I have a 24" 1x8 twist rifle that I have not got the accuracy that I expected yet. I have not tries all powders or loads, but I was reading where someone turned a mediocre shooter into a tackdriver by just neck sizing. Looking for more info on this subject. I am getting about 1" groups and a little better @100yds now.
Neck sizing for accuracy???
- Thread starter BUGUDY
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I agree with Walkalong 100%.
ranger335v
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Neck sizing, like trying different primers, uniforming flash holes, etc, is a small tweek. Such tweeks can/may gain us a little but it's VERY unlikely any of them standing alone will cut groups in half, or even close to half.
Consider the area covered by a full inch circle vs. a half-inch circle for a group. The smaller circle is half the diameter but only one quarter the actual area of the larger, meaning it's not twice as difficult to attain, it's four times more difficult!
Bullet choice is usually the most important single factor in the assembly of accurate ammo.
Consider the area covered by a full inch circle vs. a half-inch circle for a group. The smaller circle is half the diameter but only one quarter the actual area of the larger, meaning it's not twice as difficult to attain, it's four times more difficult!
Bullet choice is usually the most important single factor in the assembly of accurate ammo.
dagger dog
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Just a quip, I have shot my smallest group, with one rifle, while fire forming new brass so I could just neck size the next time. The fire formed brass shot as well but not better than the new brass.
I think bullet , powder selection and seating depth have a greater influence on accuracy for a specific rifle.
I think bullet , powder selection and seating depth have a greater influence on accuracy for a specific rifle.
something vague
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I agree with Dagger Dog and most everyone else. But I would also recomend that you do start neck sizing, not just for smaller groups but for longer brass life, ease of the loading process, and sometimes the larger case capacity will gain a slightly larger charge which could lead to better accuracy. The later being the less likely one of them all.
ranger335v
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Longer case life from neck sizing is a toss up, depending on you individual chamber and individual dies. If your brass is now failing due to body splits, yes. If it's from neck splits, no.
What greatly changes the expected case life from neck sizing is IF you anneal the necks after maybe each 5-6 loads. Otherwise, you won't see much, if any, difference in life.
The unique Lee Collet neck sizer works necks the absolute minimum so cases tend to last longer than they do with conventional neck sizers. And the Collet die usually makes straighter necks for more accurate ammo. But, it works differently so if a user won't take the time to understand and learn to use it correctly, he is better off to get a conventional neck die.
What greatly changes the expected case life from neck sizing is IF you anneal the necks after maybe each 5-6 loads. Otherwise, you won't see much, if any, difference in life.
The unique Lee Collet neck sizer works necks the absolute minimum so cases tend to last longer than they do with conventional neck sizers. And the Collet die usually makes straighter necks for more accurate ammo. But, it works differently so if a user won't take the time to understand and learn to use it correctly, he is better off to get a conventional neck die.
The Forster bushing style neck sizer and micrometer seater or the Redding set up are a couple of the best choices out there for loading for accuracy with threaded dies. It still won't be a miracle worker, but it won't be a die problem and you can look elswhere.
ranger335v
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Problem with bushing dies it they can only make the OUTSIDE of all the cases the same. Therefore, the user must turn all necks to the same thickness or the bullet tension (the "interference fit", actually) will vary from case to case. And some folks use too small a bushing so they get more neck run-out than the size die might otherwise give. I don't think that's good.
The Lee collet neck sizing die makes all necks the same proper INSIDE diameter, no matter the neck thickness variations.
The necks will be straight too. That's better, or at least easier. No seater can make concentric ammo if the necks aren't straight to start with.
The Lee collet neck sizing die makes all necks the same proper INSIDE diameter, no matter the neck thickness variations.
The necks will be straight too. That's better, or at least easier. No seater can make concentric ammo if the necks aren't straight to start with.
USSR
Member
Have found this to not be the case at all (no pun intended). Have been using bushings without neck turning and shooting 1,000 yard competition for many years without problems. If problems with bullet tension was going to show up, it would certainly appear as stringing at 1k.
Don
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It's been my experience that any die that sizes the neck will end up with the case having a mouth diameter that varies with neck wall thickness. Thicker neck walls for a given caliber will spring back a different amount than thinner ones. Doesn't matter whether one uses a neck only (bushing or mandrel) or neck/shoulder bushing as well as a lapped out full length sizing die that doesn't need an expander ball. If you want perfect uniformity in mouth diameter, you gotta turn all the neck walls to a uniform thickness. My experience shows that half a thousandth of an inch spread is fine.
