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Old September 11, 2013, 02:47 PM   #1
jwrowland77
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FL Size or Neck Size?

This may be opening Pandora's box, but when you reload your rifle ammo for a match, do you FL size every time, or neck size only, or mix it up?
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Old September 11, 2013, 06:46 PM   #2
Jim Watson
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Neck size for bolt, full length for auto.
There are reports that full length gives as as good or better accuracy than neck.
At the hunting or target level.
Bench rest neck only and not much of that.
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Old September 11, 2013, 08:09 PM   #3
iraiam
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Depends on several factors.

I have seen instances where neck sizing reduced the accuracy of the given load.

The best gains in accuracy I have seen with neck sizing were with belted magnum cartridges, 7mm mag, 300 win mag, 338 win mag. I no longer neck size for my .270 or 30-06 rifle.
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Old September 12, 2013, 04:35 PM   #4
243winxb
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FL Bushing Die

Full Length sizing.
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Old September 12, 2013, 06:57 PM   #5
Brian Pfleuger
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Both, or sometimes not both, it depends.


I use a Lee collet die to size the neck and then a Redding body die to size the body and "bump" the shoulder about 0.002.

Competitive shooters (top level) all full-length size their cases.

For convenience and because in a factory gun with a good but not exceptional shooter it really doesn't matter, I often neck size only.
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Old September 12, 2013, 06:58 PM   #6
Bart B.
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Folks winning matches and setting records in NRA high power rifle matches have been doing so with proper full length sizing dies for decades. The die's neck is about .002" smaller than a loaded rounds neck diameter; RCBS or Redding full bushing dies are the best commercial ones made these days that do that. And the fired case shoulder is set back no more than .002" New belted cases have produced as good of accuracy as proper full length sized ones that have the. Accuracy attained testing rifles and ammo has equalled what long range benchresters get these days.

Benchresters neck only sized for decades, but they've recently switched over to full length sizing for the most part. The dies they use reduce case diameters and set shoulders back only .001", but that's enough. Their smallest groups are still as tiny as ever. But their largest groups are now a whole lot smaller.

Sierra Bullets' been full length sizing all their bottleneck cases used to test their stuff for accuracy since the 1950's. I doubt anyone shoots their bullets as accurate as they do. Their best match bullets go into 1/4 MOA at their 200 yard test range. No case prep nor load work up is ever done; they use the same recipie for each new lot of components and test barrel.

What most folks don't realize is a full length sized bottleneck case headspacing on its shoulder centers up front in the chamber just as perfect as neck only sized ones when the round fires. And without the interference between case body and chamber walls and shoulder that so often happens. And fired case necks are more perfectly centered on full length sized bottleneck cases as the case body is held in perfect alignment with the case neck as the neck's sized down.
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Old September 12, 2013, 08:09 PM   #7
jwrowland77
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FL Size or Neck Size?

Awesome, thanks for all the replies everyone and the lessons.

I personally FL resize everything but with just getting into competitive shooting I was just wondering what the top shooters and loaders do.
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Old September 19, 2013, 02:01 PM   #8
cosnyka
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Resizing

As an engineer/scientist/physicist I'm contemplating the impact of neck-sizing only (NSO) vs FL sizing on the flight of the projectile. Without delving into calculations, intuitively, the two largest factors for accuracy would be the barrel vibration (whipping) and the terminal force imparted on the back of the bullet as it leaves the muzzle. Bullet rotation and geometry also have an effect, but I'm assuming that is a constant while addressing sizing method. It's impossible, but let's also assume a perfect muzzle crown and bullet base interaction which pushes on the bullet perfectly concentrically. As the bullet leaves the muzzle it has no history of how the case was resized except for how it affects the "tuning" to the barrel and subsequent vibration (and harmonics), which, on a microscopic level causes the barrel to 'point' in a different direction. This might be the key: the more constant pressures from the NSO cases required to expand less into their mated chambers. FL sized cases allow for more variability at the beginning of the pressure curve. Even if it's insignificant, I would still NSO to increase case life. A ridiculously thick barrel would solve all the problems of any influence on vibrations.
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Old September 20, 2013, 01:41 PM   #9
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cosnyka, you're right about the barrel whipping versus accuracy. It was proved a hundred years ago that bullets leaving as the muzzle axis whips up to its highest angle are compensated for the muzzle velocity they leave at. Slower ones leave later and at a higher departure angle; faster ones sooner at a lower departure angle. At the longer ranges, accuracy is better than at shorter ones. The Brit's SMLE .303's were/are famous with this with big muzzle velocity spreads using cordite. Even the military's M14 rifles demonstrated this as their gas port being mid point in the barrel bowed its muzzle angle downward a bit while the bullet moved forward in the front half of the bore. Front locking bolt action rifles typically don't exhibit this except at the very short ranges where it has a small beneficial effect.

The main reason full length sized cases tend to be more accurate than neck only sized ones is there's less interference between a case with moderate clearance between its body and the chamber than those with minimal clearance. As no chamber nor cartridge case is perfectly round, with minimal clearance there will be interference between case and chamber repositioning the round a tiny bit. That causes different waves of vibration with different amounts and directions in the barrel when the round fires. With enough clearance, that won't happen and the barrel whips the same for each shot fired.

This is the reason benchresters, for the most part, switched over to full length sizing their fired cases. But they don't reduce their fired case body diameters nor set shoulders back more than about .001"; enough to ensure clearance and no interference whatsoever for every round fired. This also ensures there will be no binding at all as the bolt's closed on a live round. Even the slightest binding of a microscopically too large of case degrades accuracy; the bolt must close to exactly the same place for every shot fired.
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Old September 20, 2013, 02:09 PM   #10
Wallyl
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I shoot cast bullets in my .223 Rem, .22-250 Rem, .243 Win, 7mm Rem Mag, .30-06, 8mm Rem Mag, .378 Wtby Mag, .444 Marlin, & a .45-70....and neck size them all. I do believe I get better accuracy doing so, but do admit that the difference is not is not dramatic.
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Old September 23, 2013, 03:40 AM   #11
JL Wesson
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I neck size only.

