full length resize or neck size only ?
- Thread starter rebs
- Start date
Both Sinclair and Hornady market "bump / headspace" gauges that can be used with for multiple calibers via their inserts to measure the degree of shoulder set back. These also require a reasonably precise caliber to use.
I personally like the Hornady tool to measure the amount of shoulder bump and set my full sizing die accordingly. I use Skip Shims (available at Sinclair) to make adjustments to shoulder bump if necessary as the cases harden over time with repeated loadings.
RCBS makes a caliber specific tool for this purpose but it pricey especially if you reload more than one caliber.
Wilson also make a "case gauge" for indicating shoulder set back but it's more difficult to use if you want to measure precise shoulder set back. However it's an effective qualitative tool by comparing a fire case to a size case.
Whatever tool you choose this work only if you dedicate a group of cases to a specific rifle since what you are attempting to achieve is a .001 to .002" shoulder set back (bolt rifles) from a fired case in a specific rifle.
A loaded round should fit in a chamber like a rat turd in a violin case. 
Kevin Thomas
Lapua USA
"There's two very common misconceptions that you've expressed here, and I'd like to address them both. One , that N/S extends the life of the brass. As I said, if done properly, F/L sizing gives you every bit as long of case life as N/S can, but without all the additional headaches that go hand in hand with neck sizing. You will have problems if you stick to neck sizing. It's not a question of if but of when. I tend to believe in Murphy in these things, and he'll usually find you when you can least afford a visit from him. And Two, that full length sizing somehow produces less accurate ammo than neck sizing. It doesn't, and is generally the other way around. Virtually all accuracy labs that I'm aware of use nothing but full length sizing for all their testing, and accuracy is what most reloader's dream of. I've fired literally hundreds of thousands of ten shot groups, with well over 95% of them staying far below the 1/2 MOA mark. In fact, when a rifle wouldn't consistently hold 1/2 MOA or under, I scrapped the barrel, as I could no longer use it for test purposes. All of that ammo was full length sized, NEVER neck sized, as it had to work in a variety of different guns. MY predecessor at Sierra, Jim Hull, used to say that a loaded round should fit in a chamber," like a rat turd in a violin case." Jim had a way with words, and creating visual images. But the idea is that it should fit freely, without binding or jamming when chambered. Forget the nonsense about N/S ammo giving better accuracy, because it's exactlyvariety that, nonsense. A few isolated examples of individual guns or groups don't change that, and it's the long run averages that count."variety
The Rifleman's Journal
Germán A. Salazar
"a full-length sized case in which the neck is also fully sized. There is clearance at the neck and in the body of the case, the closest fit anywhere is the bullet in the throat. If the neck to bullet concentricity is good (although it needn't be perfect), then the bullet will find good alignment in the throat and the case body and neck will have minimal influence. Let's not forget that the base of the case is supported by the bolt face or the extractor to a certain degree as well; this is yet another influence on alignment. As you can see, there are several points from base to bullet that can have an effect. My procedure is to minimize the influence of those that I can control, namely the case body and neck, and let the alignment be dictated by the fit of the bullet in the throat and to some extent by the bolt's support of the base. Barring a seriously out of square case head, I don't think the bolt can have a negative effect on alignment, only a slightly positive effect from minimizing "case droop" in the chamber. Given that a resized case will usually have a maximum of 0.001" diametrical clearance at the web, this isn't much of a factor anyway.
In conclusion, I believe that allowing the bullet to find a relatively stress-free alignment in the throat by full length sizing (including the neck) and turning necks to enhance concentricity gives the bullet the best probability of a well-aligned start into the rifling."
Kevin Thomas
Lapua USA
"There's two very common misconceptions that you've expressed here, and I'd like to address them both. One , that N/S extends the life of the brass. As I said, if done properly, F/L sizing gives you every bit as long of case life as N/S can, but without all the additional headaches that go hand in hand with neck sizing. You will have problems if you stick to neck sizing. It's not a question of if but of when. I tend to believe in Murphy in these things, and he'll usually find you when you can least afford a visit from him. And Two, that full length sizing somehow produces less accurate ammo than neck sizing. It doesn't, and is generally the other way around. Virtually all accuracy labs that I'm aware of use nothing but full length sizing for all their testing, and accuracy is what most reloader's dream of. I've fired literally hundreds of thousands of ten shot groups, with well over 95% of them staying far below the 1/2 MOA mark. In fact, when a rifle wouldn't consistently hold 1/2 MOA or under, I scrapped the barrel, as I could no longer use it for test purposes. All of that ammo was full length sized, NEVER neck sized, as it had to work in a variety of different guns. MY predecessor at Sierra, Jim Hull, used to say that a loaded round should fit in a chamber," like a rat turd in a violin case." Jim had a way with words, and creating visual images. But the idea is that it should fit freely, without binding or jamming when chambered. Forget the nonsense about N/S ammo giving better accuracy, because it's exactlyvariety that, nonsense. A few isolated examples of individual guns or groups don't change that, and it's the long run averages that count."variety
The Rifleman's Journal
Germán A. Salazar
"a full-length sized case in which the neck is also fully sized. There is clearance at the neck and in the body of the case, the closest fit anywhere is the bullet in the throat. If the neck to bullet concentricity is good (although it needn't be perfect), then the bullet will find good alignment in the throat and the case body and neck will have minimal influence. Let's not forget that the base of the case is supported by the bolt face or the extractor to a certain degree as well; this is yet another influence on alignment. As you can see, there are several points from base to bullet that can have an effect. My procedure is to minimize the influence of those that I can control, namely the case body and neck, and let the alignment be dictated by the fit of the bullet in the throat and to some extent by the bolt's support of the base. Barring a seriously out of square case head, I don't think the bolt can have a negative effect on alignment, only a slightly positive effect from minimizing "case droop" in the chamber. Given that a resized case will usually have a maximum of 0.001" diametrical clearance at the web, this isn't much of a factor anyway.
