I have the same question but in my case it's about the SKB late model 385 boxlock in 12 Ga and in 28 Ga.

I'm of the opinion that Searcy got started modifying BSS actions before he started making his own.

I'm very concerned about ruining a very rare and expensive shotgun action because I over stressed it.

Very roughly a .470 Nitro at 40,000 PSI will create twice the force against the breach block as a 12 Ga at 11,000 psi

Read Ellis book "making double rifles from shotgun actions and he prefers actions where some type of lock engages the rear of the breach block....I believe he says birds heads