Yes, and possibly.
I should have been more exact in my original answer, though.
I should have said case length is less critical in revolver cartridges, which headspace on the rim.
In a semi-auto case, they normally headspace on the mouth so length is far more critical.
Now, back to your cases...
One good, quick, and cheap way to get all of your cases the same length is to get one of the Lee trimmers. It uses a cutter with a rod that bottoms out on a base into which you put the case. Does a nice job at quickly uniforming a bunch of cases.
As for how important it is to have all of the cases the same length, it really becomes more important when you start needing more crimp to hold a bullet in place against heavy recoil.
If you don't have all of the cases the same length, you can get quite a bit of crimp variation.
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