Barrel life..gone in 6 seconds
- Thread starter noneck180
- Start date
Varmint Al figured out that the amount of time a bullet spends in a barrel during firing is under .002 seconds. Al writes: “The approximate time that it takes a 3300 fps muzzle velocity bullet to exit the barrel, assuming a constant acceleration, is 0.0011 seconds. Actual exit times would be longer since the bullet is not under constant acceleration.”
We’ll use the .002 number for our calculations here, knowing that the exact number depends on barrel length and muzzle velocity. But .002 is a good average that errs, if anything, on the side of more barrel operating life rather than less.
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? That’s simple math: 3000 x .002 seconds = 6 seconds.
We’ll use the .002 number for our calculations here, knowing that the exact number depends on barrel length and muzzle velocity. But .002 is a good average that errs, if anything, on the side of more barrel operating life rather than less.
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? That’s simple math: 3000 x .002 seconds = 6 seconds.
At 43,000 cup the peak flame temperature is just reaching the melting point of modern barrel steels. These six seconds might apply to cartridges in the 50,000 cup range "BUT" my 30-30 Winchester has a rated chamber pressure of 38,000 cup well below the melting point of modern steels.
Think about it, the .22 rifles we got as Christmas presents have months of bullet time in the barrel. Have a chrome lined bore, forget the six second rule and don't forget more barrels are damaged by improper cleaning methods than anything else.
The Vickers machine gun barrels were rated for 10,000 rounds or 20 seconds of barrel life. So much for computer software estimates, garbage in, garbage out.
Think about it, the .22 rifles we got as Christmas presents have months of bullet time in the barrel. Have a chrome lined bore, forget the six second rule and don't forget more barrels are damaged by improper cleaning methods than anything else.
The Vickers machine gun barrels were rated for 10,000 rounds or 20 seconds of barrel life. So much for computer software estimates, garbage in, garbage out.
Jordan Smith
CGN Ultra frequent flyer
- Location
- Calgary, AB
A machine gun shoots fast, but it would have to have a bullet entering the throat just as the previous bullet is leaving the muzzle in order to be a direct comparison to the 6-second calculation. This would mean that the gun would have to fire a round a little faster than every 0.002 seconds, which they do not...
Bolivar
CGN Ultra frequent flyer
The original article had nothing to do with cyclic rate. Just adding up the total time a barrel has a bullet actually traveling down the barrel. Really just academically interesting IMO. No practical purpose.
Ladies and Germs
We had a two second rule of thumb until we fired the "water cooled" Vickers machine gun and had 20 seconds of barrel life, the key word is barrel temperature created from the peak flame temperature.
The two second rule doesn't apply to hotter burning cordite powder, this means the two second rule is just an approximation or WAG.
We had a two second rule of thumb until we fired the "water cooled" Vickers machine gun and had 20 seconds of barrel life, the key word is barrel temperature created from the peak flame temperature.
The two second rule doesn't apply to hotter burning cordite powder, this means the two second rule is just an approximation or WAG.
Bolivar
CGN Ultra frequent flyer
I'm actually surprised the life was so short when measured in belts. From my understanding with the way Vickers were sometimes used, you would have to replace the barrels many times (5-10?) per day. That is sort of WOW to me. I'm not calling bull####....I'm just surprised.
