100%. "Small arms fire" is not going to hit an F35 at 2500 feet in the air with enough accuracy to not have collateral damage.

.50 BMG may pack a punch, but is it enough to go through titanium plating at 760 meters, upward while competing against gravity and drag? Obviously it would be enough if it were straight on (depending on the thickness of the titanium, but I would imagine the titanium around an F35 would not be very thick for aerodynamic reasons) but there are a lot of factors that would slow a large round like that down, and when speed goes down, penetrative force goes down.

I guess in theory it's possible, but while I don't have personal knowledge about being on the receiving end of that type of fire in an F-35, I would expect it to be noticeable if you were taking .50 BMG fire. Not just small "pings".

100%. "Small arms fire" is not going to hit an F35 at 2500 feet in the air with enough accuracy to not have collateral damage.

.50 BMG may pack a punch, but is it enough to go through titanium plating at 760 meters, upward while competing against gravity and drag? Obviously it would be enough if it were straight on (depending on the thickness of the titanium, but I would imagine the titanium around an F35 would not be very thick for aerodynamic reasons) but there are a lot of factors that would slow a large round like that down, and when speed goes down, penetrative force goes down.