The Accurate Reloading Forums THE ACCURATE RELOADING.COM FORUMS Guns, Politics, Gunsmithing & Reloading Reloading Full Length Sizing v Neck Sizing In The 308 WinchesterGo | New | Find | Notify | Tools | Reply | |
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| Administrator |
SAKO TRG 22 160 grain Walterhog bullets, 40 grains Reloader 15, Federal 210M in RWS brass. 5 shot groups at 100 yards. Full length sized brass 1. 0.255 2. 0.622 3. 0.220 4. 0.260 5. 0.519 6. 0.690 7. 0.405 8. 0.348 9. 0.455 10. 0.571 Average = 0.4345 Neck sized brass 1. 0.477 2. 0.269 3. 0.536 4. 0.431 5. 0.522 6. 0.453 7. 0.211 8. 0.695 9. 0.321 10. 0.587 Average = 0.4502 We also tried Tungsten spray on the bullets, and here is the results. 1. 0.367 2. 0.412 3. 0.271 4. 0.499 5. 0.415 6. 0.626 7. 0.522 8. 0.283 9. 0.400 10. 0.486 Average = 0.4311 I will leave you form your own conclusions. | ||
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| One of Us |
Someone is going to have to decide if there is a difference in accuracy when comparing full length sized cases to neck sized cases. I have one chamber that is .002" longer than a field reject length chamber. I form cases for that chamber using 280 Remington cases. If I neck sized the fired cases I would have to wonder if time was a factor; firing the full length sized case will require more time for the case to expand from the shoulder to the case head. If I necked sized the fired cases the case does not require expanding before the pressure gets serious. F. Guffey | |||
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My conclusion is the difference in accuracy would be important to a target shooter. Dave | |||
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Personally I full length size and also apply a crimp. I reload for hunting and I want reliability, good feeding and bullets to stay in their cases despite being bounced about in vehicles, pockets, magazines etc. If it means I don’t get tiny little groups so be it. Do they shoot minute of deer to 200m thats fine by me. | |||
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For pure accuracy, partial full length resizing is the way to go, minimal shoulder bump.....somewhere around 2 ten thousandths. For my hunting rounds I full length resize, I only crimp over .375....... . | |||
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I also partially size the cases for 6mm-284 and 7mm Remington. Wind is enough of a variable without wondering about group sizes. The 7mm went from 1.5" three-shot groups to a little over 0.5" by tailoring the reloads to its peculiarities. Now the change to copper is pending, I'll be doing the tweaking all over again. TomP Our country, right or wrong. When right, to be kept right, when wrong to be put right. Carl Schurz (1829 - 1906) | |||
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Saeed you probably need to consider other variables to get an accurate comparison. * Same brass used? * Trimming? * Load variations? * Machine rest or human? * Cleaning between strings * Barrel heat during and between strings * Indoor/outdoor, wind? * Temperature Have you done a statistical analysis to determine if there is a significant difference between results? | |||
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Good question. I used an on-line (unpaired, 2-tailed t-test) and got P = 0.8254. Conventionally, P = 0.05 is considered significant (that the odds are 5 in 100 that the differences arose by chance). If P = 0.01, the odds are 1 in 100 that the differences arose by chance and if P = 0.001, the odds are 1 in 1000 that the differences are due to chance. So when P = 0.8, there's a strong suggestion that there is NO statistical difference between the two. | |||
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The name of the game is to get the bullet/cartridge center to be as close as possible in alignment with the bore's centerline. In Saeed's test if neck sizing only didn't beat full length size leads me to believe either his case necks vary in thickness around their circumference or the chamber isn't in perfect alignment with the bore centerline. Also the neck sizing die may have sized the necks crooked. | |||
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Exactly. There is another variable(s) that has not been accounted for.
