I'm not sure if my iPhone has automatically updated me to 5.1 (I have GunLog +P, so possibly not), so this may have been fixed already, but when I'm in the "ammo" screen and try to change the "quantity" field, the touchtone-phone type keypad that pops up completely covers the field I'm trying to change, and the keypad doesn't have a "Done" or "Enter" button. I have to click somewhere off the keypad to make it disappear before saving my changes.
Also, if I'm understanding correctly, the "quantity" entry in the ammo page isn't how much I currently have on-hand, it's a grand total of how much I've bought or made since I started using the program. That figure, while interesting, could probably afford to be buried in a report, and it would make checking/updating my inventory much easier if I could just make the quantity entry in the ammo page match what I currently have on-hand.
Overall, I'm liking the app a lot, which is probably why I'm nitpicking about the small things that still bother me, rather than just discarding the app entirely like I've done with others.