Anyone here using the Redding 357 SIG competition seating die? I had an interesting (painful!) experience with mine recently that I’d like to relate.
I’ve reloaded the 357 SIG for a long time. I added the Redding die a couple years ago, and it has always worked great for me. That was until yesterday, when I started playing around with cast bullets. The bullets are locally sourced 122g truncated cone/flat points, hard cast coated with Hi-Tech and sized to 0.356".
I adjusted the expander die for the increased diameter of the cast bullet and began setting the seating depth. The Redding die is awesome, it allows adjustments as small as .001”. Working down in increments, I would get to the point where the bullet was around half way to it’s final depth and then-bam! After the next minute adjustment down in seating depth (as little as .005"), the OAL would plunge from say 1.160” to under 1.10”. I fooled around for seemingly forever, and no matter what I tried it was the same end result. I pulled the Redding die and started using a Dillon seater, with the flat point seating stem installed. Problem solved, bullets seated normally without drama. Sooo, what’s different here? Noticing that the Redding die has a concave seating stem, and the Dillon a flat one, I assumed the seating stem was somehow the culprit and moved on.
Being the frugal reloader that we all are, not using the very expensive Redding die was ticking me off. Sticking with my seating stem theory, I searched the net looking for custom seating stems for the Redding comp die. The only thing out there is one made by Redding for use with VLD bullets in rifle calibers. That got me re-thinking my theory. Surely if the seating stem was the problem, I couldn’t be the only person EVER to encounter it? And if I weren’t the only person, surely either Redding or some enterprising individual would have designed a fix for it, right? Coffee in hand, I decided to take another look at things this morning.
I re-installed the die and replicated the original problem. I noticed two things. One, the seating process would go along normally up to the point that the bullet's grease groove went below the case mouth. Two, I could hear a "sproing!" noise coming from the spring inside the Redding seater, which also coincided with when the mystery seating depth increase occurred. As I contemplated the growing pile of test cartridges I would have to beat apart with the kinetic bullet puller, it hit me-too much case mouth expansion.
I re-adjusted the expander for absolute minimum, while still allowing the bullet to start square in the case mouth. And that was it-problem solved. The Redding die started behaving normally again. I was able to seat to the exact depth I wanted, and there were no sudden jumps in depth or “sproings!” heard.
Now remember that the issue did not occur with the Dillon seating die. Why not you ask? My theory is that, when the bullet grease grove (empty, as these are coated) got below the case mouth, case neck tension dramatically dropped. The “sproing!” I was hearing was caused by the spring loaded seating stem suddenly moving forward and forcing the bullet deeper into the case. Once the bullet reached a certain depth, the full diameter forward driving band made contact with the case and, proper case neck tension restored, stopped it from seating any further.
I’ve been shooting and reloading the 357 SIG off and on since 1995. As such I’m all too familiar with it’s finicky case neck tension, but this was a first for me. Hopefully some future reloader having the same problem will Google his way to my story here
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