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Gentlemen, All the tests I run are as one would encounter himself. All brass was the same - it was full length sized, shot, cleaned in a tumbler, checked for length again, neck sized and shot. Same rifle, same rest, same shooter. Same powder can, same box of primers. Brass originally was RWS Match Ammo. Fired several times. All are trimmed to length after each firing, if they require it. Full length die set was from RCBS. Neck die set from Redding. Same seating die was used for both - it is an RCBS die. Frankly, from reading some articles on the Net, I expected more variation. I think those of us with a bit of reloading experience would make their own decision, based on their own experience, and their own rifles. Sadly, that is not true of everyone who shoots. Not long ago I had a gentleman come here with 3 rifles chambered for the 308 Winchester. All different makes. He had almost 200 round of ammo, which he bought from a reliable source he had who reloaded ammo for him. He has been doing it for years, and happy with it, until now. All the ammo is loaded in S&B brass, which is not bad at all. He had problems chambering some of this ammo in his rifles. Some ammo would chamber in one rifle, but not the other two. Some ammo would chamber in two rifles, but not the third. A few would not chamber in any of them. I called the man who loaded the ammo, and found that he had collected once fired brass, and only neck sized them. I took a few of the worst ones, pulled the bullets out, and full length sized them, and loaded them again. All chambered perfectly in all the three rifles! The poor man had to spend some time pulling all the bullets out, and full length size all the cases, and loaded them again. Everything worked perfectly then. Biggest problem I see is the variations in factory rifles. And here is where an experienced shooter can tune his loads for best results. I have a 6PPC match rifle with a tight neck. Once the brass has been prepared for it, I only neck size it, and those cases seem to last forever. I have 2 375/404 rifles cut with the same reamer. The die was custom made for them, and I full length size my brass for both, used for hunting. The cases last for at least 15 firings. I say at least because that is when I notice some cracks developing on the should or neck. Funny enough, I have loaded those damaged cases, and they shot just as well as any of the others. As mentioned above, consistency if what we are after. How we achieve that is up to us. | |||
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"Same shooter"! Total bullshit then. You can't compare separate shooting sessions by the same shooter with different loads. Human variable discounts everything. The only way to do it is with machine rests and randomly selected components. Example: If you are looking at shooting 15 rounds of neck sized rounds then you must have at least 150 rds of neck sized ammo to choose 15 rds from in a random manner. | |||
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With respect . . . if one had loaded 1500 rounds of each neck and FL sized, and randomly selected 150 of each for testing, it would be wonderful. But where do we stop? Personally, I feel pretty secure with the n of this study: the sample size (n = 10 per set) is, IMO, appropriate, given the test used n-1 (which biases towards statistical difference, the bias decreasing as the number "n" tested increases). If the statistics had shown a statistically significant difference (P = 0.05 or less), you would have a point wrt human variability being a factor. Or other factors like barrel heat or cleanliness or wind of temperature . . . But the test did not show a difference: the two sets are, statistically speaking, the same. Therefore, given these parameters of this test, human variability and several other potential sources of error can be ruled out as causing a statistically-significant difference . . . because there is no statistically-significant difference. | |||
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I am unaware of anyone taking a machine rest on a hunt. | |||
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I will ask no one to forgive me for living in a different world; I accept it an I am happy with the arrangement. I have been loading 12 different loads of 10 rounds each in an effort to determine what the rifle likes. I built the rifle and performed the same test before the new owner took possession. Out of the 120 rounds I had no flyers and none of the groups opened up. So I ask the new owner what does the rifle like? I made it easy on myself because I used 12 different head stamps. The new owner claims the rifle likes everything. He said he zeroed the rifle with one round and he trained his two sons to do the same. And now the grandsons have started purchasing their own rifles because I have fallen behind. F. Guffey | |||
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And you mentioned that you were on a hunt where in this thread? | |||
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I came to the same conclusion a few years back. I used to use Redding Competition neck bushing sizers/seaters, first with the floating sizing carbide buttons and then no buttons, until I had someone re-work up a load for me and produced the same accuracy with plain Jane RCBS FL sizing & seater dies. Now all I use are Whidden Custom non bushing FL dies. IIRC they also found the non bushing FL dies had less runout than the bushing FL dies. Anyway, thanks Saeed for your work. There are two types of people in the world: those that get things done and those who make excuses. There are no others. | |||
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Case life?
