Barrel thickness and pressures

[Drew Hause]

Have been working through the original document and the graphs Pete posted and came up with this.

32 Gr Ballistite (3 Dram Equiv.)
Breech - 2.9 Tons per Square Inch (UK, Long) = 6496 psi (pound force per square inch)
2 1/2" - 2.2 Tons = 4928 psi
6” - 1.2 Tons = 2688 psi
12” - .81 Tons = 1814 psi
18” - .33 Tons = 739 psi
24” - .21 Tons = 470 psi

83 Gr No. 4 Black Powder
Breech - 2.26 Tons = 5062 psi
2 1/2" - 1.96 Tons = 4390 psi
6” - 1.26 Tons = 2822 psi
12” - .9 Tons = 2016 psi
18” - .33 Tons = 739 psi
24” - .21 Tons = 605 psi

SO once again, the pressure is falling rapidly with either Black Powder or Smokeless and is quite low by 18"

[Drew Hause]

Turns out the conversion is alot more complicated

Using the estimate Lead Crusher Pressure (Cp) conversion to PSI (pound force per square inch)
(Cp x 1.5) - .5 = TSI, TSI X 2240 = PSI

32 Gr Ballistite (1 1/8 oz at 1232 fps muzzle velocity = 3 Dram Equiv.)
Breech - 2.9 Tons per Square Inch (UK, Long) = 8624 psi
(2.9 x 1.5 = 4.35, 4.35 - .5 = 3.85 TSI, 3.85 x 2240 = 8624psi)
2 1/2" - 2.2 Tons = 6272 psi
6” - 1.2 Tons = 3718 psi
12” - .81 Tons = 1602 psi
18” - .33 Tons = 1120 psi
24” - .21 Tons = 694 psi

83 Gr No. 4 Black Powder at 1222 fps
Breech - 2.26 Tons = 6474 psi
2 1/2" - 1.96 Tons = 5466 psi
6” - 1.26 Tons = 3114 psi
12” - .9 Tons = 1904 psi
18” - .37 Tons = 1232 psi
24” - .27 Tons = 896 psi

[Eldon Goddard]

Does anyone know how high the thermal stresses are? What kind of temperatures are reached? Or are the thermal stresses small in comparison to the other stresses that they are ignored?