Egon
Epic Contributor
Length of bar really has nothing to do with the size of chain. In one way you are right, shorter bars _usually_ go on smaller saws and use smaller chain. However in the OP's case the same size chain will be used with both the longer and shorter bar.
I now have 3 sizes of chain, 3/8" 050
.325 ???
and some really small chain for my top handle 182T Stihl.
Harry K
Change chain size and you have to change the drive socket. Short bars are easier to handle than long bars.
For the OP I'd. Recommend a 13 in. Bar with narrow kerf aggressive chain. Less interference from other stacked logs when cutting to length.