My gauge must be slightly off because for a start the orange sleeve is an inch longer than the pattern suggests, and 1.5" longer than my black sweater. Also you will notice that orange sleeve is much narrower than the black one. It is at this point that I need to realise that these two sweaters are not the same, no matter how much I might imagine they are related.
- The black one is made of very old and threadbare chenille: it is limp and floppy. The orange one is made of new, sturdy and thick wool with lots of depth and spring. A sleeve as wide as the black one in that orange wool would be too big and heavy to wear, I think.
- The black one has set-in sleeves but the orange one is going to be a raglan. I think you have to plan extra armhole depth with set-in sleeves, which could account for the underarm depth difference.
So I shall not worry that they don't look the same. However, that orange sleeve is still an inch longer than the pattern says, which is a problem.
- I could reknit the whole sleeve, resetting all the inreases, which would allow me to have the full 48 sts when I reach the new, shorter length.
- I could reknit the whole sleeve on smaller needles to correct my row gauge.
- I could just rip the sleeve back to the right length and suffer having a narrower circumference and fewer stitches at the point of the sleeve reaching the underarm. I haven't thought this through yet and need to check the pattern to understand the likely implications.
- I could leave it the length it is and turn the cuffs back.
- I could put it on a length of waste yarn and try knitting the body to see if that helps me know what to do about the sleeves.
I'll let you know how I get on.