Full Length or Neck Only; What's Best Resizing for Accuracy?

[tim_w]

When you are looking strIctly at effects on accuracy, more precisely consistency in POI reducing/eliminating as many variables as possible is necessary. Thus LR is not the place too look unless all the work was in indoors where enviornmentals are controlled. Given how accurately target groups can be measured even short range groups can give serious insight.

The issue here is that shooters here are mainly hunters and LR hunters at that. We are not usually going to accept things a 100/200 BR shooter is.

Does anyone by chance recall a gentleman by the name of Virgil King? Maybe read about him? For those that gave not he happened to be a very meticulous BR shooter t8hat owned a large warehouse outside Houston. He was actually a construction contractor by trade his whole life. Friends with Bob Fischer, Ed Shilen, TJ Jackson many to BR shooters of the time 70s and 80s.....

I am sure Bart recalls as I have seen and participated in threads back in the old Bulletin Board and emailing chain list days of the public internet infancy yrs. You, Toby Bradshaw, Doug White, Gale McMillan, Ed Harris etc would all kick things back and forth in the email lists back around 1990. +/-.

I recall the numerous mail chains on FL vs Neck vs bump effects actions tolerance mechinics extractor ejector types etc. I was just getting serious into precision shooting and extended range shooting (past typically accepted hunting distances) I saved many of those threads and built many handloads procedures based on those for hunting and service rifles comp.


As far as I know, in terms of rifle accuracy/consistency testing (from a short range BR perspective), at least publicly released, no one has never exceeded what Virgil and that group of elite BR shooters did over a period of 8 yrs on that indoor controlled enviornment 100-325 yd max range setup down the center on his warehouse. BTW Virgil passed away in '04.

I recommend those not familiar with the '93 Precision Shooting Magazine's Special Issue #1 1993 take the time to read it. I think, I still have all my issues of PS. It may not apply 1/1 to our shooting there are still effect /results & wisdom IMO to glean.

Here is a link to PDF of that article:

Secrets of the Houston Warehouse by David Scott

To be clear, I am not saying any of these are things that are advisable for LR hunting etc.

Still, consider Virgil said that they did not consider a setup was shooting well until it consistently shoot its back to back 5rd groups inside 0.080" @100yd.

We now know, as we have tools to measure today, some of their conclusions as to "why" certain specs or procedures effected consistency were possibly incorrect but the effect it had was still clear. Example we have gauges on arbor or die presses to read bullet seating pressure. Even die setups to read release pressure testing. We have predictive engineering sotfware to show harmonics effects on muzzle position.

But some things we can carry over as universally relevant regardless of BR to SAAMI tolerance chambers setupsa inbetween; Comp to hunting. I gleaned bits of wisdom when it first was published. One was bullet alignment and neck tension and smoothness(Co friction) between bullet and neck were critical. As we know from basic tuning on a healthy node neck tension consistency and bullet to land have much more significant effects vs a tenth or two of powder charge.

Overall it does show when you can hold and control consistency between chamber and cartridge etc to a very high level the group consistency that is repeatably possible is extreme.

With our type of shooting we have to establish the way to get the most consistency when there are larger mechanical tolerances needed for high reliability.

 

[cajun]

I remember reading the article. One thing I will say the close br game is a lot different than the 1000 yd game.

 

[BigJohnH]

Questions: 1) Are all chambers exactly the same? 2) Are all brass cartridges produced to fit all chambers perfectly? 3) Does chamber pressure increase the fit of the cartridge to the chamber? If the answers are 1) no, 2) no, 3) yes then neck sizing is better for accuracy simply because the cartridge will not be " deformed " by full length sizing a cartridge back to factory specs.

 

[Orange Dust]

Questions: 1) Are all chambers exactly the same? 2) Are all brass cartridges produced to fit all chambers perfectly? 3) Does chamber pressure increase the fit of the cartridge to the chamber? If the answers are 1) no, 2) no, 3) yes then neck sizing is better for accuracy simply because the cartridge will not be " deformed " by full length sizing a cartridge back to factory specs.

You would not want to set up a F/L die that way unless loading for a semi auto or need the ammo to fit in several guns for some reason.

 

[Bart B]

Sierra Bullets did a lot of testing in the 1950's with different fired bottle neck cases to see what resizing method produced best accuracy. They soon learned that the better centered case necks were on case shoulders, accuracy improved. They knew the case shoulder was hard pressed and centered in the chamber shoulder when fired. Often the case shoulder was set back a thousandth or two from firing pin impact before the round fired. Didn't matter if the case body diameters were reduced a couple thousandths because they didn't touch the chamber except at their pressure ring about a tenth inch in front of the case extractor groove.

