"Is there a good reason to have 33 bullets loaded in a handgun?" - Sam Stein
There have been repeated mentions that Giffords herself is a gun owner and "strong supporter of the Second Amendment". At least one news reporter has made remarks claiming that Rep Giffords ironically supported the right of the shooter to buy the very gun with which she was shot. Take from it what you will, but that doesn't seem to be the exact case. The gun used was a Glock 19 semi-automatic with an extended clip.
Here's a line item from the list of principles Rep Giffords indicated regarding gun control:
"Ban the sale or transfer of semi-automatic guns, except those used for hunting."
Does anyone really think that pistol is hunting gear? If not, you can't honestly claim Giffords supported the availability of that specific weapon just because she is a "strong supporter of the Second Amendment". While she has supported the right to own guns and owns one herself, she is on record for opposing specific guns, including semi-automatics.
Of course, we shouldn't necessarily base our policy on Rep Giffords' stance just because she was shot. And even if the shooter had not been able to get a semi-automatic, he might still have shot Rep Giffords. But we should be aware that if semi-automatic guns had been banned according to her stated stance -- or even if extended magazines such as the one that allowed him to load so many bullets at once were still illegal -- it would have made it significantly harder for the shooter to kill and injure as many people as he did without having to reload. After all, it was when his first magazine ran out of bullets and he tried to reload with a second magazine that he was tackled and disarmed.