Load development with new brass

[mustang979]

So I took the leap and purchased 500 pieces of Lapua Brass for my 308 bolt gun. I was going to work up a small load to confirm my load, then work on sorting out neck tension (up until now I've been using a Lee neck sizing die where I cannot control neck tension, but I have grabbed a redding neck sizing die and some bushings), but imagine my surprise when I realized the lapua brass is already nicked sized, maybe too much so...

Is there no real case prep to do with the lapua brass when purchased new? It seems to be within spec for length. I'm assuming I'll have to fire all 500 pieces of brass before I can neck size and worry about sorting out neck tension on them? I feel like I am missing something obvious. do I just need to get an expander ball and resize them all?

 

[bsand]

If there are any bent ones then neck size. Otherwise load and fire! Check to make sure they cycle in your rifle before loading up.

 

[Alpheus]

Fire-forming is over-rated IMO. During the first firing, the brass will expand to fit the chamber regardless of how it was sized before, so what difference will a couple thou make? At peak pressure, the volume inside the brass will be the same, now matter how many times it has been fired.
For me, I also find new Lapua brass tends to have a little more neck tension then what I usual use, so I do neck size it out of the box. Other then that, I just run with it.

 

[titch--]

I always go through all of my new brass just to make sure.

A quick size and a chamfer/debur

 

[Hitzy]

Fire-forming is over-rated IMO. During the first firing, the brass will expand to fit the chamber regardless of how it was sized before, so what difference will a couple thou make? At peak pressure, the volume inside the brass will be the same, now matter how many times it has been fired.
For me, I also find new Lapua brass tends to have a little more neck tension then what I usual use, so I do neck size it out of the box. Other then that, I just run with it.

FL sized brass can be more then several thou smaller then the chamber (and double that in older milsurps), so your case/bullet will not be centered to the bore, it's going to have the bullet hitting the bore on a slight angle in mass produced factory rifles. Neck sizing fire formed brass helps correct this, you can also usually squeeze more powder into fire formed brass vs FL sized, which is helpful in compressed loads.
The actual accuracy difference may not be huge, but it does seem to be an improvement in my experience anyway by neck sizing fire formed brass.

 

[maynard]

Sorting by neck tension? Buy a .333 and/or a .334 bushing and be done with it. Lapua is so consistent you can add another 500 pieces 2 years from now and use the same bushing.

 

[bigedp51]

]FL sized brass can be more then several thou smaller then the chamber (and double that in older milsurps), so your case/bullet will not be centered to the bore, it's going to have the bullet hitting the bore on a slight angle in mass produced factory rifles.[/B] Neck sizing fire formed brass helps correct this, you can also usually squeeze more powder into fire formed brass vs FL sized, which is helpful in compressed loads.
The actual accuracy difference may not be huge, but it does seem to be an improvement in my experience anyway by neck sizing fire formed brass.

A full length resized case is supported in the rear by the bolt face and by the bullet in the chambers throat. Meaning the body and the neck of the case do not have any steering or alignment effect with the bullet and the bore. The average full length resized case is .003 to .005 smaller in diameter than the chamber diameter. The ejector is pushing the case forward in the chamber so the only part of the case touching the chamber walls is the shoulder of the case.

On the other hand a neck size only case is formed to the chamber and has more effect on aligning the bullet with the bore and cause "more" misalignment.

Below a cartridge case with .0025 variance in case wall thickness will cause the same amount of misalignment with the bore.



Below a Renington .223 case with .004 case wall variance and some of these Remington cases had over .007 thickness variations. So neck sizing these cases would have driven you up the wall trying to get tight groups.

On top of this the thin side of the case will expand more when fired and cause the case to warp and become banana shaped. This in turn will cause even more bullet misalignment with the bore and increase the group size. And if you do a little research on the subject more and more benchrest and competitive shooters are using full length sizing dies.

Below Kevin Thomas who worked at the Sierra balistic test lab and who is now shooting for Team Lapua USA

Bottom line, you are better off using a good full length die like the Forster FL die with the high mounted expander that does not pull your necks off center and induce neck runout.

 

[bigedp51]

Removed double post

 

[bigedp51]

So I took the leap and purchased 500 pieces of Lapua Brass for my 308 bolt gun. I was going to work up a small load to confirm my load, then work on sorting out neck tension (up until now I've been using a Lee neck sizing die where I cannot control neck tension, but I have grabbed a redding neck sizing die and some bushings), but imagine my surprise when I realized the lapua brass is already nicked sized, maybe too much so...

Is there no real case prep to do with the lapua brass when purchased new? It seems to be within spec for length. I'm assuming I'll have to fire all 500 pieces of brass before I can neck size and worry about sorting out neck tension on them? I feel like I am missing something obvious. do I just need to get an expander ball and resize them all?

Many competitive shooters just use a expander die to straighten the case necks and load and fire with Lapua brass.

Expander Mandrels and Neck Tension
http://www.accurateshooter.com/technical-articles/reloading/expander-mandrels-and-neck-tension/

Tools for Measuring Case Necks
Consistent Necks Enhance Accuracy
http://www.accurateshooter.com/technical-articles/case-neck-mics/

Also note if you have a standard SAAMI chamber and size the neck with a bushing die .005 or more smaller than its fired size you will induce neck runout. A custom chamber with a tighter neck and neck turning go hand in hand when using bushing dies.

 

[Hitzy]

Fully agree that if you are starting from a blank, best way to go is have a chamber cut to minimum specs and throated to your preferred bullet so you can FL size with minimum runout, minimum case stretch, and your desired OAL. I kind of figured we were on production guns with large sloppy chambers and excessive throats.
Most of my guns are milsurp, followed by hunting, followed by old target rifles. Lots of these are mauser based so there is no ejector pressure, some I would not even consider FL sizing for
..like the M1917/P14 as brass would be in pieces after 2-3 firings. There is actually a whole process involved in getting .303 brass fire formed evenly in the P14 by putting a rubber o-ring under the rim for the first firing....so further neck sizing improves brass life and accuracy. These get shot with match type bullets mostly as well and there is a definite improvement when neck sizing.
Even the old S&L M69 target rifles have pretty sloppy chambers...after firing a compressed load is no longer compressed. Also shoot match bullets through these with great results neck sizing.
Now the hunting rifles are a bit more modern, and probably have the tightest chambers out of all my rifles, some are as little as 2 thou over sammi min for headspace. They also see hunting bullets though, and FL sizing is used 99% of the time. Only the .223 gets neck sized as it doesn't seem to have any effect on hard chambering. It's the one gun I don't notice any real difference between neck and FL sizing on accuracy regardless of bullet used. I also shoot it the most, and neck sizing saves me a lot of time vs a lube/trim that goes with the FL size.
So really in loading for production guns, I don't really see a downside to neck sizing. In most cases it does improve accuracy, it always extends brass life, and it is faster when volume loading. I've never had a situation yet where neck sizing degraded accuracy over FL sizing, but that is all with factory/production rifles.

 

[Cleftwynd]

Alpheus is correct regarding volumes and pressures. Consider when developing loads with new brass that is not fire formed, is chamber volume - brass displacement. In other words, if a load of 55 grains of ###X powder develops 60,000 PSI and is accurate in your rifle, then the same charge will create the same pressure with new brass or fire formed brass as long as the brass is the same weight (read: displacement).

Combine this with what bigedP51 posted and you have what you need to know, you can start load development immediately with new brass.