Larry, Miller,
I agree with your suppositions. However, the important factor is not pressure, when using a diameter reducing sleeve to facilitate shooting a smaller shell, it's the stress on the original gun barrel that we're really concerned about. Given the variables in the materials used for that sleeve, only straingage testing would be reliable in determining what the reduction (and there will be a significant reduction) in stress is due to a smaller diameter shell fired in a reducing sleeve.
For example, a 10,000 psi 410 shell fired in a 12g reducing sleeve that did not provide any additional pressure containment itself (theoretically), would exert less stress on the gun barrel than a 10,000 psi 12g shell fired in that barrel.
A 10,000 psi 20g shell fired in 12g reducing sleeve that didn't provide any support will exert more stress on the gun barrel than the 410 example above, but less than a 10,000 psi 12 shell fired in that gun.
Last edited by Chuck H; 02/25/10 10:19 AM.
