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Bart B. · April 6, 2012, 02:31 PM

Had to get back to this thread.

Here's two barrels fit to receivers bolted in a stock; both 30 caliber. The groove diameter of .306 inch was used to equal what a typical 4-groove rifled hole area of .308" groove diameter would be (.0736 square inch). My software only uses one diameter for the hole in the barrel.

Use the profile below for dimensions listed:

First barrel, typical 24" sporter rifle:

groove diameter = 0.306 inch
breech diameter A= 1.25 inch
reinforce large diameter B= 1.25 inch
reinforce small diameter C= 0.8 inch
muzzle diameter D= 0.6 inch

reinforce length AB= 2.75 inch
reinforce taper length BC= 3.25 inch
main taper length CD= 18 inch

total_length= 24 inch
total_weight= 3.191 lb

Second barrel, typical 30" Palma rifle:

groove diameter = 0.306 inch
breech diameter A= 1.25 inch
reinforce large diameter B= 1.25 inch
reinforce small diameter C= 0.92 inch
muzzle diameter D= 0.82 inch

reinforce length AB= 2.5 inch
reinforce taper length BC= 2.5 inch
main taper length CD= 25 inch

total_length= 30 inch
total_weight= 5.095 lb

Which one's stiffer and by how much?

One of them vibrates at about 71.5 cycles per second and that's the frequency where the greatest amount of bore axis angular spread happens at the muzzle as it whips in the vertical axis for that barrel's contour. It goes through one cycle in about 14 milliseconds. Bullets take a little over 1 millisecond to go from case mouth to the muzzle.

PS: I might be persuaded to calculate then compare two other barrels, but only for nice guys.

April 6, 2012, 02:31 PM	#16
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	Had to get back to this thread. Here's two barrels fit to receivers bolted in a stock; both 30 caliber. The groove diameter of .306 inch was used to equal what a typical 4-groove rifled hole area of .308" groove diameter would be (.0736 square inch). My software only uses one diameter for the hole in the barrel. Use the profile below for dimensions listed: First barrel, typical 24" sporter rifle: groove diameter = 0.306 inch breech diameter A= 1.25 inch reinforce large diameter B= 1.25 inch reinforce small diameter C= 0.8 inch muzzle diameter D= 0.6 inch reinforce length AB= 2.75 inch reinforce taper length BC= 3.25 inch main taper length CD= 18 inch total_length= 24 inch total_weight= 3.191 lb Second barrel, typical 30" Palma rifle: groove diameter = 0.306 inch breech diameter A= 1.25 inch reinforce large diameter B= 1.25 inch reinforce small diameter C= 0.92 inch muzzle diameter D= 0.82 inch reinforce length AB= 2.5 inch reinforce taper length BC= 2.5 inch main taper length CD= 25 inch total_length= 30 inch total_weight= 5.095 lb Which one's stiffer and by how much? One of them vibrates at about 71.5 cycles per second and that's the frequency where the greatest amount of bore axis angular spread happens at the muzzle as it whips in the vertical axis for that barrel's contour. It goes through one cycle in about 14 milliseconds. Bullets take a little over 1 millisecond to go from case mouth to the muzzle. PS: I might be persuaded to calculate then compare two other barrels, but only for nice guys. Last edited by Bart B.; April 6, 2012 at 04:40 PM.