Full length sizing die and neck tension

[bj139]

MC,
Good point on the AR chambering deforming the cartridge.

[LR1955]

Was playing around tonight on my reloading bench.

I have two bolt action rifles in the same caliber, one for hunting and one is for precision.

I use Hornady brass for the hunting one and LAPUA for the precision.

Tonight I was experimenting with my FLS die and measuring the neck tension it gave you. The results were interesting. An obvious statement would be that neck wall thickness affects neck tension. The point being I saw 2 very different neck tension measurements from 2 different brass manufacturers.

Now I also own a Neck Sizing Die where I can control the neck tension with the bushings but for some one with only a FLS Die, the different neck tensions could make a huge difference on accuracy.

Last point! For the hunting rifle I only full length size, for you hunting purists!

LRG:

Three potential reasons why you have different neck diameters after sizing. First is differences between brands of brass (thickness and metallurgy). Then differences in chambers at the neck. Then differences in loads (if you use different loads).

I have serious doubts that a FL sizer made by a reputable reloading die company would show huge differences in accuracy between brands of brass unless the brass is of questionable manufacture.

However, I do have bushing dies and yes, I do change bushings if a brand of brass has a significantly different thickness at the neck. I also pull a expander back through the brass, even when using neck dies. And with very well made bolt action match rifles as well as gas operated rifles. Just know that my expander button is barely touching the inside of the necks when I draw them back through.

I will not neck turn though. If a guy needs to neck turn, he needs to buy some decent brass.

LR55

[6mmintl]

After FL resizing (without expander ball) I anneal and expand neck for .001" less bullet dia. Neck tension for all makes brass.

[lrgrendel]

LRG:

Three potential reasons why you have different neck diameters after sizing. First is differences between brands of brass (thickness and metallurgy). Then differences in chambers at the neck. Then differences in loads (if you use different loads).

I have serious doubts that a FL sizer made by a reputable reloading die company would show huge differences in accuracy between brands of brass unless the brass is of questionable manufacture.

However, I do have bushing dies and yes, I do change bushings if a brand of brass has a significantly different thickness at the neck. I also pull a expander back through the brass, even when using neck dies. And with very well made bolt action match rifles as well as gas operated rifles. Just know that my expander button is barely touching the inside of the necks when I draw them back through.

I will not neck turn though. If a guy needs to neck turn, he needs to buy some decent brass.

LR55

LR55
Please explain how “Then differences in loads (if you use different loads).” Effect my neck sizes.

[LR1955]

LR55
Please explain how “Then differences in loads (if you use different loads).” Effect my neck sizes.

LRG:

A diet of hot loads will extrude the brass and work harden it more than much lighter loads. So, it will change its thickness as well as its ability to rebound. Same thing using fast powder verses slow powder -- with the same bullet. Faster powder may (may) put more stress on the brass than the slower powder.

LR55