In conclusion, I believe that allowing the bullet to find a relatively stress-free alignment in the throat by full length sizing (including the neck) and turning necks to enhance concentricity gives the bullet the best probability of a well-aligned start into the rifling."
I switched from neck sizing to full length sizing . My cases would get shorter from expansion so that would leave to much wiggle room from base to shoulder finding base to ogive was never accurate . After full sizing and knowing my bolt face to datum ( shoulder ) measurement , I size to .001 - .002 no more or less . Now I can get a very accurate measurement from bolt face to ogive , enabling me to jump , touch or jam your reloads . Full length resizing has worked much better for me . I use the closed bolt method using just the bolt housing and double checked with a Go Gage and shims . Also to find the ogive using the closed bolt method. Gives me repeatable measurements , very accurate .
So here's a question. I fire-formed 50 Lapua cases 308 Win. and measured their CBTS:
o 1.6240" 1
o 1.6245 17
o 1.6250 23
o 1.6255 7
o 1.6260 2
I FL resized the cases to a CBTS of 1.625" only. So some were bumped a little and others not. They were fired again during incremental load testing (so 2x fired). I measured 40 of them:
o 1.6245 9
o 1.6250 13
o 1.6255 16
o 1.6260 2
I keep hearing about bumping 1-2 thou. However it would seem to me that such a big bump would continually shorten the cases. To what length would you size the 2x fired brass?
o 1.6240" 1
o 1.6245 17
o 1.6250 23
o 1.6255 7
o 1.6260 2
I FL resized the cases to a CBTS of 1.625" only. So some were bumped a little and others not. They were fired again during incremental load testing (so 2x fired). I measured 40 of them:
o 1.6245 9
o 1.6250 13
o 1.6255 16
o 1.6260 2
I keep hearing about bumping 1-2 thou. However it would seem to me that such a big bump would continually shorten the cases. To what length would you size the 2x fired brass?
Last edited:
Dusty Stevens
Shiner
Your cases are not fully formed yet. Dont bump them until you feel the slight crush on a stripped bolt then bump them .002 short of that one. Some bump and some dont at this point
I’ve done both and I shoot competitive Benchrest. I full length resize every time.
All I have say is listen to Boyd!!!
Bart
All I have say is listen to Boyd!!!
Bart
That's why I have just been bumping the long ones only very slightly. However, my point is I don't see anything close to 1-2 thou of case growth per firing. So even once fully fire formed I'd expect a bump of 1-2 thou not to return on firing. Maybe the lengthening upon firing increases as the cases form?
Al Lu
Gold $$ Contributor
I always full size and in my quest to get a full size die (6mm BR)I was advise to call Harrells to get a full size die? The gentleman at Harrells tells me to send him a set of three time fired brass case neck size only 
.
Can you understand the confusions this can create? What came first chicken or the egg...
. Can you understand the confusions this can create? What came first chicken or the egg...
Everyone knows the chicken came first “I always full size and in my quest to get a full size die (6mm BR)I was advise to call Harrells to get a full size die? The gentleman at Harrells tells me to send him a set of three time fired brass case neck size only
Can you understand the confusions this can create? What came first chicken or the egg...
Just for a comparison, I just formed new Lapua Brass from 6.5 to 6x47L on Forster FL dies. Shot these first time with 107SMK at slight touch. Shoulder moved out consistently.003”three thousandths”.
I always full size and in my quest to get a full size die (6mm BR)I was advise to call Harrells to get a full size die? The gentleman at Harrells tells me to send him a set of three time fired brass case neck size only
Can you understand the confusions this can create? What came first chicken or the egg...
Lots of reloaders have no idea what a fully fireformed case is. They take a piece of once fired brass and set up a shoulder bump. As long as a piece of fired brass chambers easily it is not fully fireformed and your die should be set to only size the neck. It is easy to do with a full length die. Just back the die off and size a piece of fired brass. First cycle you may not even touch the neck but by turning the die in a little and cycling the press you will see when you start to size the neck. Once the majority of the neck is sized and you haven't touched the shoulder you have the die set to neck size the rest of your cases. Load them, shoot them and cycle a piece of the fired brass. Repeat until a piece of fired brass chambers tight. That is fully fireformed brass. Usually at least 3 firings. Then you can set up your shoulder bump or send 3 pieces to harrells. Let them know it chambers tight.