Sierra Bullets has been full length sizing all their cases used to test bullets for accuracy. When one understands how both full length and neck only sized rimless bottleneck cases fit the chamber when the round's fired, one may understand why full length sizing has proved more accurate than any type of neck only sizing.
One will see the difference between neck and full length sizing much easier if they only use the largest group fired with a particular load as the measure of its accuracy. And one shoots at least 20 shots per group to test it. Basing accuracy on the smallest group is a waste of time; those tiny ones only happen a small percentage of the time.
Sierra Bullets has been full length sizing all their cases used to test bullets for accuracy. When one understands how both full length and neck only sized rimless bottleneck cases fit the chamber when the round's fired, one may understand why full length sizing has proved more accurate than any type of neck only sizing.
One will see the difference between neck and full length sizing much easier if they only use the largest group fired with a particular load as the measure of its accuracy. And one shoots at least 20 shots per group to test it. Basing accuracy on the smallest group is a waste of time; those tiny ones only happen a small percentage of the time.
something vague
Member
Here we go again...
Yep..........
.................
It is true that using bushings sizes the neck mostly to the same outside diameter. It is also true that the Lee Collet die sizes the brass mostly to the same inside diameter.
I also think it is true that in standard chambers it matters not one whit.
I do think it is beneficial to ream/turn case necks for tight necked match chambers when using bushing dies. We use a combination of things to line the bullet up straight using tight necked chambers and carefully prepped brass.
It either needs to be dead straight, or a sloppy fit like Bart is talking about with full length sizing.
A round tight in a chamber but off center would certainly shoot worse than a full length sized round loose in a chamber that can "center" its self when fired.
My 2 cents. Over and out..............Carry on..........
.................It is true that using bushings sizes the neck mostly to the same outside diameter. It is also true that the Lee Collet die sizes the brass mostly to the same inside diameter.
I also think it is true that in standard chambers it matters not one whit.
I do think it is beneficial to ream/turn case necks for tight necked match chambers when using bushing dies. We use a combination of things to line the bullet up straight using tight necked chambers and carefully prepped brass.
It either needs to be dead straight, or a sloppy fit like Bart is talking about with full length sizing.
A round tight in a chamber but off center would certainly shoot worse than a full length sized round loose in a chamber that can "center" its self when fired.
My 2 cents. Over and out..............Carry on..........
What caliber are you shooting? What type of accuracy do you expect to get? How good is the rest of the rifles components? action, bedding, stock, etc etc
For what it's worth, barrels with that fast twist are more finicky to get to shoot than something with say 1-14" twist...........all things being equal.
For what it's worth, barrels with that fast twist are more finicky to get to shoot than something with say 1-14" twist...........all things being equal.
Walkalong says:
I don't think very many folks know why and how.
All chambered rimless bottle neck rounds are loose to some degree in all chambers but the difference is only a thosandth or two. When fired, they all are centered perfectly where it counts regardless of how loose or tight they are.
I don't think very many folks know why and how.
USSR
Member
I believe Walkalong is talking about the difference between tight necked chambers as used in benchrest and standard chambers, and not the case body size difference between FL sized brass and those that are not. There is more than a thousand or two between them.
Don
Yep. And I stand by my statement.
Since getting the bullet started as perfectly aligned with the bore as possible is the goal, then it doesn't matter how we prep or how we size? Barts confusing me with his conflicting statements. I also fail to understand how carefully partially neck sized rounds have the same looseness in a chamber as full length sized rounds in a standard chamber like Bart says.....but what do I know, I only shoot 5 and 10 shot groups, not 30 shot groups.
30 shot groups in the real world will show shooter error more than a lack of pure accuracy potential.
I know, not hard to confuse me.
Centering the bullet/neck in the chamber's front end has nothing to do with the case neck or chamber neck diameter when a rimless bottle neck round's fired. There's at least a thousandths or two clearance with "tight" chamber necks and SAAMI chambers will have a lot more.
Such cases center their shoulder on the chamber shoulder when the case is driven hard against the chamber's shoulder by firing pin impact. And the case shoulder gets set back a few thousandths when this happens. Whatever the concentricity is between the case shoulder and case neck determines where the bullet's positioned when the round's fired. And both neck only and full length sized cases are off center in the chamber at their pressure ring (about 2/10ths inch in front of case head) a thousandth or two as they're pressed there by the extractor.