I have to say that I reload for a SMLE in 303British:
- these rifles have oversize chambers (for use in muddy trenches)
- .303Br head-spaces on the rim.

For the above mentioned reason NSO is preferable in my opinion and you get fire-formed brass for your reloads.

Do you gentlemen think I am on the right track?
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Old September 24, 2013, 01:55 PM   #12
jwrowland77
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Right now I FL size everything. One, because I really don't know the proper way of trying to just bump the shoulders back and neck size, but I always figured the FL sizing every time, helps to keep everything as consistent as possible.
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Old September 24, 2013, 02:04 PM   #13
Wallyl
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Thinking about this some more...I guess to really find out one has to shoot both and compare, using identical components. I would guess that for most that the difference would not be insignificant.
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Old September 24, 2013, 08:20 PM   #14
243winxb
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223 Rem.

The fired, neck sized case, has 4% more internal volume then a FL sized case that has been returned to factory new dimensions. Soon or later you will have to bump the shoulder back by FL sizing. This small volume change may make a different in accuracy, as energy is used to expand the brass on firing. A load worked up with a neck sized case may be different when FL sized. Doing your own testing is the only way to know.
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Old September 28, 2013, 07:10 AM   #15
Bart B.
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Depending on how much smaller a full length sized case is in volume than a neck only sized one, there can be as little as a 1% change in capacity. Few, if any, full length sizing dies return a case to its original, new and unfired dimensions. And in my experience, new cases give better accuracy than neck only sized ones.

I agree that doing your own testing is the only way to know.

But run the same test a few times. If the results are not within 10% of each other, it's not a good test. Good tests of rifle and ammo accuracy give close to (within 10%) the same results all the time.
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Last edited by Bart B.; September 28, 2013 at 08:55 AM.
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Old October 6, 2013, 04:12 PM   #16
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I'm little late on posting this but here something current on reloading for the F-Class open rifle

Shiraz: On the .300” WSM [I run] a tight-neck .336” chamber for turned necks. Basically, I fire-form all my brass in a fire-form barrel and save the good barrels for matches. Gordy is so good that he can chamber different barrels to within .0002” in the headspace dimension. That way I can have several same-caliber barrels and can use the same brass for all those barrels. I use a .0005″ shoulder bump for my brass. I load the bullets so that the bearing surface sits above the doughnut ring.

Here is the rifle and above comment

http://bulletin.accurateshooter.com/...sm-f-open-rig/
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Old November 21, 2013, 02:04 PM   #17
coalroller
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FL Size or Neck Size?

I full length size mine every time, when reloading for comp.
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Old November 21, 2013, 03:55 PM   #18
Wallyl
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I neck size all my six bottle neck calibers from .223 Rem to .378 Weatherby Magnum. However I only shoot cast bullets in them and all my rifles are bolt action. I do believe I get a bit more accuracy by doing so, but admit the difference is small. I don't believe neck sizing makes the brass last longer, as most brass get neck splits after X no. of firinigs. Lately I have started to neck size .444 Marlin & .45-70's that I shoot in Marlin lever action rifles...using .44 and .45 caliber pistol carbide dies...I only size the first 3/8" of the case neck with them
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Old November 21, 2013, 10:28 PM   #19
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You know, in a rifle match you are shooting against time and conditions. Time is nice and linear, but conditions are always now and later. You can't predict later but you better be shooting now when the conditions are right, because you may run out of time before they come back again.

So, if you neck size, expect to have to knock out a few cases with a cleaning rod and burn up time when you should be shooting now.

Neck sized cases sound like an excellent way to earn a crummy score.

But hey, that is why you drove three hours, spent $60.00 in gas, $25.00 in match fees, and shot ammunition that costs about $1.00 a round. To end up with a crummy score.

I am doing that with ammunition that functions perfectly, I am certain that my score would be even more crummy if I had to break position, get a cleaning rod, and knock out neck sized ammunition.

Could I consider that improvement?
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Old November 22, 2013, 10:03 AM   #20
coalroller
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FL Size or Neck Size?

Quote:
Originally Posted by Slamfire View Post
You know, in a rifle match you are shooting against time and conditions. Time is nice and linear, but conditions are always now and later. You can't predict later but you better be shooting now when the conditions are right, because you may run out of time before they come back again.

So, if you neck size, expect to have to knock out a few cases with a cleaning rod and burn up time when you should be shooting now.

Neck sized cases sound like an excellent way to earn a crummy score.

But hey, that is why you drove three hours, spent $60.00 in gas, $25.00 in match fees, and shot ammunition that costs about $1.00 a round. To end up with a crummy score.

I am doing that with ammunition that functions perfectly, I am certain that my score would be even more crummy if I had to break position, get a cleaning rod, and knock out neck sized ammunition.

Could I consider that improvement?
Thumbs up to this guy!
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Old November 22, 2013, 01:13 PM   #21
Brian Pfleuger
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While I have no doubt at all that competitive shooters long ago figured out that properly FL sized ammo is more accurate than neck sizing, a whole bunch of regular folks neck size ammunition and it's really not a functionality issue if done correctly, any more than FL sizing is.
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Old November 25, 2013, 01:02 AM   #22
Bart B.
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Newcomers to this thread, read posts 6 and 9.
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