved when the bullet has jumped the air gap and starts engaging the rifling, biting into the lands. From that moment, considerable friction expends heat as the bullet bearing surface glides down the barrel. Pistol ammunition for 9mm Luger generates just under 35,000. More for NATO and +P. Marc __________________ Igitur si vis pacem, para bellum - - Therefore if you want peace, prepare for war.

08-14-2017, 07:16 PM	#5
mrerick Super Moderator - Patron LugerForum Life Patron Join Date: Dec 2009 Location: Eastern North Carolina, USA Posts: 3,900 Thanks: 1,372 Thanked 3,094 Times in 1,503 Posts	Well, that's another question completely. The one that fires the longest is the one with more cartridges. The one that fires the farthest relates to the ballistics... It would be the one with the highest muzzle velocity and the best ballistic coefficient in flight. A 9mm Luger cartridge can be designed to fire a subsonic or super sonic load. The speed affects the air resistance it encounters on it's journey. The bullet weight determines how fast it drops toward earth. Speed of sound is 1,125 feet per second in dry air. This chart lists a number of commercial 9mm loads: http://www.ballistics101.com/9mm.php __________________ Igitur si vis pacem, para bellum - - Therefore if you want peace, prepare for war.

08-14-2017, 09:30 PM	#7
mrerick Super Moderator - Patron LugerForum Life Patron Join Date: Dec 2009 Location: Eastern North Carolina, USA Posts: 3,900 Thanks: 1,372 Thanked 3,094 Times in 1,503 Posts	Yes - given everything else unchanged, the longer the barrel, the higher the muzzle velocity as long as powder continues burning while the bullet is in the barrel. Once it leaves the barrel, the interaction between bullet weight, bullet shape, speed (above or below the speed of sound), air, humidity, heat and barometric pressure all affects the flight of the bullet. It's quite a science, and is science on steroids when you start to talk about large projectiles like the shells fired from naval guns and rockets. __________________ Igitur si vis pacem, para bellum - - Therefore if you want peace, prepare for war.

08-15-2017, 10:32 AM	#11
cirelaw Lifer Lifetime Forum Patron Join Date: Dec 2003 Location: PORT ST LUCIE, FLORIDA Posts: 12,216 Thanks: 6,209 Thanked 4,133 Times in 2,173 Posts	The Ultimate~ Awesome! Your dreams have been realized! Attached Thumbnails

08-14-2017, 06:06 PM	#2
Chickenthief User Join Date: Dec 2016 Location: Denmark Posts: 135 Thanks: 0 Thanked 131 Times in 48 Posts	Yes and no. Thats a good answer right ;-) It depends, is a more appropriate answer. If the powder used is fast enough and the barrel long enough it ends up slowing the bullet down. Take a look here: http://www.ballisticsbytheinch.com/9luger.html See at 18" the speed has dropped.

08-14-2017, 06:30 PM	#4
cirelaw Lifer Lifetime Forum Patron Join Date: Dec 2003 Location: PORT ST LUCIE, FLORIDA Posts: 12,216 Thanks: 6,209 Thanked 4,133 Times in 2,173 Posts	Awesome!! TKS Which of the five fires the longest would you think!!

08-14-2017, 08:07 PM	#6
cirelaw Lifer Lifetime Forum Patron Join Date: Dec 2003 Location: PORT ST LUCIE, FLORIDA Posts: 12,216 Thanks: 6,209 Thanked 4,133 Times in 2,173 Posts	Does the barrel length have anything to do with any of the factors you discuss? ie snub nose VRS carbine barrel or Kentucky Rifle~

08-14-2017, 10:53 PM	#8
cirelaw Lifer Lifetime Forum Patron Join Date: Dec 2003 Location: PORT ST LUCIE, FLORIDA Posts: 12,216 Thanks: 6,209 Thanked 4,133 Times in 2,173 Posts	Thank You, you explained it well! That is why adjustable sight do come in handy!

