Precision

There are times when one must speak with great precision.

When lives and fortunes are at stake being the main examples.

It's oft good to be precise even when such is not needed, because you will want to be taken seriously when it matters.

Guns are a place where the terminology is arcane and in some places appears to be contradictory.

.38 Special is not .38 Super and not knowing the difference can be embarrassing.  .38 Super is not .38 ACP and not knowing the difference can be fatal.

The difference between a clip and a magazine is not so vital.

Too many gun terms are creations of politics and are intended to influence the ignorant.  Assault Weapon is a good example here.

Using defined terms incorrectly because they are similar to the politically charged terms intended to sow such confusion is understandable for a layman, but unforgivable for an expert.  Assault Rifle ≠ Assault Weapon.

Making such a mistake inadvertently is understandable, but once the error has been pointed out; don't resort to the "but everyone else is doing it" defense or we'll have to use the "if everyone jumped off a cliff" rebuttal.

Repeatedly making such mistakes and haughtily declaring your rightness just makes you a laughing stock, regardless of the good will you may have garnered before becoming a paid shill.