Proof testing would be the least of my concerns.
Did you see the page showing their production facility and machining equipment?--->>>
https://americanguncraft.com/equipment/
I'll admit that there's fine details lacking about some aspects of the product [such as the quality of the locks, overall construction, composition & finish], and that the phillips screws look cheap
and out of place.
And they posted a video review of the Pedersoli Howdah by Hickock45 instead of their own gun on their own website.
But it is made in the USA and not China, Mexico, India, Brazil or in the former Eastern Bloc countries, all places where muzzle loaders have been produced and imported from.
I would think that they've done their own proof testing to protect their company and jobs, and from being sued under US product liability laws.
Why would they risk bringing a gun to market if it weren't able to pass minimal proof testing?
There's something to be said about American pride and ingenuity.
I think that they're trying to save Americans some money from needing a pay a king's ransom for Pedersoli imports, some of which are very high priced due their extra fancy wood & finish.
As long as the gun is safe, durable and functional, most people would appreciate saving some money and buying an American made gun.
But IMO they should at least be able to produce a video of their own gun being fired.
AFAIK this is the only video on their youtube channel: