PDA

View Full Version : Barrel Life



Cap1
06-12-2010, 08:31 PM
Would you ever buy a gun if the barrel will only work for less than 10 seconds?

Most guns have barrels that last thousands of rounds without losing accuracy. But how much is a guns barrel life in terms of time actually used? The answer surprised me and it might surprise you too.
According to this calculation the average life (in actual usage) of a barrel is only 5-10 seconds!!

http://bulletin.accurateshooter.com/2010/11/gone-in-six-seconds-barrel-life/
"If a bullet flies at 3000 fps, it will pass through a 24" (two-foot) barrel in 1/1500th of a second. If you have a useful barrel life of 3000 rounds, that would translate to just two seconds of actual bullet-in-barrel operating time.

But itís not that simple. Your bullet starts at zero velocity and then accelerates as it passes through the bore, so the projectileís average velocity is not the same as the 3000 fps muzzle velocity. So how long does a centerfire bullet (with 3000 fps MV) typically stay in the bore? The answer is about .002 seconds.

So, if a bullet spends .002 seconds in the barrel during each shot, and you get 3000 rounds of accurate barrel life, how much actual firing time does the barrel deliver before it loses accuracy? Thatís simple math: 3000 x .002 seconds = 6 seconds."

someone_001
06-12-2010, 08:44 PM
Heard that very low profile or thin barrels are made on order to achieve extreme accuracy and low weight and they would last for couple of shots and multiple shots one after another is not recommended with these type of barrels too.
So its not about MTBF values only but also the purpose.

Vik
06-12-2010, 11:35 PM
Captain saheb, this IS INFORMATION for me.
Thanks

HammadArshad
07-12-2010, 11:46 AM
@Cap1 thanks for the information, so what do you say about less than 6" pistol barrels!

Regards,

ALI GUJJAR
07-12-2010, 03:08 PM
This IS INFORMATION

Denovo87
07-12-2010, 04:48 PM
Never thought of word BARREL LIFE with this perspective, great share Cap1 bro, thanks.

Cap1
07-12-2010, 09:21 PM
Thanks everyone.
@HammadArshad: Good question, I was wondering the same. I would say max 20 seconds by the formula given in the website (not sure its even right, our experts may please vet it).
Assumptions:
A 9mm pistol bullet would travel at say half the muzzle velocity of a rifle bullet, i.e. 3000 fps / 2 = 1500fps. So the time in the barrel would roughly double: 0.002 seconds * 2 = 0.004 seconds in a 24" barrel.
If it spends .004 seconds in a 24" barrel it would spend one-sixth the time in a 4" pistol barrel. So 0.004 / 6 = 0.0006667 seconds per shot.
Say you shoot your pistol for 30,000 rounds before getting rid of it (very few of us would shoot that much with one gun). Your barrel life would be:
30,000 * 0.0006667 = 20 seconds.
Enjoy it while it lasts!
...and think of it... 30,000 9mm rounds @ say Rs.35 each = Rs. 1,050,000. So you get to spend Rs. 52,500 per second just on ammo!! (1,050,000 / 20).

Again, the 'formula' is off some website and is not vetted. But one can guess the actual usage time of a barrel would be a few seconds only any way you calculate it.

Ka_Khan
07-12-2010, 10:13 PM
Interesting calculations.Thanks Cap1 for sharing.We never thought of it before.

bestmagician83
09-12-2010, 12:05 AM
@ CAP1

it is a really mind blowing and shocking information janab.....

Aquarius
09-12-2010, 12:20 AM
Great information indeed Cap1 brother.. thanks for sharing.

HasanJamshad
09-12-2010, 12:12 PM
As brother Denovo said it is a different way of narrating the fact that Accuracy of a certain barrel will last for 3000 rounds. "A Rose is a Rose" there is no need to be alarmed.
Thanks for sharing.

Skeeter60
10-12-2010, 01:30 AM
As brother Denovo said it is a different way of narrating the fact that Accuracy of a certain barrel will last for 3000 rounds. "A Rose is a Rose" there is no need to be alarmed.
Thanks for sharing.
Absolutely. It is the accuracy life of the barrel which is considered. A barrel is considered finished once it loses accuracy, other wise it can continue to shoot indefinitely but in ever enlarging groups.
In high velocity magnum rifles the throat of the barrel(the barrel just ahead of the chamber ) is the first to suffer as it is eroded due to large quantities of propellants forced through it. Once it is elongated the bullet has a relatively longer distance to jump before getting lodged into the rifling and more often than not it yaws and this in bore yaw starts deterioration of accuracy.
Another problem that occurs in all High velocity rifles is the acumilation of a mixture of propellant and lead/copper in the barrel in an area where the Peak Pressure occurs about 10 inches or so ahead of the breach, this swages the bullet as it passes through this constriction in the barrel deteriorating the accuracy. This can be cleaned but with a lot of effort, phosphor bronze brushes and good copper solvents.
A properly cleaned barrel will help increase the life (accurate Life ) of a rifle.

Cap1
11-12-2010, 09:00 PM
@ HasanJamshad, Skeeter60 Sir. Very valuable inputs as always. Yes, absolutely it would be next to impossible to completely end a properly maintained barrel's life just by shooting (especially if one is paying for the ammo himself!). One will have years of good accurate use out of a gun barrel provided one maintains as Sir Skeeter mentioned.
I think the bit of trivia the quoted website was trying to come up with was an estimation of how much time the barrel actually has bullets passing through it. It would definitely be a minute fraction of the time the gun is actually owned.
It would be good and educative for us to know your comments on the assumptions and calculations used as I'm sure they are guesstimates at best and subject to many variable factors.

HUNTER1
14-12-2010, 04:19 PM
Good to hear.

hunter468
24-02-2011, 11:15 AM
@Cap1
nice calculations and astonishing research.