In the beginning, when I first started reloading for bottlenecked rifle rounds, I bought an RCBS case trimmer. Used a hand crank for turning the cutter and a series of collets for holding the case rims. While the trimmer seemed to do a good job, it was slow, very slow, and tedious.
After a while I started doing more high power shooting, and then acquired an autoloader or two, so the volume of rounds of brass that had to be trimmed increased. My first upward step was to convert the RCBS trimmer from hand crank to power drill. This did away with having to turn the crank, and maybe speeded the process up a tad, but locking cases up in the collet and then taking them out again was still tedious – and still time consuming.
So I began looking at alternatives. I briefly consider the Giraud, but the notion of spending as much for a brass trimmer as for a rifle that generated the need to trim brass slowed me down, way down. And, frankly, reports indicated that the Giraud was tedious to set up (by this time I was shooting multiple calibers) and to clean. I also looked at some of the devices that were designed to be chucked in a drill, but again reports were that these were tedious to set up and adjust (or change to a different round). And in both cases (no pun intended), I was dubious about trimmers that indexed off the case shoulder, versus indexing off the case head. (More on that in a moment.)
Well, my journey ended a couple of years ago when I stumbled on the Lyman Trim Xpress. This device was inexpensive (mine cost about $100, though I suspect they have gone up since), small enough as not to co-opt an expanse of bench space, and, most importantly, both quick and easy to set up and change rounds, as well as to clean. It also came with a set of bushings that covered all of the rounds I needed to trim, save one. (An additional bushing cost me a whole $10.) Trimming with the Trim Express is super fast: pick up a case, stick the neck into the bushing and push against a spring, and bang, the case is trimmed. At a generous 5 seconds per case, you easily can do 720 cases in an hour.
And, I learned the hard way, there is nothing wrong with trim indexing off the case neck datum.
Literally, the term “case length” means the distance from the head of the case (where it bears on the breech face) and the tip of the neck. And if case length is too great, the neck of the case will intrude into space in the freebore of the rifle’s chamber where it isn’t supposed to go. So I had always assumed – incorrectly, as things turned out – that indexing a trimmer on the datum was likely to yield cases whose overall lengths varied.
Datum indexing means that the trimmer fixes on the length, not of the case from head to tip, but of the tip to that plane intersecting the case’s neck whose diameter equals a standard value; in the case of .30-06 or .308 brass, the datum is .400”. A good trimmer will hold that distance constant. The only way that overall length will vary is if the distance from head to datum varies, and that should not happen if the cases are similarly resized before trimming. Each of the bushings that are used with the Trim Xpress is machined for a datum that is fixed by SAAMI standard for the particular round in question; you don’t even have to know what the datum is.
In fact, back when I was using the RCBS trimmer, I found that my trimmed cases varied in overall length by several thou. In hindsight, I think the reason for that is that the way the collets that clamp the rims work is by drawing the case back into the trimmer base the harder you turn the collet screw, and if either I used different clamping pressures or (more likely) my brass varied a bit in rim diameter from round to round, my as-trimmed overall length would vary. Since switching to the Trim Xpress, I find that all of my trimmed brass comes out within one thou in overall length. So: better result, faster, and easier. And an added bonus is that setup (and caliber change) is both quick and precise. Another bonus: cleaning the trimmer is a snap and requires no disassembly.
For the record, I don’t work for Lyman; they have no idea who I am; and I’m not selling anything. But the thought of a pile of several hundred rounds of brass needing trimming no longer drives me to watching TV instead, and my trimmed brass is all more consistent in overall length (which, in turn, means jump to the lands can be set and held precisely) than ever before. What more could one ask for?
