Sizing question,neck tension

[WEL]

I have some new Winchester brass 7mm. After sizing the inside of the neck is .280. What is considered a normal reduction in neck size for proper neck tension? Reason I'm asking , It took a good deal of force to seat the bullets. Much more than normal. When loading new brass I typically run through sizer to clean up the necks but do not trim( these were at minimum length already) or chamfer the necks. Never had issues before. The ammo I loaded was very accurate. I had one group that was .25 and another lot that was .5-.7. RCBS die.

 

[BoydAllen]

If it is accurate, that is all that you need to know. After you get some powder fouling inside those necks, the bullet seating force should be less. I do not recommend cleaning the inside of necks to bare brass. Just out of curiosity, what does you die's expander ball measure?

 

[WEL]

Just out of curiosity, what does you die's expander ball measure?

That is a good point. I will measure. I'm telling you that it was so tight I could feel the rings on some Barnes bullets engaging the neck as they were seating. I pulled a Nosler Accubond after it was seated and you could see where it lightly rubbed some of the copper off the jacket.

 

[BoydAllen]

One thing that you can do with new brass is to not FL size it, which in the case of a one piece RCBS FL die excessively sizes the neck before pulling the expander through, is to use an expander die and mandrel, of the type that are usually used to expand necks for turning. You can also dip the necks in some of this http://www.brownells.com/reloading/case-preparation/case-lube/imperial-application-media-sku749001166-33148-65118.aspx?cm_mmc=cse-_-Itwine-_-shopping-_-Imperial%20Application%20Media&gdftrk=gdfV21820_a_7c187_a_7c1021_a_7c749001166_d_749001166_d_20538 before expanding, or if you stay with FL die, before you lube, and then again (for new brass) before you add powder and seat.

 

[Catfish]

I assume that you are shooting them through a factory chamber and not a tight necked chamber since you did not mention od of the case necks. All I will say is " If it works, do not try to fix it."

 

[wapiti25]

Get some Imperial Dry Necksizing Lube, it is great stuff.

 

[LCazador]

Sounds like you may have some thick brass. Did you measure neck thickness? It could be your expander button too, check that dimension too.

 

[WEL]

Resized the brass and lightly chamfered the necks bullets seated with normal pressure. I never have chamfered new brass but I believe that was the issue. Expander ball was .282 and loaded case necks .309.