1st time turning necks

GW Hunter

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Ready to do it on new Peterson brass. 1 question... Should I resize the brass with the expander ball or resize without and use an expander mandrel before trimming? Or does it matter?
 

swampbug

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Doesn't really matter as long as you have a tight fit when you neck turn.
Why are you neck turning Peterson brass? I am not saying the necks are perfect but just wondering what your thought process is.
 

nksmfamjp

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You want to FL Size, trim to common length, then expand on an expanding mandrel meant for getting ID to turning diameter, then turn necks.

At this point, you may need to size again to get neck tension right.

After sizing and trimming, I would look at neck thickness variation. Standard Peterson variation might be better than you can turn to accurately!
 

GW Hunter

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You want to FL Size, trim to common length, then expand on an expanding mandrel meant for getting ID to turning diameter, then turn necks.

At this point, you may need to size again to get neck tension right.

After sizing and trimming, I would look at neck thickness variation. Standard Peterson variation might be better than you can turn to accurately!
Size using expander ball?
 

dok7mm

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I recently turned several hundred pieces of Peterson brass. The base to datum was exact on each case, a rarity, so I just ran the turning mandrel without sizing.

Normally I would FL resize without the expander ball, then expand with mandrel in necks lubed with Imperial Wax.
 

nksmfamjp

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Size using expander ball?
I do, but I may slightly overwork necks. The point is to get the case shape right before trimming for length. I fl size.

The only sizing prior to neck turning should be with the turning system expander mandrel -on new/unfired brass.
If I don’t trim accurately, it is impossible to set up the stops consistently on my k&m tool. This is critical to just barely cut into the shoulder. Other tools may be different.

I recently turned several hundred pieces of Peterson brass. The base to datum was exact on each case, a rarity, so I just ran the turning mandrel without sizing.

Normally I would FL resize without the expander ball, then expand with mandrel in necks lubed with Imperial Wax.
How did you control trim length?
 

Mikecr

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I never trim until cases are fully formed and stable, which is usually 3-4 firings. Even then, I only trim if appropriate to do so.
A mouth stop is not needed for turning, as you're only touching the neck-shoulder junction to mitigate donuts with fire forming. There is no other reason to do it and it's never really accurate to a thickness setting because the cutter angle does not actually match shoulder angle.
Just sneak into a light touch, and it's fine.
 

GLTaylor

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Be sure to use an expander mandrel for neck turning - not a regular sizing mandrel. Regular mandrels will give you a tiny bit of slop in the neck. Turning mandrels are about 5 ten thousandths smaller. Sinclair sells both.
 
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