Neck Tension

I've been having inconsistent results developing another load for my 6.5-300. It's been driving me little crazy.

My process is to size the case without an expander ball, and then expand the neck with the Sinclair expander die using the "E" (Expander) series. After bullet seating I do NOT crimp. I hadn't measured the necks, but, everything *should* work.

As I was readying another set of loads, I decided to check. I ran a test with the "E" series expander and the "T" series, which is supposed to be used for neck turning. Dimensions are in inches with a calibrated instrument. Measurements are made at the middle of the neck and the bullet is a 6.5mm 127 LRX.


It seems to me that .001" is not nearly enough with a 94 grain load of US869 and could certainly be contributing to inconsistency. I pulled everything I had loaded and will load again tomorrow with the higher tension.

What do you guys run for neck tension in high pressure, high velocity cartridges?

(Yes, I know the measurement is only a proxy for actual neck tension, but, it's what we've got!)

.002 minimum. Measure the expander and polish it with emery cloth and drill until you can get it.

.002-.003" but I never use an expander of any kind.

Same. .002-003.

Looser the recoil might change your OAL.

I do anneal regularly.


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I shot some more groups with the "new" neck tension. Things are looking up. Here's a 4 shot group with the 130 TSX.

To fine tune you can get expanders from here.

http://www.xxicsi.com/expander-mandrels.html

I use bushing and more set up for that and fine tune with those.

K&M also make them

https://kmshooting.com/case-neck-expand ... -kits.html

30-338":sspnu53q said:

To fine tune you can get expanders from here.

http://www.xxicsi.com/expander-mandrels.html

I use bushing and more set up for that and fine tune with those.

K&M also make them

https://kmshooting.com/case-neck-expand ... -kits.html

Click to expand...

I wasn't aware 20th century was making them that way. I'll have to decide if that's cheaper/better than getting a bushing die? Unfortunately, for a 6.5-300 Weatherby a FL Type S is a custom order.

Without turning the necks, I guess it is a case of whether I want my imperfections on the outside or the inside!

I have a question about neck tension should I resize them if I pull a bullet out them.
I had three loads that I felt would be to hot, so I have to take them apart. To size or not ?

1100 Remington Man":12xikqaj said:

I have a question about neck tension should I resize them if I pull a bullet out them.
I had three loads that I felt would be to hot, so I have to take them apart. To size or not ?

Click to expand...

I do. Anytime I pull them out I resize the necks.

Ok thanks. SJB358

1100 Remington Man":l6nbazhu said:

I have a question about neck tension should I resize them if I pull a bullet out them.
I had three loads that I felt would be to hot, so I have to take them apart. To size or not ?

Click to expand...

You do not have to resize after pulling bullets. Springback from pulling the bullets will be enough to hold the bullet and the amount of neck tension will depend upon how work hardened your brass is. More work hardened more springback, less work hardened like new or annealed less springback.

It may not be enough neck tension to satisfy your wants but the ID will be very consistent as long as all your cases have the same number of firings

Try inserting a bullet by hand and you should not be able to. A set of pin gauges will answer a lot of questions about actual ID