i havent got a trimmer yet but was thinking, would it be a good idea to lightly sand the back of the casing ( back part by the primer ) to "square" it off befor setting it in the trimmer that way its seated flat and have less chance for run out ?
now wait dont get the wrong idea i dont mean like sand it as in rough sanding.. when i worked in the machine shop befor we ran a part under the indicator we would give it a light sanding to square it off.
befor we would run billets we would maybe sand them to take any burrs off so they would sit square in the jaws so i was just asking even if you would have said yes i would prolly not have done it