After all these years of making 9mm ammo, I started having problems
with a load plunking and going into battery, at my last range session.

I took the pistol apart and started testing my "Dummy" rounds
and putting cases through the dies to check every possibility that
might turn up the problem.

When I got a 147 Berry plated RN to drop in and plunk at a OAL of
1.221"
I realized it was not the bullets fault.

I finally found the problem that was causing all the trouble.

Mt #2 die screw had worked loose and the result was that the case was not getting reduced enough at the mouth of the case.

This prevented the case to go 100% of the way into the chamber, by hand.

I am just glad that I did not load any new ammo, with this problem
to find out that it might have no worked later on.

Just a heads up for those, with well used units.

Have fun.

Just notice that this is in the ammo dept.
Please move to reloading, if needed, thank you.

I have found that any handgun round I load that fails the plunk test goes right back into the crimp die with another quarter turn down. Re-check, and if it doesn't plunk another quarter turn until it does. ALWAYS solves the problem.

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What could possibly go wrong?

Is 9mm a tapered chamber? are you sizing with a carbide die?

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"Don't Give Up the Ship"

Plus one to what DeplorabusUnum said. It should actually be a fairly easily fixed problem. When I’m reloading, I like to use a case checker to test every round before it goes into the plastic storage box to go onto the shelf or into the range bag. If they don’t plunk in the gauge, it’s back to the taper crimp or factory crimp die until they do.

Dad bought a nearly complete run of these gauges for pistol rounds over 30 years ago and they’re still working well. I recently added one from Lyman to check all of my straight side 32s. I hate to get all the way out to the range and not have usable ammo!

Froggie

All is good now.

With the die set at the right length for the cases, again

I re-taper crimped two boxes of ammo, and three magazines that held
the bullets in question and my loads made after my last range visit,
that had the correct OAL and taper crimps, that fed/ejected correctly.

No more loading for now, until I get to shoot my latest test loads, with
the Berry 124 Hybrid plated bullets, in a light standard loading.