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What about case life? How does case life factor into a comparison of two data sets that show no statistical difference? Case life is certainly a variable worth testing, and if you would like to do so, I'd be very interested in your results. I don't mean to be perverse, but I honestly don't understand where you're going. I start with this: there is NO statistical difference between the two sets of data Saeed posted. So examining the effects of any variables NOT included in his (well designed) study might be interesting in and of itself, but it has nothing whatsoever (zilch, nada) to do with what Saeed posted. If I don't understand what you are saying, please take a minute and put me straight. I am fallible and wide open to being dumb, wrong, careless or just a fool. Perhaps you should start another thread. I, for one, would be very interested in how you set your study up and what your results are. I am serious. I am not trolling you. | |||
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Perhaps my reading comprehension is off, or I just wanted to read into it what I wanted, but the general consensus on paper (or on the internet) seems to be that neck sizing is by far the "only" way to get really accurate ammo. Saeeds data shows it's just a wive's tale. And I've seen it first hand, not theoretically. Nothing more, nothing less. It's all about doing the same thing over and over again. As far as case life- I don't give a shit. I don't enjoy shooting at paper and going to the range is a chore. Now I shoot my bow nearly every day, because of the benefits of practice are real. But I don't need to shoot my rifles once they're sorted. Some rifles I haven't loaded for in years as I only bust 3 caps a year per gun: 1. to remember where I left my zero 2. at the lodge to ensure my rifle kept its zero and 3. pop a cap to drop an animal.....eg I bought two 100 ct boxes of Lapua .300 Win brass back in '04. I've only used less than 50 total and I've travelled the world with that rifle. There are two types of people in the world: those that get things done and those who make excuses. There are no others. | |||
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Exactly. Case life is not part of this test. Only accuracy. Case life is a function of the rifle in use, and the dies used to load for it. Again, experienced loaders would recognize this, and make any adjustments they deem necessary. | |||
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Come on Saeed. Anyone that is a KNOWLEDGEABLE reloader knows that full length or partial sizing makes the whole case smaller then the chamber, so the whole case expands EXCEPT the solid head. If that does you're exceeding maximum. With neck size, for all practical matters, only the neck expands. About the only thing on a neck sized case that is going to give up the ghost is the neck and you'll get neck splits for example. Now there are target shooters that have their chambers set up to where you don't have to size the case at all, not even the neck. Many tales of some shooters that have fired the same case over and over an astronomical amount of times. In most regular rifles eventually with neck sizing you have to full length size occasionally because the bolt will become a little snug closing on a cartridge. | |||
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Be that as it may . . . and with respect I ask: what does case life have to do with Saeed's data sets? They are what they are. Period. You cannot escape the fact that THERE WAS NO STATISTICAL DIFFERENCE between the two data sets he posted. All the criticism related to "variables not considered" would be perfectly appropriate had there been a statistical difference between the two samples. But there was no statistical difference, and I'd argue the statistics supporting the conclusion of "no difference" are very, very robust. If you want to set up another study, I encourage you to do so. But as to the issue of whether or not, in Saeed's 2 data sets, the sets are different . . . that question is settled. Again . . . if anyone wants to run a different study in which case life is different between 10 cases FL sized and 10 cases neck size . . . have at it! But it will have no bearing whatsoever on the validity of Saeed's study. | |||
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Case life I lose far more cases then i ever wear out. With common cases I never worry about case life just buy or find more. | |||
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Five shot groups are not sufficient to prove something to the third digit. There is an excellent article at the end of the Oct 2014 Shooting Sports USA on group size and accuracy: http://www.nxtbook.com/nxtbooks/nra/ssusa_201410/ This foundational article was written by small bore prone competitors who wanted to shoot perfect scores. In small bore prone a Match is a 40 shot event of two twenty shot targets. The typical 1600 round Smallbore bore prone tournament is 160 rounds fired for record, divided up into four 40 round Matches. Therefore the referenced article assumes that a 40 round group is the baseline. As anyone can see in table six, at least at 100 yards, a five shot group is 59% of the size of a 40 shot group, a 10 shot 74%, and a twenty shot 88%. A three shot group is below contempt, but three shot groups are the current standard for the shooting community because the leaders of the shooting community, that is in print Gunwriters, have convinced the shooting community that three shot groups are an exact measure of accuracy and consistency. Since smallbore prone shooters don't roll their own, the topic of who makes the best ammunition, and the grade, is always of interest. I can say, even having your rifle lot tested (40 shot groups) you really don't have confidence in your ammunition till you have fired a brick, which is 500 rounds. I don't know any good competitive shooters, be they across the course, or F class shooters that only neck size. Neck sized cases will at some point in the future, stick in the chamber, and that means taking time out to find a cleaning rod and knocking the case out of the chamber. Which by the time the case is out, the wind has changed. Shooters do play with special dies and size the case necks to certain exact dimensions, how much is dependent on their groups size experiment. | |||
