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"The Arcane Art of Case Trimming" by Worth Baldwin

Tuesday, October 31, 2023

 

The Arcane Art of Case Trimming

How to Make a Bad Task Less Bad without Busting the Bank (featuring Lee Quick Trim)

By Worth Baldwin

 

Ah, brass, wonderful brass!  For reloaders, it is the indispensable package of metallic goodness into which all of our expendable components must fit.

What makes brass so special?  In a word, malleability.  It is strong enough to contain the pressures, yet soft enough so our presses can squeeze it back into shape.  We must resize it because during firing it expands to tightly seal the chamber, preventing unpleasant hot gas from venting in our direction.  However, it never relaxes back to original dimensions.  Thus, we must resize.  Unfortunately, firing and resizing forces the metal to extrude forward because, whether in a chamber or a resizing die, that is the only direction it can go.  Repeated firing and sizing causes cases to stretch so much that rounds loaded with such brass will chamber very tightly, if at all.  Stretched cases must be trimmed to bring them back to correct length.  Fortunately, serious stretching is usually an issue only with bottle-neck cases.  I have never needed to trim handgun brass in over 50 years of reloading.  Handguns typically operate at lower pressures than centerfire rifle rounds.  Short handgun barrels allow the bullet to exit quickly, so the case is exposed to high pressure for a very short length of time.  In my experience, handgun cases split before stretching becomes an issue.  The same holds for 223/5.56 cases.  They have short necks, and in my experience almost always develop neck splits before they stretch sufficiently to interfere with chambering.

I hate case trimming.  To me, it is the most odious task in reloading.  Over many years, I have found a few ways to make this unpleasant task somewhat less objectionable.

Like most aspects of reloading, case trimming requires specialized equipment.  Many case trimming gizmos are available.  They fall into two broad categories: hand-operated and powered.  Some can be operated either way.  They may be bench-mounted, hand-held, or press-mounted.  Case trimmers are made by Lee, RCBS, Lyman, Forster, Redding, Hornady, Dillon, Frankford Arsenal, and many others.  Some typical examples are illustrated below (all images from Midway USA website - https://www.midwayusa.com/). 

 

 

It is beyond the scope of this article to describe and evaluate all the different makes and models of case trimmers.  I will therefore describe the types with which I have experience.

Perhaps the simplest is the original Lee case trimmer, which consists of a trimmer head, lock stud assembly to hold the case, and caliber-specific pilot to prevent over-trimming.  It is inexpensive and does the job, but is slow and literally painful to use.  It can be improved by chucking the lock stud into an electric drill, but clamping the lock stud down tightly enough to hold the case securely requires pliers, both coming and going.  The simple Lee trimmer is practical only for small quantities of cases.

I also own a hand-cranked Lyman trimmer.  As shown below, an adapter is available to allow it to be powered by a drill (similar adapters are available to motorize most other bench-mounted crank-type trimmers).  I don’t have the adapter, so I must crank away.  Hands and wrists tire easily. It gets the job done, but with great effort.  My Lyman trimmer is mounted to a board, which I can clamp to my bench, so it only takes up space when I need to use it.

 

 

I struggled along with the Lee and Lyman trimmers for years.  Then, the clever folks at Lee came to the rescue with the tools I currently use – Quick Trim.  The Quick Trim system consists of a cutter, which trims the case to length, into which a pair of spring-loaded blades are ingeniously nested.  One blade is pointed, to chamfer (bevel) the inside of the case mouth.  The other blade is convex, to chamfer the outside of the case mouth.  All three of these actions happen at the same time.  The intent is of course to save time by combining operations.  In practice, I find that most cases still need a little light finishing using a handheld chamfering tool.  Adjustment rings with click stops allow the desired case length to be precisely set.  The trimming assembly fits into the top of a caliber-specific trim die, which is in turn secured into a standard loading press.  Quick-trim dies look similar to other loading dies, as shown below.  By adjusting the die so that the press cams slightly over center, the case is held firmly in position during trimming.  Since the Quick Trim is press-mounted, it occupies no precious bench space.

 

 

The quick trim can be hand cranked, but works much more efficiently if chucked into a drill.  I have a cordless Makita that does a fine job.  I have Quick Trim dies for all the calibers that I routinely need to trim.

Of course, as mentioned earlier, there are more sophisticated self-powered trimmers that may be more efficient or easier to use than the Quick Trim.  But they generally cost from somewhat over $100 to over $400.  If money is no object (which it always is for me), take your pick of these super trimmers.  But for the rest of us, if you already own a good drill (preferably cordless), and a bench-mounted loading press, the Quick Trim will do a fine job without breaking the bank.  Quick Trim cutter assemblies generally sell for less than $27, and the Quick Trim dies go for around 13 bucks. 

I am glad I own a Quick Trim setup – several hundred oversize 30-06 cases are waiting in my workshop.

I hope your preferred trimmer works as well for you as the Lee Quick Trim does for me.

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Comments
RBCS Trimmer
10/31/2023 12:23 PM

I have a a RBCS trimmer and I was able to remove the handle and attach my cordless drill on end.  It makes it much easier and quicker when I trim my cases now.

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