I picked up Borderlands this week and am really enjoying it. I'm playing the Siren and use primarily Repeater Pistol and SMG weapons.

A little while back I purchased an Ammunition SDU from a vending machine. The SDU increased my SMG ammo up to I think 720.

Now whenever I visit vending machines that I come across, I still have the option to purchase an SDU for the same Ammunition. I figure you can just continually upgrade a certain ammo type and max it out (at an increasing cost), but the tooltip seems to be telling me that purchasing the SDU will increase my ammo to the capacity that I already have (720) and cost me $6000.

Is the tooltip misleading or is there actually only one SDU for each ammunition and they keep it in the shop for the sake of having it populated?

1 Answer 1


There are 6 levels of SDUs for every ammo type in Borderlands. Whichever level SDUs are available will be shown, but you will be unable to actually purchase an SDU that does not exceed the one you already have.

Also, ammo SDUs do not stack, and purchasing the highest level SDU will have the same effect as purchasing all of them, for a given ammo type.

  • Ah, interesting. When are the next tier of SDUs available?
    – Marty
    Commented Feb 16, 2012 at 22:11
  • It has been far too long since I played the game for me to remember, but I'm sure that information is available online.
    – kotekzot
    Commented Feb 16, 2012 at 22:15
  • All I know is the best SDU can be purchased at the vendor next to crawmerax
    – l I
    Commented Feb 16, 2012 at 22:26
  • 1
    In general, it's a good idea to hold off on buying Ammo SDUs for as long as possible.
    – MBraedley
    Commented Feb 17, 2012 at 12:54
  • @MBraedley why? You can never have too much ammo, and by the time the next level becomes available the one before it is trivially cheap. Also guns with regenerating ammo are incredibly rare. I'd buy Ammo SDUs at the earliest possible opportunity.
    – Keith
    Commented Aug 13, 2012 at 12:57

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