Proof-testing American Rifles

Q: I know that all firearms made in Europe 
and England are proof tested, but also 
that no firearm ever made in the U.S.A 
has ever been subjected to the same 
tests. At least none that I know of. Do 
you know of any American firearms that 
were proofed?Harold JanssenA: Funny you should ask me that. But the 
only U.S firearm that I know of actually 
underwent proof testing was The Gartman 
Custom "Bantamweight" back in the 1950s. 
The adverts stated "each barrel installed 
is proofed at 68,000 to 70,000 psi assuring 
the safety of barrel and action." These 
ultralight sporters weighed about 3kgs 
all-up with scope and mount. The barrels 
were skinny and looked to have an integral
brake on the muzzle. But actually the 
enlarged section of the barrel was a weight 
and not a brake. I believe its purpose was 
to dampen barrel vibrations.