Please fill me in on Neck Sizing vs Full Length Sizing.

[evan price]

In my Rem 700 PSS .308 I first full length resize the brass to get it to "zero" then trim to minimum.
Shoot it in the rifle, and keep the cases segregated (easy, since I've been shooting LC MATCH brass).

Then on I use a Lee Collet neck die to resize. Keep going that way until the case eventually starts getting harder to close the bolt on. Then it gets FLR'ed again. One advantage (to me) is the brass lasts a lot longer this way than it would from FLRing every firing. Less work hardening. Of course, annealing will help this too.

 

[Slamfire]

Slam are you quoting me?
I believe I said
Quote:
move the shoulder back .0005

Count the zeros

Jimmy, I was not quoting you or making you "the bad" example. I did not count the zero's either, .0005" setback would be fine, but I doubt my measuring equipment is reliable at ten thousandth measurements.

A good rule of thumb is that cases are not expected to stretch more than .006" without rupturing. That is where the .006 came from.

By the way that piece of steel in the picture may not be same size as my peice of steel I call a chamber.
Jimmy k

I stole this picture from someone, and now I have forgetten who.

But I am certain that the picture taker did the same thing I did with my Wilson gages, that is drop chamber headspace gages in the things.

My Wilson gages correspond exactly with chamber headspace gages. The lowest level is exactly the Go gage, and the highest the No Go gage.

I have gaged most of my rifles. The factory bolt rifles with matching bolt and serial numbers, if they are push feed with those blasted in bolt face ejectors, I just assume that the factory got the head space correct. It is too much of a fuss to remove the extractor and the ejector. I do have the tools for M1's, M1a's, and AR's but not M700's or M70's.

So, if your rifle is correctly headspaced, then the gages will work. You can still drop a fired case in a Wilson gage and determine the headspace and adjust your dies accordingly.

 

[JimKirk]

Slam
I didn't mean to sound like I was ticked or anything, but you did quote my saying that I had loaded the 25/06 cases many times and them went on to say what you did about the .003 & .005 numbers. I had assumed that by doing the quote that I said what you said.


But my statement about the Wilson case gauge or any other gauge is just that a gauge.
But the only gauge that really matters is the chamber on the gun I am loading for at that time. The topic of the thread is about neck or FL sizing as related to the OP and his one gun. While the "gauge" would be ideal if he had five guns of the same caliber, all that matters is "that" one gun.

So, if your rifle is correctly headspaced, then the gages will work. You can still drop a fired case in a Wilson gage and determine the headspace and adjust your dies accordingly

But if it is not, what good is gauge other than to let you know that you gun is out of specs? That 25/06 chamber of mine is "long", it will fire factory ammo, but it is long none to less. If I were to use the gauge to set my dies, my brass may last three shots, maybe.

Maybe I'm beating a dead horse or maybe I'm just talking to myself, again.

Jimmy K

 

[woods]

I think you are right on Jim. The go-no-go gauges will only tell you if you are within specs or out of specs. A Hornady headspace gauge or the Innovative will give you numbers to work with so that you can set your shoulder at .001" or by interpolating between the lines to .0005".

The go-no-go's are even less useful on belted cases since they measure the headspace on the belt and not the more important measurement of head clearance at the shoulder on the datum line



I have never seen the usefulness of a go-no-go gauge other than when the gunsmith is reaming the chamber.

 

[JimKirk]

Woods
I have a Mitutoyo 2910S-72 indicator that will read .0001, a gift from my wife's uncle who worked at NASA and later at Savannh River Site. Sometimes it is good to have in-laws.

Jimmy K

 

[Bart B.]

Sierra Bullets full length sizes their cases used to test their bullets for accuracy. They've got best accuracy doing this for their test barrels with standard SAAMI chambers since the early 1950's. Instead of regular full length sizing dies they did years ago, they now use full length Redding Full Bushing dies for cartridges they're available for and Redding standard full length dies for the rest. I doubt anyone shoots their bullets more accurate than they do.

