I'm sure the gun is up to the pressures, just that 62,000psi seems a mite high for a double rifle, when folks seem more interested in sub 50,000psi loadings.

As mentioned, the use of appropriate powders will eliminate pressure excursions due to heat.

As Jeff noted, a simple re-chamber (hmmmmmmm - regulation) to the improved variety reduces back thrust to virtually nothing, the chamber walls preventing it's rearward thrust.