Measuring case neck runout on cases neck relative to case shoulder, smallest runout happened when fired cases were resized in dies whose shoulder centered in the die shoulder making the neck well centered on the case shoulder. Didn't matter how much the case body diameters were reduced.

Ferris Pindell (PPC cartridge family co-founder) was a tool and die machinist at Sierra who championed this idea. It was soon part of the trend in benchrest disciplines moving away from neck only to full length resized cases.

Was most interesting that good quality new rimless bottleneck cartridge cases often had necks well centered on their shoulders and were more accurate than neck only resizing routines. All new cases are full length sized.

 

[Orange Dust]

Sierra Bullets did a lot of testing in the 1950's with different fired bottle neck cases to see what resizing method produced best accuracy. They soon learned that the better centered case necks were on case shoulders, accuracy improved. They knew the case shoulder was hard pressed and centered in the chamber shoulder when fired. Often the case shoulder was set back a thousandth or two from firing pin impact before the round fired. Didn't matter if the case body diameters were reduced a couple thousandths because they didn't touch the chamber except at their pressure ring about a tenth inch in front of the case extractor groove.

Measuring case neck runout on cases neck relative to case shoulder, smallest runout happened when fired cases were resized in dies whose shoulder centered in the die shoulder making the neck well centered on the case shoulder. Didn't matter how much the case body diameters were reduced.

Ferris Pindell (PPC cartridge family co-founder) was a tool and die machinist at Sierra who championed this idea. It was soon part of the trend in benchrest disciplines moving away from neck only to full length resized cases.

Was most interesting that good quality new rimless bottleneck cartridge cases often had necks well centered on their shoulders and were more accurate than neck only resizing routines. All new cases are full length sized.

This has been my experience too, since I bought a gauge, and started to really play with die adjustment and measure the effect. I load more accurate ammo now. But I feel this is all for naught if you don't turn the necks in the first place. If you don't do this step, I don't feel it makes much difference which dies you use, you are leaving alot on the table, especially with big overbore magnums that are fussy to begin with. Proof of this is with the accuracy of factory loads in the Creed. Accuracy is "Good Enough" for most people. Many folks are reporting 1/2" groups @100 with factory ammo. I have always felt is I couldn't at least halve the 100yd group size of factory loads in any rifle I was doing something wrong and needed to find the problem. I still do.

 

[BountyHunter]

And it has changed too. The warehouse was over 25 years ago and lot has changed and been learned, particularily in the LR game.

 

[BountyHunter]

Sierra Bullets did a lot of testing in the 1950's with different fired bottle neck cases to see what resizing method produced best accuracy. They soon learned that the better centered case necks were on case shoulders, accuracy improved. They knew the case shoulder was hard pressed and centered in the chamber shoulder when fired. Often the case shoulder was set back a thousandth or two from firing pin impact before the round fired. Didn't matter if the case body diameters were reduced a couple thousandths because they didn't touch the chamber except at their pressure ring about a tenth inch in front of the case extractor groove.

Measuring case neck runout on cases neck relative to case shoulder, smallest runout happened when fired cases were resized in dies whose shoulder centered in the die shoulder making the neck well centered on the case shoulder. Didn't matter how much the case body diameters were reduced.

Ferris Pindell (PPC cartridge family co-founder) was a tool and die machinist at Sierra who championed this idea. It was soon part of the trend in benchrest disciplines moving away from neck only to full length resized cases.

Was most interesting that good quality new rimless bottleneck cartridge cases often had necks well centered on their shoulders and were more accurate than neck only resizing routines. All new cases are full length sized.

Pindell also did something else to center his bullets that was not widely known or discussed until a few friends let the cat out of the bag a couple years ago. He neck turned like normal and then went back and cut another few thousands off about .250 +- down. Then he fireformed. That second cut went from the outside of the case neck to the inside of the case neck and made a hard stop for the base of his bullets (all flat base at that time). I did it with a 300 wsm shooting 187 flat base BIB bullets about 10-12 years ago and it shot great.

I went thru the Sierra plant in Sedalia two years ago and went to the tunnel room. They just FL size now and let them rip with standard "known" loads. They also have added numerous machines and operations. One machine, one operator and one lot now. No more mix and matching bullets from multiple machines and operators ending in the same box.

