Neck Sizing versus full length?????

21 December 2004, 10:14

I have always full length resized and I was told at the range this weekend that neck sizing would improve accuracy since my brass is now fireformed for my rifle (bolt action).
I was also told the increased volume reduced pressures. Is this okay for bench shooting and not a good idea for hunting?
In my Sierra manual it says to backoff the full length die about 1/2 to 3/4 turn for a custom fit.
Comments from the pros are appreciated.

Thanks
Dwight

21 December 2004, 10:23

denton

No real pro here, but, if you're shooting a bolt action, and if you're not going to try to shoot the ammo in more than one gun, neck sizing has all the advantages.

I don't really think you'll see any significant change in pressure, but, you don't have to lube the cases, and they last a lot longer... the better accuracy claim is often made, but I've seen no data to support that.

I use the Lee collet dies, rather than trying to neck size with a standard die.

21 December 2004, 10:37

butchloc

I've heard this talked for 50years, As near as I can figure I've fired around 20,000 per year for about 50 years. I tried neck sizing, collet sizing, full length sizing, and a few others. Near as I can figure all work equally as well. Full length does not seem to detract from accuracy, but will allow you to use the same load in more than 1 gun. By the way my best group was a bit ago. .012 at 300 yds from a 22/250 full length sized.

21 December 2004, 10:47

Dwight

Thanks for the comments. I am always looking for information that may be an improvement to my knowledge base.
Looks as though I should not fix what is not broken since I get 1/2 to 3/4 groups in hunting rifles.

Dwight

21 December 2004, 10:49

vapodog

Quote:

I was told at the range this weekend that neck sizing would improve accuracy

another myth from the reloading crowd.

Yes...it could increase accuracy.....but it might be so insignificant that you never notice it. Case life would be a better reason to do this.

Quote:

I was also told the increased volume reduced pressures.

There is absolutely no basis for that statement whatever.

Quote:

Is this okay for bench shooting and not a good idea for hunting?

Actually neck sizing is fine for both but most hunters want the case to fit the chamber a little easier (looser)than a neck sized case. You be your own judge.

Quote:

In my Sierra manual it says to backoff the full length die about 1/2 to 3/4 turn for a custom fit.

Yes.....this means a custom fit in the means of head space only.....Your FL die will do some resizing of the case diameter doing this.....you just won't push the shoulder back to original specs.

True neck sizing dies are also available.....maybe someone else will explain them.....I've never used them.

21 December 2004, 10:53

Prewar70

If you are satisfied with your groups, don't change a thing. Benchrest shooters necksize only, and they may only size just enough to hold the bullet, which might be a 1/16th of an inch. They are only concerned with accuracy though and that's why they do it.

Hunters on the other hand, don't really want a tight case that they can't close the bolt handle on or fail while extracting, which is why most hunters full length resize.

Depends on what your after, each has its purpose.

21 December 2004, 10:57

kraky

You'll get lots of opinions on this. What sierra is recomending is commonly referred to as "partial sizing". You are still sizing down the sides of the case and the neck area but not bumping down the shoulder which makes your case fit the chamber better. I own collet dies, neck dies and full length dies. Collet dies do a great job of making "straight" ammo and I like that you don't have to lube the brass. If you want to experiment I would suggest that they will do the best job of neck sizing for a small investment. I do not hunt with neck sized ammo--it's fine at the range but should there be a little something on your case when it's chambered (for whatever reason) you could wind up with a stuck bolt or jam. I do not think you will see a reduction of pressure that is at all significant. If your full length dies are set for making good straight concentric ammo I do not think you will notice any improvement in accuracy in a normal hunting rifle. (Perhaps in a custom chambered long range/benchrest rifle where competitions are won by .10" it might pay.) These are my opinions and what I've found out over the years--this topic always causes controversy and many opinions come forth.

21 December 2004, 16:40

Duckear

Quote:

I...As near as I can figure I've fired around 20,000 per year for about 50 years...

that's 55 rds per day, every day.????????????????

