There has been no reference shown that all U.S. guns are proof tested because of insurance regulations.
Here is an excerpt of the Italian manufacturer Pedersoli's proof testing statement where regarding the U.S.A. they state, "Only military contract firearms receive high pressure proof testing under strictly controlled conditions."
I wonder if most U.S. manufacturers are simply test firing or function testing all of their newly produced guns which folks believe to be the same as proof testing when it's not.
Proof testing requires taking precise measurements of critical areas both before and after firing proof loads that exceed established SAAMI pressures by 30%. IMHO that doesn't mean that every manufacturer is proof testing every gun in house that they manufacture.
They may proof test some guns but not necessarily all of them, and not necessarily every manufacturer.
If the critical before and after measurements aren't taken, then how would the manufacturer know that they didn't cause microscopic damage to the gun by proof testing it?
An insurance company wouldn't allow a gun that could have been damaged by proof testing to then be sold on the market.
That's why I believe Pedersoli's statement is generally true that "Only military contract firearms receive high pressure proof testing under strictly controlled conditions."
....Because of the dangers mentioned above, and the fact that no one outside of a testing laboratory or proof house has the proper equipment to measure the pressure and strain produced by any ammunition, the Pedersoli company states that their cartridge rifles are to be fired only with "commercially produced" smokeless powder ammunition or, with black powder ammunition which meets the pressure limits set forth by the European C.I.P or American SAAMI organizations for each caliber or cartridge name.
Pedersoli & Co. like all Italian firearms manufacturers, is required by law, to have every firearm proof tested at the Italian National Proof House in Gardone Italy.
Many other European gun makers also send their complete gun or barreled actions to this same proof house when there is no similar proof house in their home country. Buyers look for proof marks as an assurance of safety and quality so manufacturers pay the extra price to have guns proofed by a recognized govt. controlled proof house.
Below is a copy of the standard letter Pedersoli provides to customers who ask about the proof test pressures for their Black Powder Ctg. Rifles.
It should be noted that in the USA, Federal or State Law does not require the proof testing of civilian firearms and there is no national proof house in the USA for such testing.
Only military contract firearms receive high pressure proof testing under strictly controlled conditions. All other firearms may or may not be proof tested by the manufacturer in some manner and if proof testing is performed, there is no government supervision or control so the customer must rely upon the manufacturers’ reputation in regards to the firearm strength. Fortunately, even though commercial firearms made in the USA do not have proof testing marks they are found to be strong enough for commercial ammunition made according to recognized SAAMI pressure ratings and the customer relies upon the reputation of both the gun and ammo manufacturer.
PEDERSOLI PROOF TESTING STATEMENT
All Pedersoli rifles are proof tested at the (Italian government) National Firing Proof House with smokeless powder cartridges with a pressure exceeding that of the ‘commercial’ factory made ammunition by 30 %.
For the .45-70 caliber we normally recommend the use of commercially made ammunition because of it being easily available on the world market. We show here some warnings about C.I.P. rules:
C.I.P WARNING
Our guns are proof tested according to the rules imposed by C.I.P. (International Proof Commission). Proof test pressure is 30% stronger than the maximum pressure of a commercial cartridge (Pmax.) Pmax pressures are measured in BAR units.....
http://www.bpcr.net/site_docs-resul...li_proof_rules_and_allowable_limits_09-04.htm
I find it highly unlikely that it had been shot before, as the barrel was still intact.