 

[BountyHunter]

Questions: 1) Are all chambers exactly the same? 2) Are all brass cartridges produced to fit all chambers perfectly? 3) Does chamber pressure increase the fit of the cartridge to the chamber? If the answers are 1) no, 2) no, 3) yes then neck sizing is better for accuracy simply because the cartridge will not be " deformed " by full length sizing a cartridge back to factory specs.

The answer has been proven time and time again, no, no and lastly no UNLESS you are shooting loads well below SAAMI. You cannot stop brass expansion and without FL sizing you will get the click, hard extraction and hard loading eventually. That tells you that the case is moving all the time. More importantly, you DO NOT want to size back to "factory" specs. Factory specs have to be way under the chamber specs so they will fit ANY gun. With factory specs and repeated reloading you get case head separation most of the time eventually. You want to minimally resize until it will fit that one chamber, not every chamber in the world. You are trying for .002 shoulder and about .001 on bottom of the case. That is the only way you will get a case exactly the same every time. Think about it. A small base die is set up to give you at least .003 on the bottom of the case.

 

[Bart B]

I went thru the Sierra plant in Sedalia two years ago and went to the tunnel room. They just FL size now and let them rip with standard "known" loads. They also have added numerous machines and operations. One machine, one operator and one lot now. No more mix and matching bullets from multiple machines and operators ending in the same box.

I don't think Sierra ever mixed bullet lots. Arsenals did, even with 30 caliber 173 grain FMJBT match bullets.

Lapua did years ago evidenced by 3 or 4 different die prints on their rebated base match bullets and 3 or 4 distinctly different ogive and heel shapes visible in 50X optical comparitors

 

[BigJohnH]

You would not want to set up a F/L die that way unless loading for a semi auto or need the ammo to fit in several guns for some reason.

I don't know how you come to that conclusion, all full length sizing dies come with instructions on how to set them up for neck sizing! The very fact the brass is fire formed to the specific chamber and providing the headspace is correct it would only work well in the weapon fire formed to!

The answer has been proven time and time again, no, no and lastly no UNLESS you are shooting loads well below SAAMI. You cannot stop brass expansion and without FL sizing you will get the click, hard extraction and hard loading eventually. That tells you that the case is moving all the time. More importantly, you DO NOT want to size back to "factory" specs. Factory specs have to be way under the chamber specs so they will fit ANY gun. With factory specs and repeated reloading you get case head separation most of the time eventually. You want to minimally resize until it will fit that one chamber, not every chamber in the world. You are trying for .002 shoulder and about .001 on bottom of the case. That is the only way you will get a case exactly the same every time. Think about it. A small base die is set up to give you at least .003 on the bottom of the case.

I guess you should tell the die manufacturers not to include instructions for setup fl dies for neck sizing if it is so harmful. As far as clicking I have been neck sizing for many years and have never has such a sound nor have I had a cartridge fail because of nick sizing!

 

[Orange Dust]

I don't know how you come to that conclusion, all full length sizing dies come with instructions on how to set them up for neck sizing! The very fact the brass is fire formed to the specific chamber and providing the headspace is correct it would only work well in the weapon fire formed to!


I guess you should tell the die manufacturers not to include instructions for setup fl dies for neck sizing if it is so harmful. As far as clicking I have been neck sizing for many years and have never has such a sound nor have I had a cartridge fail because of nick sizing!

I think the confusion comes from nomenclature. You cannot "Neck Size" a cartridge with F/L Dies. The Term is "Partial Resize" which is what everyone essentially does. You have to have a neck sizing die to neck size. These dies don't support the case body for the most part and can and will induce runout. Especially the ones that use a bushing. I think we are really talking about the same thing and calling it something different unless I am missing something.

 

[Bart B]

Yes, partial full length sizing does size part of the neck. How much is determined by the clearance from case shoulder to the die shoulder.

This often squeezes the case body down enough to move its shoulder forward. If it's enough to not let the bolt close easily chambering the resized case, accuracy degrades because the bolt head won't go to its normal in battery position. May not be noticed unless all your groups at 100 yards are under 3/4 MOA

 

[Orange Dust]

Yes, partial full length sizing does size part of the neck. How much is determined by the clearance from case shoulder to the die shoulder.

This often squeezes the case body down enough to move its shoulder forward. If it's enough to not let the bolt close easily chambering the resized case, accuracy degrades because the bolt head won't go to its normal in battery position. May not be noticed unless all your groups at 100 yards are under 3/4 MOA

Also, the amount of taper in the body makes a difference. This method can be made to work pretty well if enough body taper is present. I still prefer F/L with a tiny .001-.002 shoulder bump. That, along with expanding in a mandrel die, has produced the best ammo for me, esp in magnums.