It’s not so much relying on ignorance, as much as relying on a lack of time/resources.
The ignorance part you are underestimating, mainly because it’s Massachusetts. I’m willing to bet that at least 80% of prosecutors in the district courts have never held a firearm let alone fired one. The gun laws here have been outrageous for decades and most people who grew up here think if you hold a gun, your house is going to explode (hyperbole but you get the point). The laws here are written by people that have no experience with firearms and enforced by prosecutors that also have no experience with firearms.
You can be in a certain mall in Nashua NH lawfully carrying a glock (aren’t allowed to buy those in MA) with a 17 round magazine. Entirely lawful. However if you walk to the other side of the mall that is over the MA state line, you are now committing a felony that requires a mandatory 18 months in jail for the gun and/or 2.5 years mandatory in state prison for possessing the magazine. If you don’t even have the gun, but have the magazine and no ammo - 2.5 years mandatory state prison. If you have the gun but it’s missing pieces and will never be able to fire again because it’s been run over by a train - mandatory 18 months in jail.
So that’s a long way of saying, the laws don’t make sense and most people here think guns are bad and stay away from them. So there is very much a possibility that a prosecutor will take this case, not have enough trial experience to recognize the flaws in this case, and think a gun is a gun I can prove it’s a gun, and then lose. (Most prosecutors in the district courts, where this case is, are new lawyers with little experience and big chips on their shoulders because they’re new lawyers.)
However the more likely scenario in this case is they hand the firearm back to their expert and then tell them what I’m trying to do. Their ballistics expert will recognize all of the things you have all pointed out, and the prosecutor will either not know how to get any of the information into evidence (inexperience, and it’s harder than it looks on tv) or they will know exactly how to get it into evidence but will not be willing or able to spend the time and resources to do what they need to do go forward with the case. And then the case is dropped.
The last scenario is what I’m banking on.
Thankfully they didn’t close down all the law schools, so I’m familiar with the rules of evidence. All the points that are blatantly obvious to the people on this forum, can’t just be introduced into evidence by some random person. It would take a considerable amount of time to find the right witness, and they would have to pay them. If it was a murder case or something in the superior court, sure they’d take the time to do all that. But it’s not, and lawyers like me, that the one guy would never hire, all have enough trial experience to know that. Which again is why my client hopefully won’t be in a cage for the next year and a half, and that guy would be in prison for having an empty magazine in the back of his truck after paying some billboard attorney too afraid to ask questions…And just an FYI, when I started this thread, my biggest fear was that it in fact was a pre-1900 firearm, cause then all of those problems related to getting this information into evidence would be my problems.
That said, there is one very real surefire way that I can lose this case, that I’m not going to reveal because so far no one has picked up on it yet (meaning the lawyers or judge), and I don’t want to give it away. If this specific issue is flagged, this defense is toast and I’ll have to go with Plan B…