Sort of. People have been accused or made to look bad for all sorts of things, and people have been made to look bad for doing the exact opposite as well.
You cannot really adjust your circumstances perfectly just in case you have to defend yourself.
The real claim is the use of a "Saturday Night Special" or "a gun really popular with criminals" or something similar with a mousegun. So rather than specifically the caliber it is the association of the gun with the criminal element the prosecutor goes for.
Traditionally mouseguns were the gun of choice for criminals (both the predatory variety, and the otherwise good citizen carrying illegally), because before concealed carry was legally common it was criminals and LEO that concealed firearms.
So the concealed carry market included a lot of criminals using them as a primary concealed gun, and LEOs that wanted a backup gun.
This was not specifically because they were buying more of them because they appealed to criminals, but a more complex reasoning:
Because a lot of mouseguns have been in low pressure calibers the material and strength requirements of the guns were much lower.
This typically allowed manufacturers to make and price these guns much lower than many service caliber firearms because they cost far less to produce and resulted in much less wear on the tools used to manufacture firearms.
This included both many revolvers, included various .38 special and below, and many inexpensive semi autos, some of which would become known as the "ring of fire" guns typically in .380ACP and below.
The result was both small dimensions and a lower price tag than most firearms. This combination made them extremely popular with low income segments of the population, which typically have higher crime rates and higher victimization rates (because the victims typically live in closer proximity to more criminals.)
This meant these guns were stolen more frequently from low income neighbors in burglaries, and due to their small dimensions subsequently carried by more criminals when available on the black market.
Hence small affordable firearms became associated with the criminal element. "Saturday Night Special" for example stems from an old racist term "Niggertown Saturday Night", and "Saturday Night special" was used to refer to guns inexpensive enough that they were commonly owned by low income blacks.
Later the term referred to any handgun inexpensive enough to be affordable for low income individuals of any ethnicity.
Contrary to the misconception that the term referred to low quality guns (though some are) it referred primarily to the price tag.
Legislation in various locations sought to create a minimum handgun price through arbitrary material and specification requirements. Such as preventing certain alloys, creating minimum melting temperatures for frames (which all modern polymer guns melt hundreds of degrees below) and other such restrictions.
But yes, there has been prosecutors that have pointed out that a firearm is a "Saturday Night Special", "junk handgun", "popular with criminals", "known to be so inexpensive you can just commit a crime and throw it away" and similar statements to make the defendant look worse to the jury.
The claim does not have to be true, just sound good or be believable enough to sway some jury members.
A DA does not go after someone due to the gun used, but rather attempts to reduce the defendant's credibility and tarnish their image in the eyes of the jury. Making the rest of the case easier to prosecute and reducing the benefit of the doubt the jury will give to the defendant.
