I don't remember exactly in the 70's when I got my then new Navy Arms M1803 rifle, but it was before Euroarms began selling them. I had already owned and fired my Navy Arms Brown Bess Carbine a lot in Northwest Trade Gun Matches and it proved very reliable. I had also purchased the Navy Arms .69 caliber "Charleville" Pistol that I fired some and was also very reliable as to the ignition. (It also shot surprisingly well at 25 yards considering it had no sights and the grip was HUGE even for my large hands.) My next purchase, though, was the M1803 rifle and that proved an utter disappointment.
I had been firing both my Brown Bess and a hand built flintlock rifle with an original Siler lock a good deal in competition, so it wasn't like I didn't know what I was doing with flinters, but I could NEVER get that M1803 to spark or go off reliably. We had quite a few folks in our club who shot flinters and some flintlock builders, but no one knew how to fix that M1803. Though I was working on WBTS guns back then, I as yet did not know how to work frizzens and change geometry of the cock. The lock on that rifle was just junk and even though I eventually did learn to case harden frizzens, it did not work on that lock. I thought about trying to "percussion" it for use in WBTS reenacting, but just never got around to it.
I thought I might have been the only person to have such problems with the Italian made M1803's, but I later learned lock problems were significant problems many people reported and I never came across a good way to fix them. I eventually sold mine for use as a "decorator rifle" to be hung over a fireplace and I made sure the new owner knew all the problems I had had with the rifle. He did not care, because he had no interest to shoot it. Since I got the rifle for distributor price in the 70's, when I sold it at a much reduced cost over current retail in the late 80's, I did not lose much money I had originally spent. So at least that was something where I got much of my money back, even figuring the loss from the way the dollar had devaluated over at least a decade. I was GLAD to have gotten rid of it and made some of my money back.
Gus