Full length sizing cases typically centers the case neck better in the case shoulder. But you'll have to measure neck runout at the case mouth with the case supported at the pressure ring and its datum point on the shoulder to see it. Neck only sizing doesn't support the case body to center the sized-down neck on the shoulder. As there's no such thing as perfectly round chambers and cases, it's best to have enough clearance around the case body to ensure minimum interference between the case body and chamber area around it.
So all the cases are crooked in the chamber a tiny bit when fired; front's centered at the shoulder and back end pressed off center by the extractor. Even with perfectly round and straight ammo (zero bullet runout), the bullet still enters the rifling a bit crooked.
Such cases center their shoulder on the chamber shoulder when the case is driven hard against the chamber's shoulder by firing pin impact. And the case shoulder gets set back a few thousandths when this happens. Whatever the concentricity is between the case shoulder and case neck determines where the bullet's positioned when the round's fired. And both neck only and full length sized cases are off center in the chamber at their pressure ring (about 2/10ths inch in front of case head) a thousandth or two as they're pressed there by the extractor.
Full length sizing cases typically centers the case neck better in the case shoulder. But you'll have to measure neck runout at the case mouth with the case supported at the pressure ring and its datum point on the shoulder to see it. Neck only sizing doesn't support the case body to center the sized-down neck on the shoulder. As there's no such thing as perfectly round chambers and cases, it's best to have enough clearance around the case body to ensure minimum interference between the case body and chamber area around it.
So all the cases are crooked in the chamber a tiny bit when fired; front's centered at the shoulder and back end pressed off center by the extractor. Even with perfectly round and straight ammo (zero bullet runout), the bullet still enters the rifling a bit crooked.
something vague
Member
But wouldn't a neck sized only case have it's shoulder tighter against the chamber as if it was a mold, therefore creating a better chance of the bullet being centered than if the shoulder had been set back again by the F/L die? I think that you're over analyzing what you think is taking place inside the chamber as the round is being fired. For years people have been neck sizing and claiming better results than if they F/L sized. Now I don't neccessarily buy into that claim but I sure as hell am not getting worse accuracy from neck sizing only. And once I factor in the abuse the brass takes and the simplicity of the reloading process, I see absolutely no reason why F/L sizing would be more advantageous than neck sizing only. And believe it or not, I get much less neck runout with the Lee Collet die than I do my Comp. F/L sizing die. So for me, the proof is in the pudding. I can't actually tell you exactly why neck sizing works better for me and don't believe anyone really knows what's taking place inside the chamber once the firing pin lands on the primer. All you can do is speculate, which ultimately turns into some over analyzing what they think happens. All we can do is experiment and do what works best with your individual rifle. Hope I made some sense.
Walkalong says:
High power rifle competitors often shoot 25 to 30 consecutive shots in 20 to 25 minutes slung up in prone in long range matches. And folks on international teams shooting the prone match (either smallbore rimfire or high power centerfire) shoot 60 record shots in 75 minutes. Their last 5 shots are fired with the same aiming and let off precision as the first 5 are. Many of these folks test rifles and ammo shooting this way but put a sand bag under their front hand holding the fore arm and another under the stock’s toe; this lets them hold 1/10th MOA (or better) on the target instead of 3/4ths MOA without the bags. In the “real world” when absolute accuracy without human intervention is needed, they’ll clamp their rifles in a machine rest that equals the rail guns (unlimited class) benchresters, Sierra Bullets and military arsenals use. One can shoot as many consecutive shots as the rest doesn’t get tired. Here’s a link to a web site showing the machine rest David Tubb (and others) uses testing his Model 2000 rifles using his own properly full length sized cases: http://www.flickr.com/photos/12787226@N00/sets/72157594303093714/detail/
Something Vague has several comments:
It’s not good for accuracy if the bolt binds somewhat when closed on a tight-fitting case (one whose headspace is greater than chamber headspace resulting in a “crush” fit). When this happens, the locking lugs won’t seat at the same place for each shot and that causes irregular barrel whipping while the bullet’s going down the bore and it won’t leave at the same place for each shot.
* Virtually all high power rifle National Champions. Many of their test groups are smaller than benchrest records. But the groups they shoot in competition are much bigger as they're not shot from a rest.
* Many benchresters have switched to full length sizing.
* Sierra Bullets; been doing it since the early 1950's. Their best match bullets shoot 1/4 MOA or better from full length sized cases at 200 yards. And some have tested around 1/8th MOA for several consecutive 10-shot groups; evidence the bullet jackets were extremely uniform in thickness and the bullets were perfectly balanced.