08-15-2017, 08:25 AM	#9
Chickenthief User Join Date: Dec 2016 Location: Denmark Posts: 135 Thanks: 0 Thanked 131 Times in 48 Posts	Please look at the link: http://www.ballisticsbytheinch.com/9luger.html It clearly shows that speed increases up til 17" barrel length but at 18" speed starts to drop again. That's when powder has stopped working on the bullet and friction has gained the upper hand.

08-15-2017, 10:42 AM	#12
cirelaw Lifer Lifetime Forum Patron Join Date: Dec 2003 Location: PORT ST LUCIE, FLORIDA Posts: 12,216 Thanks: 6,209 Thanked 4,133 Times in 2,173 Posts	1920 was a very busy long year! Attached Thumbnails

08-15-2017, 10:46 AM	#13
Rick W. User Join Date: Jun 2002 Posts: 339 Thanks: 81 Thanked 359 Times in 198 Posts	I always heard that with a 22 rimfire, that about 14 inches was about it for speed, guess that is why bloop tubes were added to some fancy rifles. Folks are right about complexity on this query. Seems to never end variables in the equation of result. Longer barrels can be milder to the user to use, all things the same; shorter barrels are easy to carry, but can suffer noise, blast etc. one thing to remember about barrel length, is that your range to the target is usually shorter. Rick W.

08-15-2017, 11:55 AM	#14
mrerick Super Moderator - Patron LugerForum Life Patron Join Date: Dec 2009 Location: Eastern North Carolina, USA Posts: 3,900 Thanks: 1,372 Thanked 3,094 Times in 1,503 Posts	You've also discovered one reason that a special DWM load was designed for the Luger Carbine... It would be possible to adapt loads to the longer barrels. Slower burning powder would do the trick. In order to proceed, you'd need an instrumented barrel to ensure that what you load is safe. Both too little and too much powder can cause overpressure. __________________ Igitur si vis pacem, para bellum - - Therefore if you want peace, prepare for war.

08-15-2017, 12:17 PM	#15
cirelaw Lifer Lifetime Forum Patron Join Date: Dec 2003 Location: PORT ST LUCIE, FLORIDA Posts: 12,216 Thanks: 6,209 Thanked 4,133 Times in 2,173 Posts	I believe they were 7.65 that were designed for carbines. In America they used USA born ammo, I believe!!

08-15-2017, 01:48 PM	#16
Eugen User Join Date: Apr 2016 Location: Newburgh,IN Posts: 768 Thanks: 372 Thanked 603 Times in 320 Posts	Regarding length, remember it not how long your barrel is, but how you use it. __________________ “God created war so that Americans would learn geography.” ― Mark Twain

08-15-2017, 02:21 PM	#17
mrerick Super Moderator - Patron LugerForum Life Patron Join Date: Dec 2009 Location: Eastern North Carolina, USA Posts: 3,900 Thanks: 1,372 Thanked 3,094 Times in 1,503 Posts	Yes - DWM Luger Carbines were in the .30 Luger / 7.65mm cartridge - but they used a specially loaded version of the cartridge. __________________ Igitur si vis pacem, para bellum - - Therefore if you want peace, prepare for war.

08-15-2017, 06:57 PM	#18
cirelaw Lifer Lifetime Forum Patron Join Date: Dec 2003 Location: PORT ST LUCIE, FLORIDA Posts: 12,216 Thanks: 6,209 Thanked 4,133 Times in 2,173 Posts	I've read a few 1920s were in 9mm. I would love to shoot mine 7.65 but I would probobly blow it up!! There are beautuful and yes has 3 holes drilled in the stock. At first I thought it was for hiding your stash!! PS Jerrys work! Attached Thumbnails

08-15-2017, 07:15 PM	#20
cirelaw Lifer Lifetime Forum Patron Join Date: Dec 2003 Location: PORT ST LUCIE, FLORIDA Posts: 12,216 Thanks: 6,209 Thanked 4,133 Times in 2,173 Posts	I hesitant because first its Debbys and a few years back I was removing the foward grip and it broke in 3 sharp pieces. GT saved my life! I did fire my 1914 DWM artillery and was amazed the kick from a little 9mm. Since then Uncle George got me a rebuilt perfect reblued shooter with a swiss barrel. WOW!!! Is the kick the same on all models.