RE: THOMPSON CONTENDER VS. ENCORE
About 45,000 psi. More than that is generally considered a high pressure cartridge.
The contender fires cartridges such as the 30-30, 45-70, and hand gun cartridges. The 30-30 maximum average pressure is 42,000 psi and the 45-70 is a low 28,000 psi.
The encore fires cartridges such as the .270, 30-06, 300 Win mag, 375H&H. Take the .270 Winchester. It's maximum average pressure is 65,000 psi. In fact all of these I listed have maximum average pressures of over 60,000 psi.
Basically the encore is a stronger firearm than the contender and is designed to safely fore these high energy cartridges.