* New cases, such as those used in 7.62 NATO match ammo made at Lake City Arsenal shoot MOA at 600 yards in semiauto service rifles. Commercial .308 Win. Match ammo (again, new cases) shoot 2/3rds MOA at 600 in the same rifles. Both ammo types will shoot 1/3 MOA or better at 100 yards in the same rifles.
When you open the bolt holding a fired case, its extractor pushes the case head/rim to the side holding it in place until it’s ejected. That same extractor pushes the case head to the top where it stops against the chamber wall when the bolt’s closed on it.
Measure the case headspace on an empty primed rimless bottleneck case. Chamber that empty primed case, fire it, then remove the case and measure case headspace again. It’s now shorter; the shoulder was set back. You can also make a series of handloads with each one having 1 grain less powder in it; do not load less than 15% below maximum. Starting with the max load, fire each one and note how far the primer’s pushed out of the case. When you start seeing primers pushed out, this means the case shoulder was set back but there wasn’t enough peak pressure to push/stretch the case body back to where the case head stops against the bolt face but there’s enough pressure to push the primer out a bit.
The above aside, if one trying full length sizing and sets the fired rimless bottleneck case shoulder back more than a couple thousandths and uses an expander ball instead of a die not needing one, then they may well get better accuracy by sizing just the neck. Nobody I know who equals or betters benchrest, neck only, accuracy by full length sizing this way understands why full length sized cases with whose shoulder’s are set back too far don’t shoot very accurate. This the thing I don’t understand. I asked Sierra Bullets former Head Ballistician about this years ago; he didn’t have an answer but said he’ll keep on full length sizing cases to test their bullets in.
That depends on how one shoots them. If you’re shooting the way most folks test ammo, rifle held against the shoulder and its fore end resting atop some rest on a bench top and there’s a lot of recoil, then 30 consecutive shots will start making you shoot less accurate after 15, sometimes only 10 shots. And it’s harder with heavier (1 pound or more) trigger pull weights than lighter ones (less than a pound). Anytime most folks shoot a rifle atop a bench in any way other than free recoil (rifle’s untouched by humans except for pinching off it’s few-ounce trigger), the accuracy they get will be all over the place. That’s ‘cause the rifle moves off the desired aiming point while the bullet’s going down the barrel.
High power rifle competitors often shoot 25 to 30 consecutive shots in 20 to 25 minutes slung up in prone in long range matches. And folks on international teams shooting the prone match (either smallbore rimfire or high power centerfire) shoot 60 record shots in 75 minutes. Their last 5 shots are fired with the same aiming and let off precision as the first 5 are. Many of these folks test rifles and ammo shooting this way but put a sand bag under their front hand holding the fore arm and another under the stock’s toe; this lets them hold 1/10th MOA (or better) on the target instead of 3/4ths MOA without the bags. In the “real world” when absolute accuracy without human intervention is needed, they’ll clamp their rifles in a machine rest that equals the rail guns (unlimited class) benchresters, Sierra Bullets and military arsenals use. One can shoot as many consecutive shots as the rest doesn’t get tired. Here’s a link to a web site showing the machine rest David Tubb (and others) uses testing his Model 2000 rifles using his own properly full length sized cases: http://www.flickr.com/photos/12787226@N00/sets/72157594303093714/detail/
Something Vague has several comments:
I don’t think so; but I do think I’m “under” analyzing ‘cause there’s one thing I don’t quite understand. Read on.
Fired case dimensions are not the same as chamber dimensions. Cases from bolt action rifles spring back a bit from the chamber walls as pressure drops; if they didn’t, they would be hard to fully chamber (unless oriented the same as when fired) due to both case and chamber not being perfectly round. Measure a fired case and the chamber it came out of and you’ll see how much smaller the case dimensions are compared to the chamber’s. And in rifles with a spring-loaded plunger type ejector and the bolt closed, the plunger pushes the loaded round forward in the chamber until the case shoulder stops against the chamber shoulder.
It’s not good for accuracy if the bolt binds somewhat when closed on a tight-fitting case (one whose headspace is greater than chamber headspace resulting in a “crush” fit). When this happens, the locking lugs won’t seat at the same place for each shot and that causes irregular barrel whipping while the bullet’s going down the bore and it won’t leave at the same place for each shot.
And others claim proper full length sizing is the most accurate. Here's a few:
* Virtually all high power rifle National Champions. Many of their test groups are smaller than benchrest records. But the groups they shoot in competition are much bigger as they're not shot from a rest.
* Many benchresters have switched to full length sizing.
