Neck sizing.
 

I have a lot of brass that has been fire formed to my 7mm. I am looking at neck sizing alone since the ammo would only be shot through the same rifle. How many reloads would I be looking at getting and those of you who neck size, do you see accuracy improvement. Thanks. HD.

I did that with 7mm Rem Mag....here's the deal....
. USING NO POWDER or PRIMER, build a dummy round. Use NO powder until ur
Satisfied you have a winner and are prepared to load live rounds...

. First firing fire forms the case to yr chamber
. Adjust ur neck sizing die to size as little of the neck as possible...just enough to hold
The bullet AFTER you trim the case. In my rifle, would size about 1/2way down the neck
then trim back to a a few thousandths from max.
. Adjust ur seating die carefully...when you build your load, u want the oal as long as
possible. Back the seating die so the oal is over long. Use a match or lighter and blacken
Your bullet. Run it thru the action...do not force the bolt closed if iit won't go ! That means the oal is too long. What ur looking to do, is to look for the marks the barrel makes
On ur bullet when you chamber it...if u see marks, re-seat the bullet a couple thousandths deeper in the case and re blacken it. Repeat this procedure till you see no marks on the bullet after you chamber it.

What you've done at this point is to fire form tour case to chamber dimensions,
Seated the bullet deep enough in the case neck to be held in place but not to adversely
Affect it's performance with too much 'hold' from the case neck...and your cartridge is
Just short of the overall max length to shorten the jump from case to throat to rifling.

Use this dummy to set ur dies and lock em down for consistency. Next, load some live
Rounds. Be very wary for signs of high pressure when you fire ur reloads...start with lo powder charges ...remember....neck sizing takes a lot of the 'slop' out of ur ammo. Consequently, by pushing the max dimensions on ur ammo, it is natural that chamber
Pressures WILL rise. So start at minimum charges and work ur way up to where you get max accuracy with no signs of hi pressure.

I get 3/4 groups (5 shot) using this method in my Remington in .338wm...

You may get 2 or 3 reloads like this before you will need to full-length resize...you'll know it's time when the fit gets tight when u chamber a round.

Neck sizing will give you better accuracy and longer case life. However, even fired from the same rifle those cases may take some effort to chamber. Not a problem on the range, but in a hunting situation where a quick action cycle is necessary it may cause you to lose your animal.
Weighing the odds, I go with full length sizing. But that's me.

Broncos right...but you need to weigh what you want your results to be...a potential big jump in accuracy ( much more than you can hold in a hunting situation, but lookin nice from the bench ) or quick chambering ammo. I've never personally had to deal with tight chambering problems, but I only go two times before I go full-length on the sizing die. Too much neck sizing will also get you neck splits when the brass gets fatigued and needs annealing....

Not only do I neck size exclusively, I do it with a Lee Collet die, which greatly reduces work hardening (and the resultant splits). I can get 20 or more reloads with even heavy loads (although you still need to trim for OAL every so often).

I use a neck sizer only die, and anneal when needed. I trim to chamber, and only full length resize when absolutely necessary. Your brass will last indefinately if you work it as little as possible.The better the fit, usually, the better the accuracy. The shorter the space between the mouth of the case and the bore, the less the bullet is deformed when it leaves the case.