Bushing die issue

RevXP_09

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I'm trying to resize some ADG 300 PRC down to 7mm. New brass neck neck diameter is .333 a loaded dummy round after neck down is .312.

I'm using a .323 and .316 bushings in a Redding competition die. When I use the .323 bushing it sizes the case down from .333 to .316 not .323. Any reason as to why the bushings are under sizing.

If I start with the .316 bushing is sizes the case from .333 all the way down to .306 not .316
 
No I pulled the expander. If I leave the expander in case neck size doesn't change much at all.

Why would using a .323 bushing size it all the way down to .316?
 
I dont have a ton of experience with bushing dies, but I have seen it in FL sizing does where you take the expander out of it and the net result is a much smaller case dimension than one without.

I would not expect to get the dimension you are shooting for with only the bushing and not the expander.

Either put the properly sized expander in that die for you desired cartridge, or pick up a separate expander mandrel die and I bet you will like the size and concentricity you get out of that.
 
From my experience, I disagree that an expander should be needed at all, at least when referring to the OD of the necks. Expanders come into play immensely when inconsistent neck diameters are present. Maybe because my brass gets annealed frequently, but a .268 bushing yields me a pretty solid .268 OD. Over lubing maybe?? Something seems off.
 
I saw a recommendation once in a reloading book not to size more than .005 in a single step. If I stay close to that, I usually hit the diameter I want. I think the bushing makes a difference also. I don't seem to get as much oversizing with SAC bushings as I do with Redding TiN.
 
I had a similar problem where the sized neck measured a few thousandths less than the bushing. Many posters said that the bushing was probably mismarked. I called Redding and they said that it is not unusual for a neck to measure more or less than the bushing size used. It is caused by different brass compositions and/or brass temperament. They did say that the only way to properly measure a bushing is with pin gauges and that I could send it to them for an accurate measurement. I never sent it back but did order a different bushing to add to my collection. :D
 
I suspect if you size too much in a single step you will create a tapered neck with the smallest ID at the open edge of the neck. Annealing the neck prior to resizing would also help. Take some measurements along the neck to see if this is occurring.
 
I'm trying to resize some ADG 300 PRC down to 7mm. New brass neck neck diameter is .333 a loaded dummy round after neck down is .312.

I'm using a .323 and .316 bushings in a Redding competition die. When I use the .323 bushing it sizes the case down from .333 to .316 not .323. Any reason as to why the bushings are under sizing.

If I start with the .316 bushing is sizes the case from .333 all the way down to .306 not .316
I have actually done this: running a 7/300 PRC since 2020

You have a bit too much step down in bushings and should be using the expander in the process. Might want to try .328 to 321 and then down to 316 - it will put less stress on the brass. Additionally, the expander keeps the neck consistency throughout the sizing.

I found that I had to turn my necks after initial sizing - down to .0135 ending up with a 310 bushing for final loads.
 
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