The smallest groups with more than 10 shots at all ranges beyond 200 yards I know of have all been done with fired cases full length sized. And in one test full length sizing one fired Winchester .308 case then shooting it at 100 yards 57 times, all shots went inside 3/10ths MOA. Virtually all high power match rifle records and winning scores are made with cases so sized. Even the benchresters are moving towards full length sized cases. There's even evidence that compared to neck only sizing, proper full length sized rimless bottleneck cases fit the chamber better at their front end aligning the bullet more precise to the bore when the round's fired.

It's important with full length dies to size fired case body diameters down and set fired case shoulders back 2 to 3 thousandths of an inch. And dies without those darned neck-bending expander balls. Just deprime and clean fired cases before lubing and sizing them.

If new, unfired cases can produce better accuracy than neck only or partial neck sizing, doesn't it make sense to resize fired cases down to about new case dimensions? But then if one doesn't full length size their fired case the best way for accuracy, then neck or partial neck sizing will produce better results.

There's a popular belief that full length sizing reduces case life. But folks who use proper dies for .308 Win. cases get several dozen reloads per case with max loads. I've got as many as 45 but ran out of powder used in that test. Never annealed a case neck, either.

 

[Bart B.]

navyretired 1 comments:

Bump sizing is very popular right now in bench rest world, but I don't know why

The reason's been known by top high power rifle shooters since the early 1960's regarding rimless bottleneck cases. It has to do with a small amount of clearance needed at the shoulder to do two things.

One is to prevent the bolt binding on the case head when it's closed if sized case headspace is any greater than chamber headspace. This usually twists the bolt head to a position other than where it would stop at when it doesn't bind on the case (especially with unsquare bolt faces). With it at a slightly different position, super accurate rifles will put the bullet at a different spot because the barreled action whips and vibrates a bit different. The bolt head has to be in exactly the same place for each shot. Some 'smiths for benchresters fit bolts so tight to receivers to ensure they're in the same place for every shot, a fat microbe on the bolt would prevent it from opening.

The other reason is how the case gets positioned at its front end in the chamber. With so many benchrest rifles' chambers cut pretty tight at their shoulder diameters, any interference at that point by a chambered round will cause accuracy problems. As there's no such thing as a perfectly round case or chamber at the shoulder, a case whose maximum shoulder diameter's at the minimum chamber shoulder diameter may offset the case neck in the chamber neck a tiny bit. If there's enough misalignment of the bullet to the rifling, accuracy will degrade a bit. With a thousandth or more clearance between case and chamber shoulder, there'll be no interference. This is one reason why proper full length sized cases typically shoot more accurate than neck only sized ones.

With a bit of clearance at the shoulder diameter as well as headspace, the case shoulder's free to seat perfectly centered in the chamber shoulder when the firing pin smacks the primer and setting the shoulder back a few thousandths before the round fires.

 

[Walkalong]

One is to prevent the bolt binding on the case head when it's closed if sized case headspace is any greater than chamber headspace.

Exactly, and a much better answer/explanation that when I posted - "At the pressures we were operating at you simply must bump the shoulder a hair each time".

Outstanding post all the way around Bart.

 

[duck911]

Question for you all:

If a fella is shooting brand new brass right out of the bag, could it take a few firings for the shoulder to move forward enough to even be able to partial FLRS?

I have a 17 Fireball and when measuring my brass compared to unfired brass, I found that my shoulders barely moved forward. Should I just shoot until I finally do have a crush fit, then PFLRS until the end of time?

thanks,

--Duck911

 

[Chamacat]

Not to take away anything from this thread...I have read somwhere..I'm thinking a reloading manual that for 30 caliber and above it is recommended to full length resize every time...I would think that on "Magnum" cartridges that full length would always be performed..I'm knew to this also...Thanks

 

[Walkalong]

If a fel

la is shooting brand new brass right out of the bag, could it take a few firings for the shoulder to move forward enough to even be able to partial FLRS?