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Saeed fired 10 shot groups. Could you be a little more explicit>I don't understand. Saeed fired 10 shot groups, not 5 shot groups. Could you please un-confuse me? Thanks. | |||
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Not true at all. At least in my own experience. If a round chambers, it will come out, unless it is over loaded. We have many match rifles, and all we do is neck size for them. Never came across the problem you mention. | |||
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The cartridge should fit the chamber like a rat turd in a violin case.   https://www.youtube.com/watch?v=lLG2kSrD40g | |||
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When it comes to silly quotes that one has to be the silliest. If a reloader does not know how to size a case to fit a chamber he should say "I do not know how to size a case to fit a chamber". And then there is Bart B's quote; reloaders should 'do like' the bench resters; bench resters full length sized their cases evetime. Nothing dummier than full length sizing when the reloaders does not know the length of the chamber from the shoulder of the chamber to the bolt face. F. Guffey | |||
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That's got to be one big rat. Dave | |||
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Always thought neck resizing made for more accurate ammo. Guess not! But maybe different in different rifles, just wondering! | |||
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I've only had to full length size one cartridge in 50 plus years of reloading. It was a 450 bpe made in the 1800s. Even then some of the cases wouldn't chamber. Normally I don't run the cases all the way into the sizing die, both bottleneck and straight. Dave | |||
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Maybe I got it wrong, this is what I read:
Did I misquote Saeed? | |||
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No, but I think maybe I was unclear. He shot ten 5-shot groups for NS and ten 5-shot groups for FL, and presented 10 averages for both NS and 10 for FL. So I ran the test on 10 averages in each of 2 groups. Each group had 50 measurements. (I excluded the tungsten group.) Sorry for lack of clarity (that's on me, entirely), and if I've confused you further, I'll be happy to try again. | |||
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Taking an average based on five shot groups, how close is that average to the true average of the population? I remember questions similar to that in statistics class. Instead of five shot averages, let us look at the extremes. The extreme diameter for the full length sized brass is 0.690" the extreme diameter for the neck sized brass is 0.695" the extreme diameter for the tungsten spray is 0.626" these measurements are all but identical to the tenth of an inch, for two of them to the hundredth of an inch. I am not going to believe that making inferences based on thousand's of an inch (measuring holes punched in paper) is believable. What you are seeing is the randomness in group size, and there is not enough information to claim there is any real difference between the reloading techniques. | |||
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Yup! Exactly so. | |||
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I agree. I've also have been reloading for 50 years. Started out with LEE handloaders that neck sized only. I also have several calibers I FLR for and several where I use LEE Collet Dies for neck only. There is no doubt that FLR shortens case life. Several rifles of mine exhibited case head separations when FLR'd. If you are shooting target grade barrels with minimum chambers then FLR vs neck may not be a big deal. But most folks are shooting production guns and military surplus barrels. Many of these chambers can be quite generous, especially military surplus. A proper fitting case is required. I've never had a neck sized case fail to chamber or even be hard to chamber. Just don't see it.
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There is no doubt that FLR shortens case life. Several rifles of mine exhibited case head separations when FLR'd. Bobster, have you ever tried to apply K Thompson’s philosophy of the rat turn in the violin case to your experiences? I am thinking if anyone understood what was said they would disagree then again I could be giving a few more credit than they deserve. F. Guffey | |||
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| Administrator |
This might be due to the rifle chamber. If the rifle has a relatively large chamber, sizing the case down and firing it again will cause cases not to last as long. We use minimum dimension reamers, and have no problems as such. Belted cases are the worst, followed by some 308 Winchester’s. | |||
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Saeed, thank you, you are correct, I was wondering why/how the turd in the violin case got an exemption on case head separation. I do not believe "a way with words" can be an excuse for not knowing about case length and chamber length. F. Guffey | |||
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The Accurate Reloading Forums THE ACCURATE RELOADING.COM FORUMS Guns, Politics, Gunsmithing & Reloading Reloading Full Length Sizing v Neck Sizing In The 308 Winchester
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