22 December 2004, 06:39

Stonecreek

First off, let me say that I typically neck-size only. There are a few circumstances under which I might do otherwise, but none of them involve modern, solid-breached rifles.

Neck sizing CAN degrade accuracy if your die/press set up tends to cant the neck at an angle to the case body and thus creates a cartridge with significant eccentricity. In this case, FL or "partial full length" (oxymoron) sizing can make a more accurate load.

UNDER NO CIRCUMSTANCES will the slightly increased pre-firing case volume change pressures. It is the size of the pressure vessel (chamber) that limits the expansion of the brass and thus determines the net volume available for gas expansion and resultant pressure. Anyone who tells you otherwise is either uninformed or the victim of poor information. HOWEVER, if you are using a relatively slow burning powder which requires a compressed charge, the larger volume of a neck sized-only case can allow you to get just a few more grains into the case and thus reduce the amount of compaction. This can be critical for some calibers and loads.

By far the most important aspect of doing something other than "full length sizing" is to adjust the headspace of the cartridge for proper fit in the chamber. If you simply take an FL die, screw it down to bump the shellholder, and load the cartridge that way, it will be an accident if you don't have undesireably excessive headspace (with a rimless bottleneck cartridge). Whether you wish to only neck size, or to partial size, start with the die adjusted well off of the shellholder (.0875" or so), then progressively screw it lower using trial and error, so that the bolt closes on the resized, unfired case with the desired minimal resistance, indicating that the shoulder of the case is at least lightly contacting the shoulder of the chamber. In a bolt action rifle with a reasonbly round chamber, this is the condition you want your brass in to avoid a number of potential problems caused by overly-generous headspace (such as brass separation, excessive brass lengthening, misleadingly pancaked fired primers, etc.)

Let's review:

1. Accuracy may or may not change (but it is true that for the greatest accuracy potential, knowlegeble shooters prefer carefully neck-sized brass).

2. Pressures/velocities will not change.

3. Some high-volume loads need the slight extra brass volume provided by neck sizing-only in order to get the full charge of powder into the case (an unusual but significant circumstance).

4. Case life is increased and neck trimming is reduced by not overworking brass with excessive (FL) sizing.

5. Some extremely "generous" chambers may work much better with brass that is fireformed to them and not returned to pre-firing dimensions.

Loading for automatics, springy rear-locking levers, and other guns that do not have solid breaches MAY require more aggressive resizing than that which is adequate for a turnbolt that has the advantage of powerfully camming the cartridge home in the chamber.

21 December 2004, 22:30

Hot Core

Quote:

Looks as though I should not fix what is not broken since I get 1/2 to 3/4 groups in hunting rifles.

Hey Dwight, It might be a bit difficult to improve on those groups, irregardless of what method you use. It seems you are close to the point where significant gains in accuracy are created by lots of Trigger Time, custom barrels, Trigger Time, Match Grade bullets, Trigger Time, well tuned Triggers, Trigger Time, Loads developed based strictly on accuracy and more Trigger Time.

Quote:

I have always full length resized and I was told at the range this weekend that neck sizing would improve accuracy since my brass is now fireformed for my rifle (bolt action).

It "might" help to Neck Size and then again maybe not. The way to find out is to buy a single Neck Sizing Die and shoot some groups to see how well they do for you.

Every 5-6 years I'll re-run some Blind Comparison Tests of Neck Sizing to Partial-Full Length Resizing(P-FLR). So far, the P-FLR has always been a bit more accurate for "me". Someone else might just have different results with their rifles though.

Quote:

I was also told the increased volume reduced pressures. Is this okay for bench shooting and not a good idea for hunting?

It does indeed result in a very slightly increased "case volume", but not enough to concern yourself with.

As the other folks have mentioned, if your chamber is slightly out of round, the potential for having to fight the case into the chamber does exist. And someone above mentioned a bit of dirt with a Neck Sized case could be a potential problem, which I agree with. Same goes for a bit of dirt getting in the chamber with my P-FLRed cases.