No, it just often times isn't as blown out as much (after retracting when the pressure subsides) the first time as it will be the second.

 

[JimKirk]

I want to add something for you guys who shoot Belted Magnum Cartridges(BMC). If you Full Length Size(FLS) and your chamber is longer than what your die has sized your brass to, then you have created artificial head space. Because the belt is what actually(in this case) head spaces the cartridge. But because you may have moved that shoulder back .005 or more, depending on your die, you cases will stretch between the belt and shoulder, usually this happens right above the case head. If you get three reloading out of a case you'll be lucky, and you may get a case separation and that ain't good!
This is where Partial Full Length Sizing(PFLS) comes to play it best game. If you PFLS so that the shoulder and the belt touches the chamber at the same time, you will have a perfect head spaced cartridge. Even if you move the shoulder back an additional .001 less you are much better off than FLS.
My old reloading mentor showed me how to smut a case with a candle so that you could tell exactly how much you've move that shoulder and if the belt is touching. It is simple, smut the belt area(don't get the case too hot) and smut the shoulder area, leave the middle of the case blank so you can handle it. Try it and let me know how it works, you don't need a gauge of any kind and it tell you the truth....How that case fits MY chamber! Oh by the way, It works for non-belted cases just as well! That is why I have such a distaste for belted rounds too! Have you noticed that the new rounds don't have belts!

Jimmy K

 

[twofifty]

Not adding anything here but to say 'thanks all' for a very useful discussion that helps me understand the 'why' of what I noticed was going on.

I started out FL sizing, then went to NS only...till the cases wouldn't easily chamber, then found out about PFLS i.e. bumping. The latter gives me consistent bolt closing effort and consistent match results.

 

[TexasShooter59]

I wanted to say that I really have appreciated this discussion, also. I am hoping to finally get started reloading soon and this is something I needed to know about to reach my goals. Otherwise, I was just going to neck size my existing brass.

 

[fguffey]

"I consider setting the shoulder back .003" to be full length resizing. Setting the shoulder back .006" will cause case head separations".

"A good rule of thumb is that cases are not expected to stretch more than .006" without rupturing. That is where the .006 came from"

I do not know, again Hather reamed a 30/06 Modified chamber, he moved the shoulder forward .125 thousands and fired 30/06 ammo in the chamber thinking the case would separate, for his trouble he got a case fire formed to the 30 Hatcher modified/06, but that was a different set of rules.

Again 8mm57 ammo has been fired in an 8/06 chamber, none had case head seperation, although the shoulder bacame part of the case body and part of the neck became part of the shoulder the case when extracted was nothing more than a short necked 8/06.

The shoulder did not move, part of the neck became part of the shoulder and part of the shoulder became part of the case body.

F. Guffey

Not sure where these numbers come from as in .006. If I owned a set of dies that moved the shoulder back .006 thousands I would get my money back, my press, die and shell holders are designed to size a case to minimum length, that would be .000 as in .005 shorter in length from the head of the case to it's shoulder than the chamber (go-gage size) length from the bolt face to the shoulder of the chamber, and then there is all that press flex? So full length sizing is sizing to minimum dimensions..and there is all of these 'BUMP' precision adjustments as in bumping the shoulder back .0005, how do you do that? As in adjusting the die to the shell holder in the press with 14 threads per inch without a degree wheel or a feed index in thousands.I do that, I use the 'Companion Tool To The Press Tool' the feeler gage, Elmer Fudd has trouble with the letter 'R', hand loaders can not say FEELER GAGE. I use the feeler gage as a standard and a transfer.

F. Guffey

 

[ranger335v]

"Please fill me in on Neck Sizing vs Full Length Sizing."

That could easily take a chapter in a book. Ain't gonna do that so I'll get to the bottom line; Sometimes neck sizing helps, sometimes it doesn't. Try it.

The Lee die is likely the best neck die available for factory chambers.

 

[Dannix]

I've been following this thread on again, off again...

Ranger, could you provide a link where such a chapter is posted or printed?

