Full length size vs neck sizing for precision

[shin95]

Hey guys, i'm pretty new to reloading for precision and just recently found a good load for my rifle.

I've done a lot of research, read a lot and watched a lot of videos. one thing has me confused.

When finding the perfect load for my rifle, I used new Lapua 308 brass. From my understanding, you don't need to full length size every time, but only neck sizing is necessary.
When a round is shot, the brass case expands in different directions. Wouldn't you want to full length size to bring that case back to specs?

If you neck size only, wouldn't the used brass have changed its characteristics and it wouldn't shoot the same as a new set of brass?

Am I missing something here?

Thanks in advance and putting up with my newb reloading question =)

 

[GhengisAhn175]

When you shoot virgin brass, you're going to lose some velocity but with proper load development you should still be able to get in your node window.

i would fine tune it with the once fired.

as far as FL vs neck sizing goes, it's your call. Eventually you WILL have to body size (other half of FL sizing). In my opinion the trend is generally get Fl sizing dies over neck/body. There's still a strong neck/body following but I bet if we took a poll FL dies would be ahead by a little.

In the end, it doesn't matter as long as you account for YOUR Procedure.

i recommend FL sizing each time. Whether you get a bushing die to control how much neck is sized Vs a non bushing is your call. Depends how much work you want to go through

 

[shin95]

When you shoot virgin brass, you're going to lose some velocity but with proper load development you should still be able to get in your node window.

i would fine tune it with the once fired.

as far as FL vs neck sizing goes, it's your call. Eventually you WILL have to body size (other half of FL sizing). In my opinion the trend is generally get Fl sizing dies over neck/body. There's still a strong neck/body following but I bet if we took a poll FL dies would be ahead by a little.

In the end, it doesn't matter as long as you account for YOUR Procedure.

i recommend FL sizing each time. Whether you get a bushing die to control how much neck is sized Vs a non bushing is your call. Depends how much work you want to go through

Ic. I was looking into a bushing die as well but didnt know how necessary it was. Guess ill focus on the whole 9 yards =)

 

[AuburnBLK]

You'll find guys on both sides of the fence with this one. I've tried both and can't tell a significant difference.

 

[jambau]

Shin95,

You are correct. The brass will expand in all directions. This is what forms the brass perfectly to your rifle's chamber. We call this fire forming. The theory here is that your fire formed case is now holding the bullet in better alignment with the bore of your gun. Neck size only, and you retain this benefit. Full length sizing squishes everything back to the "generic" dimensions. Also, depending on your dies, it could "flow" brass into the neck area which affects neck length and tension so you have to keep an eye on that too. There's a shit load of dies out there and we all have our opinions about them. I use simple Lee Collet Dies for neck sizing.

 

[shin95]

AuburnBLK

Thanks. If there is no difference, mind as well stay with neck size only.

jambau

Iv​​​​​​e heard of the lee collet dies. Is that the die that controls the length of the brass neck?

 

[FLIGHT762]

You cannot just neck size forever, at some point, you will have to F/L size. After you have to beat your bolt handle enough times to get a stuck N/O loaded case out of the chamber that failed to fully chamber. I learned my lessons about N/O sizing years ago. You can N/O size if you keep good notes on how many times the cases have been N/O sized. I don't N/O more than 3-4 times and usually only N/O when experimenting with loads. Most of the time, I F/L size when I want case to chamber easily 100%.

 

[Supersubes]

Lots of opinions on this. Most of us who started out chasing accuracy, had neck sizing recomended to us. In practice though, neck sizing doesnt work that well, simply because all brass doesnt behave the same, even with identical loads. If they did, neck sizers could simply choose to bump at a specific point because all their brass would have grown at the same rate. But thats not reality, some cases grow more than others so in a batch of cases, some chamber fine, some close hard, with the number of hard closing cases increasing with each firing. That is not a recipe for consistency. I would actually argue the fl sized case consistently centers in the chamber better than a neck sized case, with none of the associated stresses encountered with the random oversized round, that neck sizers never get away from. I was a neck sizer once, and many still believe the myth.


Buy yourself a concentricity gauge and see how straight your ammo is. Now consider that if the case walls were bearing hard on the chamber walls, the bullet is going to be scrubbing hard on the freebore of the chamber, since freebore is very close to bullet diameter, and your round has some runout. In a factory rifle, if you have any concentricity issues with the chamber or bolt face, that will produce an out of round fired case, both radially and axially. Unless that brass is indexed to go back in the chamber the way it came out, you'll close hard on it.