* Sierra Bullets; been doing it since the early 1950's. Their best match bullets shoot 1/4 MOA or better from full length sized cases at 200 yards. And some have tested around 1/8th MOA for several consecutive 10-shot groups; evidence the bullet jackets were extremely uniform in thickness and the bullets were perfectly balanced.
* New cases, such as those used in 7.62 NATO match ammo made at Lake City Arsenal shoot MOA at 600 yards in semiauto service rifles. Commercial .308 Win. Match ammo (again, new cases) shoot 2/3rds MOA at 600 in the same rifles. Both ammo types will shoot 1/3 MOA or better at 100 yards in the same rifles.
It’s easy to find out what happens to the loaded round when its chambered and fired. Some people can do more than speculate. Much can be observed by simple tests and measurements. A lot of people have done what’s explained below and learn what happens.
When you open the bolt holding a fired case, its extractor pushes the case head/rim to the side holding it in place until it’s ejected. That same extractor pushes the case head to the top where it stops against the chamber wall when the bolt’s closed on it.
Measure the case headspace on an empty primed rimless bottleneck case. Chamber that empty primed case, fire it, then remove the case and measure case headspace again. It’s now shorter; the shoulder was set back. You can also make a series of handloads with each one having 1 grain less powder in it; do not load less than 15% below maximum. Starting with the max load, fire each one and note how far the primer’s pushed out of the case. When you start seeing primers pushed out, this means the case shoulder was set back but there wasn’t enough peak pressure to push/stretch the case body back to where the case head stops against the bolt face but there’s enough pressure to push the primer out a bit.
The above aside, if one trying full length sizing and sets the fired rimless bottleneck case shoulder back more than a couple thousandths and uses an expander ball instead of a die not needing one, then they may well get better accuracy by sizing just the neck. Nobody I know who equals or betters benchrest, neck only, accuracy by full length sizing this way understands why full length sized cases with whose shoulder’s are set back too far don’t shoot very accurate. This the thing I don’t understand. I asked Sierra Bullets former Head Ballistician about this years ago; he didn’t have an answer but said he’ll keep on full length sizing cases to test their bullets in.
I tried neck-sizing for accuracy. It seemed to improve the groups for a couple of rifles but made no difference in others.
Tried a test with a Redding FLR bushing die with the expander removed and just setting the shoulder back ~.002. Both sample sets (the ones that improved with NS and the ones that didn't) showed improvement over traditional FLR.
I think that I will stick with FLR with a.002 shoulder bump. It just provides more consistency. When NSing only, every few reloads you have to set the shoulder back. That changes the volume of the case and your accuracy might suffer.
Also have been having good luck using Redding body dies to bump the shoulder back along with a Lee Collet to fix the necks. This works very well and the brass life is fantastic.
Someone makes a shoulder-bump die that sounds interesting but I already have way too much money sunk in dies.
Tried a test with a Redding FLR bushing die with the expander removed and just setting the shoulder back ~.002. Both sample sets (the ones that improved with NS and the ones that didn't) showed improvement over traditional FLR.
I think that I will stick with FLR with a.002 shoulder bump. It just provides more consistency. When NSing only, every few reloads you have to set the shoulder back. That changes the volume of the case and your accuracy might suffer.
Also have been having good luck using Redding body dies to bump the shoulder back along with a Lee Collet to fix the necks. This works very well and the brass life is fantastic.
Someone makes a shoulder-bump die that sounds interesting but I already have way too much money sunk in dies
.Kelbro mentions:
But the difference in case capacity doesn't matter. It's the case capacity at peak pressure when the case is expanded all the way out against the chamber wall that matters.
Kelbro, that's what happens with neck only sizing without setting the shoulder back. When the case headspace grows enough and the bolt face ain't squared, the high spot on the case head gets in contact with the high spot on the bolt face; result is the bolt binds which is a known cause of poor accuracy.
But the difference in case capacity doesn't matter. It's the case capacity at peak pressure when the case is expanded all the way out against the chamber wall that matters.
I find this statement from Redding to be interesting ...
"Redding has now introduced neck sizing dies that use interchangeable sizing bushings in .001" increments. These dies can help reduce overworking of the brass and the resulting loss of concentricity."
Also ...
"We have conducted many tests over the years on the various factors contributing to concentricity problems with bottleneck cases. We have repeatedly found a definite correlation between the uniformity of the brass (or lack of it) and the resulting concentricity of the neck to the body of the case.
