A proof pressure of 1100 kg/cm2 = 15,646 psi, for a service load pressure of about 10,000 psi
The pressure numbers were however obtained using lead crushers, and pressure derived by modern piezo transducers would be 10-14% higher.
I would be very cautious about lengthening the chambers of a light weight continental 20g, and then only by an expert like Dean Harris at Skeets Gun Shop
Tahlequah, OK
918-456-4749
The OPs gun is a 16 Drew, not a 20.
The further I get down the road of life, the more French guns I see. What I haven’t seen on that road is a FRENCH gun, with FRENCH proof that suffers from thin walls. Quite the opposite, typically.
They might be out there. But, they ain’t running around in bunches.
The rest of the stuff, off the continent, I have no clue.
Best,
Ted
