On trim length, if you measure case length of enough samples of your new, one lot and headstamp of cases you might be able to say they fall into 4 length groupings per 100. Simply segregating your case reloading that way will help your case length consistency, thus accuracy, or you might find that some trimming helps consistency of sub-lots even more.
That is, do not mix short and long cases. BTW do not mix headstamps either for similar reasons.
Now this might not matter much at foxes at forty yards, but you will see what happens on small paper targets at 50/100 yards. Groups open up !
I prefer to trim cases to make more cases of the 100 count batch the same, even though it may mean cutting some a bit shorter and maybe having a bit larger tolerance of case length. Get a Lee FCD die for 25-20 to apply crimps lightly but uniformly in straightening out the little M-die flaring needed to seat cast boolits to your chosen depth. You must use that M-die also, not that universal Lee die. They are not the same.
Since marlin chambers in the Classic 25 are a bit sloppy, try to cast above nominal diameter and maybe try sizing 258.5 or 259.5, but size somewhere for consistency and test results after you have slugged your bore.
Another aspect of reloading consistency is making sure cases are all of the same lot and headstamp because of powder capacity or volume. Starlines reformed, Remingtons, and Winchesters all hold noticeably different amounts of AA1680 for instance, and come new at different lengths, with different diameter necks. BTW, cast Boolits need as much scrutiny as the cases. As the lead pot heats up and you cast, temperatures change, casting sizes change thereby and similar when adding to the pot. Weigh a sessions production, cull bad boolits, and establish weight groupings. My highs and lows get recast, as my experience shows me that bullet quality is more important than most weight variances.
This makes you think of annealing. I believe you get better neck sizing consistency with annealing than without and that means the case neck's grip strength of the seated bullet. I already addressed split necks due to work hardening in case prep WITHOUT annealing in a post quite a while back. (visit Varmint Al's site on the annealing process).
Hope this information is helpful. Better shooting takes harder work.