The shorter length will cause no problems for you ...
MY question for you is why are you getting the various lengths ...
Are you using a trimmer with a collet to hold the brass ... if so the varying diameter of the rims of the brass control how far the collet is drawn into the trimmer body ...unless you are using a Forster trimmer ...it uses a slightly different collet ... if the rim is smaller in diameter the brass will be drawn farther into the trimmer and the length will be longer than say a larger diameter rim ... the larger the diameter the shorter the brass ... measure the rim diameter of a few brass and you'll see how much they vary ....
This is my solution .... I made a pilot that fits into the collet both small primer size & large .... the brass is held "dead center" of the pilot and the cutter stop ... I do have to use a rubber tipped glove to hold the brass from turning ... and you learn how much force to apply so the brass does not spin ... this method cuts the length from the actual bottom face of the brass to the cutter face .... it would never change unless you change it ... as I said "Dead Center" just like a lathe ...which that is what this type trimmer is a brass lathe ...
Here are a couple of photos ...
Here is the pilot ....
Here is how it works ...