barrel length vs pressure.

[johnmventers398]

i know the longer you go the more speed you get too a point... but will hacking of steel vary the pressure of a given load. so a max pressure load becomes below max pressure? cause pressure and velosity are directly related, does this mean less tube, less velocity = less pressure?

john

 

[dmoran]

Basically there would be no change to "peak pressure". The effecting change will be "exit pressure" and "exit time" only.
Below a pressure trace for example: from a 105gr bullet in a 30" barrel at 3117-Mv

The red + in the trace curve represents "barrel exit", and is where and when the bullet exited the barrel.

Donovan

 

[johnmventers398]

Basically there would be no change to "peak pressure". The effecting change will be "exit pressure" and "exit time" only.
Below a pressure trace for example: from a 105gr bullet in a 30" barrel at 3117-Mv

The red + in the trace curve represents "barrel exit", and is where and when the bullet exited the barrel.

Donovan

thanks.

 

[Webster]

Max pressure must occur about the first 2-3 " of barrel. Look at a light weight rifle barrel, it's large in diameter for the first few inches then tapers very rapidly. Diameter has to be related to the pressure that will be seen.

 

[dmoran]

Webster -

The large portion of the barrel houses the chamber, that is the primary purpose. All the same, peak pressure does typically occur in the first few inches of the chamber's end. That is dependent on powder burn rate as to how far ahead of the chamber that peak pressure will occur. With fast burning powder, like say N-130, peak may occur very close to the chamber. Where as with slow burning powder, like say H-870, peak may not occur for a few inches ahead of the chamber end. Most all internal ballistic programs give predictions to peak pressure points in distance, pressure, and velocity.

My 2-Cents
Donovan

 

[chkunz]

"Hatchers Notebook", page 322 has a graph that shows pressure vs barrel length for a 1903 U. S. Rifle cal 30 with a 150 grain M1906 bullet. The peak pressure is at about 3.5 inches which is near the end of the chamber.