Home Forums Reloading Varmint Rifles Why snapping off 25-20 necks

Hoping someone with more experience can help me. Been reloading off/on for 8yrs, but no expert, and first time with this case.

Once-fired 25-20 brass, which was formed by an online vendor from 32-20 and twice annealed. Lube neck interior with graphite, externally with imperial wax, pass it up into redding FL die (T7 press) with significant resistance but it goes, then on the downstroke the neck snaps off. Twice sent the die to redding to remove the neck brass, explaining what happened and including a few more cases which they returned sized.

Measured OD of the virgin (formed) is 0.270. The once-fired (Marlin 27S) measures 0.280. Unfortunately i lost track of the few cases redding returned so can’t measure those.

Begs the question, wtf am i doing wrong? What am i not seeing?

Maybe should sacrifice a couple with the expander taken out, see what happens?

Have you checked the thickness of the neck? Especially where it meets the shoulder?

This.

Gonna pay close attention here as I just ordered a MGM 25-20 bbl...

Took a minute to acquire a ball micrometer, sorry.

Measured neck wall thickness at four points around base of neck just above shoulder, five random once-fired cases, found the following. Remains unclear to me. You?


.0082, .0082, .0078, .0075

.0072, .0078, .0081, .0077

.0076, .0075, .0073, .0071

.0082, .0073, 0074, .0079

.0080, .0082, .0075, .0082

It would be informative to know how small the neck section of the die is making them.

You may have the size button adjusted too high in the die, i.e. it's too close to the neck sizing portion of the die. Then when withdrawing the case, you have part of the case neck still in the neck sizing portion of the die while the lower portion of the case neck is being forced onto the size button.

Try adjusting the size button a bit lower in the die, but not so far down it impacts the interior of the case.

Also try sizing a few cases with the decapping rod removed from the die. It won't hurt a thing.

I believe getting the expander ball too high in a Redding die is hard to do, but I haven't a 25-20 die to check out.

My first thought also.

Had a similar issue with .300 Blackout dies. There is a small range of adjustment of the expander ball location.

Try the Mule Deer trick:

1. Remove expander
2. Size cases
3. Replace expander and adjust it down so the spent primer is pushed out before the neck enters the neck-sizing portion of the die.

This does at least two things for you; first it expands the neck with the case held straight and second it reduces the stress on the neck which may be causing the snapping off.

(earlier I asked about the neck thickness thinking you might have the dreaded donut from necking down and pushing the shoulder back, are the necks thinner and more consistent closer to the case mouth?)

Revisited it tonight. Didn’t have an issue! Hopeful.

First, after cleaning the die returned from redding, i left the expander out. Like usual, first pass in a clean die i make sure it is covered in a thin layer of imperial wax. Passed it into press and there was markedly less resistance than in the past; let’s say, “normal” amount, whereas in the past the significant resistance was an “uh oh” moment. Lowering the ram there were no issues. Did a few cases. Next put the expander back in, and lowered it way down, the button just above interior bottom of the case. I pre-graphited the button, too, instead of relying on what the case neck interior supplied after dipping in graphited bead jar. Anyway, sending the ram back up and back was also uneventful. Then did some in one-step, the die assembled and stem left a bit loose. Running fine.

So. I don’t have a clear, one-variable-identified answer. My gut said as others did, that somehow was getting an interference fit between the die wall, brass neck, and expander as lowered the ram. And that may be, but the sudden overall decrease in resistance all around makes me wonder if redding was tired of me sending the set back and they polished it out or replaced it. No idea, but pleased either way thus far.

Awaiting arrival of hornady case comparator, then will do the rest of the once-fired pile. Shooting a couple old pumps, so hoping to set die to bump just .001-.002” and realize some longevity from this brass.