I feel like this is a question that should have a simple answer, but I have had a difficult time finding a clear answer one way or the other. Some sources seem to hint that you can brick a gun, like on p. 228 of the SR5 core rulebook:
The firing pin on an assault rifle might not work, but its bayonet works just fine for stabbing smug hackers.
But the closest DIRECT reference to hacking an opponent's gun seems to be hacking a smartgun system. On p. 233 of the SR5 core rulebook:
if your slaved smartgun is the target of a hacker’s Brute Force action....
So... can a decker acquire marks directly on an opponent's gun, and then do matrix damage enough to brick the gun? If so, then is this only possible if the gun has wireless on? Finally, if it IS possible to simply brick a gun and make it un-shootable... then why would anyone ever hack a peripheral (e.g. a smartgun system) when they can just brick the device?
Sorry if I'm nitpicking something that seems to be obvious. I just want to be clear as to whether this is or is not allowed, since bricking somebody's gun seems it would be a significant action in terms of the decker's relative power in combat.
EDIT: A follow-up question would be whether or not a decker can remotely fire an opponent's gun.