Full Length Resizing does help avoid that issue. And if Dangerous Game is in the area you hunt, then you should ALWAYS Full Length Resize to reduce the possibility of that happening even further.

Quote:

In my Sierra manual it says to backoff the full length die about 1/2 to 3/4 turn for a custom fit.

That is fairly close to being how you P-FLR a case, ""BUT"" they left out that the bolt should close on the case with just a bit of resistance. That eliminates all Headspace issues, increases case life and (for me) increases your chance for improved accuracy.

The potential for increased accuracy with P-FLRing is due to the mechanical alignment forcing the CenterLine of the Bullet to become closer aligned with the Chamber CenterLine than any other method.

But, the only way for you to know for sure with your rifle and components is to run a Blind Test for yourself. Shoot a combined 15-18 shot group on a single target for the P-FLRed cases and another target for the Neck Sized cases. Have a buddy hand them to you so you do not know which ones you are shooting. If you shoot a "known flier" due to some distraction, call it and go mark it so it isn't counted in the final group.

It is going to be difficult to improve on those groups, but it is always fun and worthwhile(getting Trigger Time) trying.

Best of luck to you.

22 December 2004, 01:27

JAL

Quote:

In my Sierra manual it says to backoff the full length die about 1/2 to 3/4 turn for a custom fit.

Thanks
Dwight

Don't know if the FLS bit above had been explained enough.
If your rifle had some excess headspace, you should
wind up the fls die a bit, keep trying the case in the rifle
as you wind down. Best done with a "tight" case if you have
one. It should, or may, actually get too tight to chamber
for a while, then as the bolt eventually "just" closes,
your there. Perfect headspace for YOUR rifle.
Then fls/Neck size doesn't seem to matter much, you'll have
to try both. (I'm still doing both!!)
John L.

22 December 2004, 03:52

poletax

I neck size my brass after it is fired in my bolt guns.This works great for me since I only have one rifle per caliber.
When I get new brass , I full length size em.
Neck sizing doesn't seem to draw the brass out to where I have to trim as often.
Try both procedures and see what works for you.
Also , welcome to the forum. There is more knowledge here than any book you can buy.
And there are also links mentioned that you can go to and get even more tips on this insanity we call a hobby.

22 December 2004, 05:00

beemanbeme

To find the answer FOR YOU RIFLE is fairly simple. When you next resize some of your brass, resize say 10 using your current method. Then back the die out of the reloading press enough to put a nickle on each side of the die between the locking nut and the top of the press. (you don't have to readjust your die) Tighten things down and resize 10 more. Charge and seat as normal and you have your own field test.
I keep a couple of fender washers on my table with a hole in the center large enough for the die body to pass thru. I put them between the die and the press when I don't want to f/l resize.

22 December 2004, 06:59

Steve Malinverni

Vapodog,
my suggestion is to full lenght size your cases, without pulling back the shoulder.
Two are the ways, one screwing down the dies until the resizing sign on the collect arrives very close (almost touch) to the shoulder connection; the second ways is to maintain the actual dies setting developping a sensitivity on the moment when the dies is going to touch the case shoulder.
You will have the benefit of the neck size only and of the full lengh size at the same moment.
I hope that my suggestion has been sufficiently clear, otherwise I'll try to translate it better from Italian to English

22 December 2004, 07:24

vapodog

Steve.....thanks for the reply.......well written too.....I did in fact understand it.....your english is way better than my Italian I assure you.....

I used to spend lots of time at the bench trying to get little tiny groups.....today it's almost all hunting in one manner or another.......for that reason I full length resize everything.
Merry Christmas to you friend.

22 December 2004, 09:36

butchloc

duckear - I used to do quite a bit of competative shooting back a few years, and dueing that time I'd aveerage something over 50,000 per year. Would go out in my backyard or to the range every night and shoot til dark. Finally I quit when I found out that competitions ceased to be fun anymore. In fact 20,000 per year is probably quite conservative.