 

[Roamingdoc]

OMG! Wow.... I stumbled across this thread while "trying" to improve my "new" reloading skills (errr, lack of them?) and decided I need a PhD in "something" to comprehend what seems to be great information.
Bart B says "But folks who use proper dies for .308 Win. cases get several dozen reloads per case with max loads." -
I'm shooting a Rem 700 (three years old, 1800 rnds) VLS (heavy barrel) completely SAAMI. The stock is AI. I shoot off sand bags usually prone. Scope is Leu 6.5x20 (old eyes).
T-7 is my press... been using RCBS dies - but reading this I'm wondering if I can drop lower (regularly shoots .75MOA with careful mechanics) without changing the gun, just the methods of my reloading.
How does one go about 'determining' the "proper dies?" Should the Redding 'bushing' based dies be used. I don't see anything else comparable to them but I don't know how to use them exactly either (not owning a set) and so I ask...
I've been using a standard Digital Caliper and don't own anything that measures runout, etc... should I?
Thanks...

 

[USSR]

How does one go about 'determining' the "proper dies?" Should the Redding 'bushing' based dies be used. I don't see anything else comparable to them but I don't know how to use them exactly either (not owning a set) and so I ask...
I've been using a standard Digital Caliper and don't own anything that measures runout, etc... should I?

If you want to take it up a step, IMHO, Redding bushing dies and some measurement tools are well worth it. First the tools. While there are many, the 3 that I find essential are, an RCBS Precision Mic for measuring your case headspace, a Hornady (formerly Stoney Point) OAL Gage for measuring your rifle's boltface to leade measurement, and a tool for measuring your reloaded cartridges case base to bullet ogive length (for adjusting your seating die). I like to seat my bullets .010-.012" short of the leade if the magazine allows, and do all my load development with a fixed COAL and varied powder charge weights. Now, regarding the bushing dies. The beauty of the bushing dies are many fold. First, you do not overwork your brass. With regular dies, you deliberately reduce the neck down to below what you want, and then pull an expander ball thru the neck to bring it back up to where you want it. Pulling the expander ball thru the neck can change the case headspace, as well as introduce runout by making for a less than straight neck. With a bushing die, you reduce the neck diameter to exactly what you want by selecting the appropriate size bushing, and it can be varied (something you can only do if you have several different size expander balls available with regular dies) according to the brand of brass you are using, or the application (autoloader or boltgun). Another benefit is, if you go with the titanium nitride bushings, you do not need to apply a lube to your case necks. I use a Redding body die in combination with a Redding bushing necksizing die to FL resize my brass. Two distinct operations to FL resize my brass, but I like the control it gives me. Hope that helps.

Don

 

[Roamingdoc]

Thank you Don... I am digesting it.
I was about to buy a digital headspace gauge from Larry Willis and I think it does about what you were suggesting.

It seems that (1) everyone is suggesting FL sizing for better accuracy and (if done correctly, like with a bushing based die) adds longevity to the case. I will have to learn how to use the bushing setup.

I was under the impression that 'very fine' variances usually only helped in rifles with expensive aftermarket barrels but that does NOT seem to be the case (?).

I think I'll sell the RCBS dies and get the Reddings set. Still learning, THANKS!

 

[243winxb]

Redding Type S FL sizing bushing die will size the case in 1 operation. Use of the expander button is optional. As for adjusting shoulder bump, set up die with a shim between the shell holder and FL die. Adjust till bolt action will close.

(regularly shoots .75MOA with careful mechanics)

Not much room for improvement, you better keep what you have till you see if accuracy is better with bushings.

 

[Roamingdoc]

Really appreciate that picture. Was on Redding's site and the photos/diagrams of the dies were hard to view. Your photo is clear. Thanks.

Going to buy the Willis gauge and see if I can get the dies, the proper stand off and determine what difference it makes. I know that the stock gun shoots nicely and I am pleased with the performance. Just hoping to get a bit more out of it before the barrel goes and I have to invest.

Thanks