I reload 6.5 CM and seem to make my concentricity worse when I size the neck then use an expander die. Is there a way to support the case in a die while running an expander die through? I have a Rockchucker Supreme press and a MEC press. Using Redding dies. Do I need to use an arbor press? Thanks
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expander mandrel case support?
- Thread starter patriotnation
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Next time I will absolutely make sure, good point. The new Lapua brass has a little bit out of round off the bat, not much at all but it gets worse when I expand it. I even changed from SS to carbide mandrel.
I am able to get about 1/2" groups at 100 but opens up at 500. next time to the range I will do 100,200,and 300.
I am able to get about 1/2" groups at 100 but opens up at 500. next time to the range I will do 100,200,and 300.
Are you talking about the concentricity of the neck?
Are you turning the necks?
I've find that the concentricity of the neck can (or does) get worse depending of what I do to the neck before hand. For example, when I size down the neck with a FL sizing die for my .308 without the expander ball, the neck is reduce to .328 from .343 and the concentricity of the neck is virtually zero (note too that I anneal my brass as the first order of my reloading process). Then when I run my expander mandrel through it to get to bring it to .334 to get my .002 neck tension, I'll get a runout of around .002 - .0025. When I'm slowly inserting the mandrel, I can get a little better results, but there still some runout that's induced by the mandrel. I have a FL sizing die that's been honed so that instead of reducing the neck to .328, it reduces it to .333 and then when I use the same expanding mandrel, I no longer get the runout. It was an issue I was trying to solve and apparently reducing the seating force keeps the mandrel from inducing any runout.
One of the other issues that I found will contribute to inducing runout when measuring it on the outside of the neck is that the variance in the neck wall's thickness is moved to the outside when an expander mandrel is used. So when one then measures for concentricity, that variance is often what is being seen as the amount of runout (or certainly contributing to it). I confirmed this by measuring both inside and outside of the neck at the same time. As good as Lapua brass tends to be, I found this was an issue with them and more so with brass that has much greater differences in case wall thickness.
There can be other issues, as in the alignment of the dies with the press. But it seems what I've described above tends to be the most common problem.
Yes I am talking about runout of the necks
I do not turn the necks
I do anneal each time now that I have an AMP
I forgot to write I have some new brass, some once fired and now have some twice fired. I was hoping I could avoid having to turn the necks.
I will definitely try to run the expander slower like you said. When I seat the bullets, I am now turning them(rotate) part way and then finish seating hoping that will keep runout down.
I know some benchrest guys turn their necks inside and out. I am loading for PRS and someday will get into more benchrest or f class stuff. I got the MEC press thinking the newer made RCBS rockchucker was not tight enough tolerances as it seems to have some play and the MEC has the floating shellholder grip.
Thank you
I do not turn the necks
I do anneal each time now that I have an AMP
I forgot to write I have some new brass, some once fired and now have some twice fired. I was hoping I could avoid having to turn the necks.
I will definitely try to run the expander slower like you said. When I seat the bullets, I am now turning them(rotate) part way and then finish seating hoping that will keep runout down.
I know some benchrest guys turn their necks inside and out. I am loading for PRS and someday will get into more benchrest or f class stuff. I got the MEC press thinking the newer made RCBS rockchucker was not tight enough tolerances as it seems to have some play and the MEC has the floating shellholder grip.
Thank you
Runout on the seated bullet is all you need to really worry about.
Of course runout on the neck is going to be worse after the mandrel. You just pushed all the irregularities to the outside rather than the inside, as with after your neck bushing.
Of course runout on the neck is going to be worse after the mandrel. You just pushed all the irregularities to the outside rather than the inside, as with after your neck bushing.
Yes makes sense. I thought maybe the case was bending at the shoulder oddly. I am still learning. Thanks
Yeah, and frankly, though I like to turn my necks, I don't think one needs to do so to get a good cartridge with little or no runout by using an expander mandrel. The expander mandrel shapes the interior of the neck in forming it to the mandrel. In doing so, the unevenness of the neck thickness is moved to the outside. So the inside diameter is going to be very concentric. And if the neck's axis has been aligned with the case body's axis (which will be done when running the case into a FL sizing die, but not necessarily one that uses a bushing), then the expander mandrel should maintain that alignment (assuming the expanding mandrel is free floating). Neck turning doesn't have a lot to do with being able to get cartridges with little or not runout on the bullet, though I feel it simply makes it easier to achieve. But neck turning does make a difference on how uniform the neck will release the bullet when fired. Which is a detail that benchrest guys, as you suggest, will feel beneficial, but not so much the other shooting disciplines.
Are you using the Sinclair dies/mandrel?
If so, are you leaving the cap slightly loose so the mandrel free floats?
If not, you might give them a try.
www.brownells.com
www.brownells.com
If so, are you leaving the cap slightly loose so the mandrel free floats?
If not, you might give them a try.
749011715 | Brownells
Brownells is your source for 749011715 at Brownells parts and accessories. Shop our vast selection and save!
www.brownells.com
STAINLESS STEEL NECK TURNING MANDRELS | Brownells
Sinclair stainless steel neck turning and expander mandrels for 17 through 50 caliber cartridges are turned from high grade stainless steel on precision turning centers. Turning mandrels are sized .002 inch under bullet diameter and expander mandr...
www.brownells.com
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Are you using the Sinclair dies/mandrel?
If so, are you leaving the cap slightly loose so the mandrel free floats?
If not, you might give them a try.
749011715 | Brownells
Brownells is your source for 749011715 at Brownells parts and accessories. Shop our vast selection and save!
STAINLESS STEEL NECK TURNING MANDRELS | Brownells
Sinclair stainless steel neck turning and expander mandrels for 17 through 50 caliber cartridges are turned from high grade stainless steel on precision turning centers. Turning mandrels are sized .002 inch under bullet diameter and expander mandr...
Yes I am and Yes it is free floating.
I use a Sinclair concentricity gauge as well. Thanks
Sounds good, thanks
I will keep trying it with expanding after sizing in order to get the same neck tension. I now have the Imperial dry lube that is with the ceramic spheres, previously I was only dipping the necks into the graphite alone which was probably not good.