An interesting experiment also revealed that neck turning of brass that was intentionally sorted as non-uniform, showed little or no concentricity improvement when used in standard S.A.A.M.I. spec chambers. Conversely brass that was sorted and selected for uniformity remained uniform and concentric with or without a neck turning operation."
Bart, I've read (and enjoyed) your "full-length rather than neck-size" posts time and time again. You always talk about Sierra and what they do, but frankly, I could care less what Sierra does or did 20 years ago. They make very good bullets ... that's it. They're not in the reloading business per se so I look to Redding for guidance. I suppose it's possible that Redding and other die manufacturers have managed to pull off the greatest reloading hoax in modern history with their line of neck-sizing dies, but I doubt it. I have NEVER had a rifle that was more accurate with FL sizing compared to neck-sizing, but then again, I've used Redding dies for all.
Your full-length sizing philosophy is based on the single premise that neck-sized cases don't have necks concentric to the body of the case when compared to full-length sized cases. My response to this is .... ... based on my experience and measurements of .308 Win, .300 Win Mag, .223 Rem and .300 WSM cases all resized with Redding neck-sizing dies only. As I mentioned before, measurements have indicated bullet runout of +/- 0.0005" with cases that have been neck-sized only.
I posted a target that I shot last week with 20 rounds shot in 20 minutes at 600 yards in less than ideal conditions by a less than qualified shooter. The deviation of those 20 shots in the vertical direction was 4-1/2" (0.75 MOA) and 18 of them were within 3-1/2" (0.56 MOA). I BET that someone like you or Don could cut that in half using my rifle and my reloads. Those loads consisted of neck-sized Lapua brass and Nosler bullets.
Redding provides some useful information about neck-sizing here.
http://www.redding-reloading.com/techlinepages/concentricity_bushdies.htm
"Redding has now introduced neck sizing dies that use interchangeable sizing bushings in .001" increments. These dies can help reduce overworking of the brass and the resulting loss of concentricity."
Also ...
"We have conducted many tests over the years on the various factors contributing to concentricity problems with bottleneck cases. We have repeatedly found a definite correlation between the uniformity of the brass (or lack of it) and the resulting concentricity of the neck to the body of the case.
An interesting experiment also revealed that neck turning of brass that was intentionally sorted as non-uniform, showed little or no concentricity improvement when used in standard S.A.A.M.I. spec chambers. Conversely brass that was sorted and selected for uniformity remained uniform and concentric with or without a neck turning operation."
Bart, I've read (and enjoyed) your "full-length rather than neck-size" posts time and time again. You always talk about Sierra and what they do, but frankly, I could care less what Sierra does or did 20 years ago. They make very good bullets ... that's it. They're not in the reloading business per se so I look to Redding for guidance. I suppose it's possible that Redding and other die manufacturers have managed to pull off the greatest reloading hoax in modern history with their line of neck-sizing dies, but I doubt it. I have NEVER had a rifle that was more accurate with FL sizing compared to neck-sizing, but then again, I've used Redding dies for all.
Your full-length sizing philosophy is based on the single premise that neck-sized cases don't have necks concentric to the body of the case when compared to full-length sized cases. My response to this is ....
... based on my experience and measurements of .308 Win, .300 Win Mag, .223 Rem and .300 WSM cases all resized with Redding neck-sizing dies only. As I mentioned before, measurements have indicated bullet runout of +/- 0.0005" with cases that have been neck-sized only. I posted a target that I shot last week with 20 rounds shot in 20 minutes at 600 yards in less than ideal conditions by a less than qualified shooter. The deviation of those 20 shots in the vertical direction was 4-1/2" (0.75 MOA) and 18 of them were within 3-1/2" (0.56 MOA). I BET that someone like you or Don could cut that in half using my rifle and my reloads. Those loads consisted of neck-sized Lapua brass and Nosler bullets.
Redding provides some useful information about neck-sizing here.
http://www.redding-reloading.com/techlinepages/concentricity_bushdies.htm
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Bart B. said:
I've shot the same W-W Super .300 Win Mag cases four times in my "match" rifle now, neck-sized only. The bolt is as easy to open/close as it was for the first firing. I've been keeping an eye on the headspace measurements and the cases simply aren't growing at all, and why would they? The case is always going to spring back a few thousandths from the maximum chamber dimensions so if you have a precisely cut chamber, a trued bolt face and you neck size only, you shouldn't have to bump the shoulder back at all. So far I haven't had to bump the shoulders back on .300 Win Mag or .308 Win cases but I have Krieger barrels/chambers and Krieger "trued" both actions.
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