Essentially, yes. At least depending on the semantics and how far you break things down. If you title the reason for failure as "failing to discharge the gun when required" then it's same-same. If you want to divide that into "disarmed" vs "mechanically inoperative gun due to not deactivating safeties" then it starts to change percentages. I don't know why, but shotgun manual safeties seem easier for people to remember to use, or are simply more ergonomic and get deactivated when the user means to, compared to handguns. Similarly, handguns don't get taken from the wielder very often. If that's a function of them being easier to retain or a function of how people are approaching their use (remember it seemed more handgunners remained stationary and waited for their target to approach them) I can't say. I can speculate, of course, but can't say for certain.
Regardless of weapon type, those who acted from ambush and used what I term "speed, surprise, and ferocity of attack" almost always won. It's the #1 predictor of who will win, more than weapon type, more than number of defenders vs attackers, more than which side had the "better" weapons, etc.
Those who postured and threatened but failed to act didn't fare as well. Those who gave away their position and/or got entangled didn't fare as well. Those who presented non-functioning firearms didn't fare as well. Particularly those who were subsequently outnumbered.