For all intensive purposes, Yes. Firearms in the DV, and for that matter most mortal items, rarely malfunction. They are used with propensity throughout the books, and they for all intensive purposes never malfunction due to magic.
First, pet peeve: It's "all intents and purposes."
Second, "all intents and purposes" is not "absolutely not." We have direct, observed evidence that magic does, in fact, cause firearms to jam.
Plus your ignoring that his is just Harry's assumption as to why the jammed. unreliable narrator etc.
Cripes I hate this "argument." "Harry doesn't know everything" is not license to disregard when he's talking about the things he observes directly and knows what he's talking about.
Harry knows how magic works. He can be relied upon to be right about the things he is observing actually happening. Just because it inconveniences your argument doesn't make it not true.
Seriously, this is like when certain people were arguing that the Red Court War wasn't even actually happening.
And your ignoring that we have not only dozens and dozens and dozens of accounts of no problem at all, but that Murphy and Dresden had a conversation about this. Specifically that Dresden's fear of autos is misplaced.
Right, because Murphy knows more about how magic works than Dresden.
Which is why, I presume, she has to ask Harry, multiple times every book, how magic works.
Sure is strange Carlos uses that glock all day long without a problem....
Carlos's glock is a semiautomatic. Not an automatic.
Yes, I know there are glocks that can be automatic, but Carlos's does not appear to be one of them.