Dusty Stevens
Shiner
I always full size and in my quest to get a full size die (6mm BR)I was advise to call Harrells to get a full size die? The gentleman at Harrells tells me to send him a set of three time fired brass case neck size only
Can you understand the confusions this can create? What came first chicken or the egg...
You can neck size with a fl die
I’m not sure if this was in relation to my post or not. Nonetheless...
In my case, given this rifle is a Blaser straight pull action, I can’t do all the stripped bolt sort of testing. I’m merely observing case growth after each firing. (I have some 3x fires RWS brass that has only ever been neck sized which I can check for comparison.) I’m only seeing very minor case growth between 1x fired and 2x fired. I bumped the few longer ones (it should have been just 9 of 50) just a smidgeon to align the batch a little better. I can back the die off a little and essentially just neck size them this next time to see what happens. I don’t get to feel bolt close or lift with this action in the same way with a conventional bolt action rifle.
(I hadn’t deprimed the 2x fired cases prior to measurement but can do so.)
I always full size and in my quest to get a full size die (6mm BR)I was advise to call Harrells to get a full size die? The gentleman at Harrells tells me to send him a set of three time fired brass case neck size only
Can you understand the confusions this can create? What came first chicken or the egg...
You don't need a neck die to produce 3x fireformed brass. After each firing just decap, prime, add powder, drop a bullet in the unsized brass, and fire again. It doesn't matter that the bullet isn't held in the neck by tension.
J F Johannes
AKA "RatRifle"
Please explain. This sounds a little dangerous to me. P.S. Not trying to start a fight, just would like to know the reasoning behind this.
Jim
Has anyone ever done a test on if the amount of shoulder bump effects accuracy?
With a full length resize case the case body is not contacting the chamber walls as German Salazar described in my post above. This means the only part of the case that contacts the chamber is the case shoulder. And the amount of shoulder bump and head clearance will help if the base of the case is tilted after the first firing. Meaning if the base of the case is tilted a little extra amount of shoulder bump/head clearance is to your benefit.
Below is Germán Salazar's responce to a question about partial full length resizing and saying a totally full length resized case has wiggle room for the bullet to be self aligning with the bore. Meaning the case body and base has no effect on bullet alignment and the cartridge should fit the chamber like a rat turd in a violin case.
The Rifleman's Journal
Germán A. Salazar
"a full-length sized case in which the neck is also fully sized. There is clearance at the neck and in the body of the case, the closest fit anywhere is the bullet in the throat. If the neck to bullet concentricity is good (although it needn't be perfect), then the bullet will find good alignment in the throat and the case body and neck will have minimal influence. Let's not forget that the base of the case is supported by the bolt face or the extractor to a certain degree as well; this is yet another influence on alignment. As you can see, there are several points from base to bullet that can have an effect. My procedure is to minimize the influence of those that I can control, namely the case body and neck, and let the alignment be dictated by the fit of the bullet in the throat and to some extent by the bolt's support of the base. Barring a seriously out of square case head, I don't think the bolt can have a negative effect on alignment, only a slightly positive effect from minimizing "case droop" in the chamber. Given that a resized case will usually have a maximum of 0.001" diametrical clearance at the web, this isn't much of a factor anyway.
In conclusion, I believe that allowing the bullet to find a relatively stress-free alignment in the throat by full length sizing (including the neck) and turning necks to enhance concentricity gives the bullet the best probability of a well-aligned start into the rifling."
With a full length resize case the case body is not contacting the chamber walls as German Salazar described in my post above. This means the only part of the case that contacts the chamber is the case shoulder. And the amount of shoulder bump and head clearance will help if the base of the case is tilted after the first firing. Meaning if the base of the case is tilted a little extra amount of shoulder bump/head clearance is to your benefit.
Below is Germán Salazar's responce to a question about partial full length resizing and saying a totally full length resized case has wiggle room for the bullet to be self aligning with the bore. Meaning the case body and base has no effect on bullet alignment and the cartridge should fit the chamber like a rat turd in a violin case.
The Rifleman's Journal
Germán A. Salazar
"a full-length sized case in which the neck is also fully sized. There is clearance at the neck and in the body of the case, the closest fit anywhere is the bullet in the throat. If the neck to bullet concentricity is good (although it needn't be perfect), then the bullet will find good alignment in the throat and the case body and neck will have minimal influence. Let's not forget that the base of the case is supported by the bolt face or the extractor to a certain degree as well; this is yet another influence on alignment. As you can see, there are several points from base to bullet that can have an effect. My procedure is to minimize the influence of those that I can control, namely the case body and neck, and let the alignment be dictated by the fit of the bullet in the throat and to some extent by the bolt's support of the base. Barring a seriously out of square case head, I don't think the bolt can have a negative effect on alignment, only a slightly positive effect from minimizing "case droop" in the chamber. Given that a resized case will usually have a maximum of 0.001" diametrical clearance at the web, this isn't much of a factor anyway.
In conclusion, I believe that allowing the bullet to find a relatively stress-free alignment in the throat by full length sizing (including the neck) and turning necks to enhance concentricity gives the bullet the best probability of a well-aligned start into the rifling."
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