Barrel Length and Muzzle Velocity
Question:
How much does the barrel length effect the muzzle velocity? Take the 30-30 caliber for example. With a 24 inch barrel. The muzzle velocity in 2480fps. What would the velocity be if the barrel were 20 inches long? Would there be a large drop? * Sent from RemarQ http://www.remarq.com The Internet’s Discussion Network * The fastest and easiest way to search and participate in Usenet – Free! Visit the rec.hunting and rec.hunting.dogs FAQ Home Page at: http://sportsmansweb.com/hunting/
Response:
you will gain about 100 fps for every inch of barrel. So, you would loose around 400 fps
> How much does the barrel length effect the muzzle velocity? Take the > 30-30 caliber for example. With a 24 inch barrel. The muzzle velocity > in 2480fps. What would the velocity be if the barrel were 20 inches > long? Would there be a large drop? > * Sent from RemarQ http://www.remarq.com The Internet’s Discussion Network * > The fastest and easiest way to search and participate in Usenet – Free! > Visit the rec.hunting and rec.hunting.dogs FAQ Home Page at: > http://sportsmansweb.com/hunting/
Visit the rec.hunting and rec.hunting.dogs FAQ Home Page at: http://sportsmansweb.com/hunting/
Response:
on a 30-30, about 30fps per inch – Hide quoted text — Show quoted text —— Original Message —– Sent: Monday, December 20, 1999 8:45 AM > How much does the barrel length effect the muzzle velocity? Take the > 30-30 caliber for example. With a 24 inch barrel. The muzzle velocity > in 2480fps. What would the velocity be if the barrel were 20 inches > long? Would there be a large drop? > * Sent from RemarQ http://www.remarq.com The Internet’s Discussion Network * > The fastest and easiest way to search and participate in Usenet – Free! > Visit the rec.hunting and rec.hunting.dogs FAQ Home Page at: > http://sportsmansweb.com/hunting/
Visit the rec.hunting and rec.hunting.dogs FAQ Home Page at: http://sportsmansweb.com/hunting/
Response:
> > How much does the barrel length effect the muzzle velocity? Take the > 30-30 caliber for example. With a 24 inch barrel. The muzzle velocity > in 2480fps. What would the velocity be if the barrel were 20 inches > long? Would there be a large drop?
> you will gain about 100 fps for every inch of barrel. So, you would loose > around 400 fps
Tony and anyone else who may know, I have heard that you lose the 100fps per inch also but I am wondering if that is a generalization that is an estimate and not always true. With that number one could guess that a 24 inch barrel is only capable of 2400 fps which is not true. So much depends on the weight of the bullet and the type of powder and primer. I have also heard that for example a shotgun slug shell burns most all its powder in the first 16 inches. This is specifically because there are 18 to 24 inch slug barrels readily available. Once the powder has completed its burn, would not any excess barrel actually slow the bullet down do to friction? Though the 20 inch barrel on the 30-30 for example may not be capable of the same top velocity as the 24, with the proper loads for that length, couldn’t you under normal circumstances expect to be able to find the performance that is needed? I am not a expert by any means and just wondered what the true case may be. Ed Visit the rec.hunting and rec.hunting.dogs FAQ Home Page at: http://sportsmansweb.com/hunting/
Response:
- Hide quoted text — Show quoted text -> Tony and anyone else who may know, > I have heard that you lose the 100fps per inch also but I am wondering if > that is a generalization that is an estimate and not always true. With that > number one could guess that a 24 inch barrel is only capable of 2400 fps > which is not true. So much depends on the weight of the bullet and the type > of powder and primer. I have also heard that for example a shotgun slug > shell burns most all its powder in the first 16 inches. This is > specifically because there are 18 to 24 inch slug barrels readily available. > Once the powder has completed its burn, would not any excess barrel actually > slow the bullet down do to friction? Though the 20 inch barrel on the 30-30 > for example may not be capable of the same top velocity as the 24, with the > proper loads for that length, couldn’t you under normal circumstances expect > to be able to find the performance that is needed? I am not a expert by any > means and just wondered what the true case may be. > Ed
Ed, you are right, there are no hard rules in this (or most other things). In fact, the powder is burnt during the first few inches of bullet travel even with the biggest magnums and slowest powders. But even after that, the pressure continues to accelerate the bullet. In some point the friction overcomes the pressure and the bullet starts to slow down. This does not often happen in rifles (so much powder), shotguns (so little friction) or handguns (so short barrels), but it does happen in 22LR rifles, where maximum velocity with standard ammo comes from about 16" barrel, and in pistol-caliber carbines with fast-burning pistol powdered ammo. 30-30, with its modest pressure and small charges, is ok in a 20" barrel, but a 300 Mag, for example, would gain velocity with every extra inch up to somewhere not very practical…30"? Again, this depends very much on the powder used. For example Speer and Sierra manuals have same calibers in both rifle and pistol, and the best loads are often with different powders. Speer also lists tried velocity variations with different barrel lenghts for some calibers. That is the way to do it! Heikki — Er
