Hello, I'm looking at stocking up on self-defense ammo, and I've decided Speer Gold Dots offer a good balance of price and performance. Both the 55gr and 64gr varieties have been well regarded in the literature I've seen, however, I've yet to see any head-to-head comparison between the two rounds. Does anyone have this data available? The higher velocity of the 55gr round seems appealing, but the 64gr appears to be more widely used. Additional details: My primary AR-15 has a barrel twist fast enough to stabilize both. I have historical oddities (M16A1 clones) with 1:12 barrels, but I don't predict having to defend myself with them. Barrier-blind performance isn't a major concern, as I can't forsee any defensive situation where I'd need to shoot through auto-glass. If this is a flawed assumption, I would be happily corrected. Thanks in advance.