Wilson case trimmer question

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blackhawk8

New member
I use a Wilson case trimmer for trimming. You have 2 different case holders, a case holder for new cases and a holder for fired cases. I understand that the new cases are slightly smaller than the fired cases. My question is when FL size the fired case doesn’t it go back to the original new size ? If so why would you need the fired case holder. Someone please explain this to me !

Thanks
 
Best guess is people who neck size. Trimming before FL sizing makes little sense to me. You could trim before sizing on straight wall cases as growth is not as severe.
 
It could be even though you full length size there is always a little bit of the base that the die doesn’t affect due to it being held in the shell holder. I’m just guessing of course.
 
IME, the new holders are too tight even for new brass. I use all fired holders and trim after FL sizing.

You can send in 3 brass fired or sized and they will make you a holder to fit.
 
I have lots of em--the Wilson trimmer is what I usually use; I wouldn't say my opinion is what Wilson might agree with--just what I've experienced. Basically, most cases have at least some taper to them, and the difference between fired and unfired might be enough that the holder doesn't get a good enough grip to keep the case from spinning or maintain good concentricity. So far I've never had a problem with any of the ones I have when properly matched to the case.
 
Did you ever buy a “new” holder?
Click to expand...
Yes. As a matter of preference I like the new holders simply because they are "post sizing" before doing the length trim. Some holders I've found can do "double-duty" for other cartridges, I found this out the hard way when I had to trim a case that there were no holders available for. I "seat" the case in the holder with a tap on a tabletop on the rim face and unseat it with a tap on the case mouth.
 
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Blackhawk8,

The direct answer is you misunderstood what Wilson means by "fired" case holder. You thought they mean fired and resized, but they actually mean fired and not resized, which is what the case body is when you neck-size-only. The reason for two holders is not just that the case body gets fatter during firing but that it is common for a chamber to have a slightly steeper body taper than a new or resized cartridge case does (for feeding reasons). A fired case has the chamber's taper after firing so a fired case body would not be gripped uniformly along it's body by the shallower taper of the holder for new and resized cases.
 
In theory, every case design has a taper….when fired, it is the same taper, but 0.001-0.003 oversized. With a normal to large taper, fired works well for fired, new and sized. With minimal taper like WSM, for instance, fired and sized/new cases cannot fit….they go too far in. So they make the next length smaller of the taper.

In general, fired works for all 3 until you get to minimal case taper cases.
 
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