Packs made of sub-C cells actually make up a very small percentage of the airsoft pack market.
They're popular due to their performance benefit ratio. The smaller and thinner a cell gets, the higher the internal resistance.
By all means, go ahead and use AA, but there are better solutions available. There are a lot of packs made from full size "A" cells. AA is smaller. 2/3A (mini) is even smaller and has the highest internal resistance for any cell used for airsoft, but because the diameter is thicker than AA, it has less internal resistance.
The effect of internal resistance has been explained and described many times here over the years. But to put it in a nutshell, you want as little internal resistance as possible. The lower the resistance, the higher the current output capability, faster response times and higher ROF... without any voltage adjustment required.
If we could run car batteries, we'd all do it due to the huge performance benefits provided by it. But of course, the size is unwieldy and you'd sure as hell wouldn't strap it to your gun. We do our best to work within our limitations.
Last edited by ILLusion; September 13th, 2010 at 18:52..