Partial Neck Sizing

[coolbox]

The last topic on this subject was about 5 years ago...
When I started reloading for 308win FTR 2 years ago, I thought of only partially sizing necks in fire formed brass to avoid uneven neck tension due to uneven brass thickness (I am not turning necks). I size down to 35% neck depth (one third). Most of the 185juggs' bearing surface is covered, but I was not quite focussing on that. I was (still am) just a novice. Would it help to size further, say 50% or 60% of neck, or is it ok as is. I would mainly use Berger 155.5 fullbore, 185juggs and 200.20x. I use redding competition dies, and use 0.336 bushing.

To add, my chamber neck is .344, and I shoulder bump 2 thou, with 0.343 bushing in a Forester shoulder bump die. Then i further size the neck with the Redding.

 

[liljoe]

This should get it started.
Joe

 

[marchboom]

Just my non-expert opinion but I would want more neck-to-bullet contact than just approx .100". This would keep the bullet from being bumped out of line with the case axis. Also, you have greatly reduced the neck tension that helps the powder to build up to the necessary pressure needed. I would seat the bullet to at least 80% of the neck. This would keep the bullet away from the dreaded donut.

 

[Bc'z]

My non competitive opinion....
Why dont you just use the Redding die and do it in 1 step?
The bushing is only going to size a portion of the neck. And you'll get the desired shoulder bump in 1 motion.
No interference from a doughnut due to neck only getting partially sized.

FWIW I quit neck sizing

 

[sdean]

The last topic on this subject was about 5 years ago...
When I started reloading for 308win FTR 2 years ago, I thought of only partially sizing necks in fire formed brass to avoid uneven neck tension due to uneven brass thickness (I am not turning necks). I size down to 35% neck depth (one third). Most of the 185juggs' bearing surface is covered, but I was not quite focussing on that. I was (still am) just a novice. Would it help to size further, say 50% or 60% of neck, or is it ok as is. I would mainly use Berger 155.5 fullbore, 185juggs and 200.20x. I use redding competition dies, and use 0.336 bushing.

To add, my chamber neck is .344, and I shoulder bump 2 thou, with 0.343 bushing in a Forester shoulder bump die. Then i further size the neck with the Redding.

This something you should test on your own target.
Look up 30 wolf pup and you see how much neck is needed.

 

[Bill Norris]

Saw this post way back from 2012.

 

[K22]

My non expert / non competitive opinion from a hunter's perspective. This topic has been discussed a lot on this forum and various other forums. Also there are a bunch of video's on You Tube addressing this topic and there is a range of opinions regarding the optimum sizing methods.

Far be from me to say anything counter to Mr. Tony Boyer who truly is an expert judging from his competitive success.

I've been reloading for close to 50 years now which does not make me an expert. I've tried all the approaches, neck sizing, partial sizing, and full sizing attempting to find the optimum method for my purposes.

After trying different approaches I subscribed to German Salazar's method which means full sizing with a .001 to .002" shoulder bump using conventional dies. To accomplish this properly you need a reliable bump gauge and caliper. His approach made the most sense to me and the simplest approach to producing adequately sized cases.

In my experience, this method produces flawless functioning reloads which is a prime consideration for a hunter. Precision is important to me also since I hunt varmints and predators and I have found no loss in accuracy or case life with properly full sized cases.

I control neck tension by using various size expander balls with my conventional full length sizing dies - probably not the best way but it works reasonable well. I've never experience any 'donuts" with my reloads.

I do not anneal or use bushing dies but understand the benefits of these processes for the kind of precision needed in competitive shooting. But I don't want to spend any more time or money on reloading processes than I have to in order to produce adequate reloads for my purpose. I try to keep things as simple as possible.

The guys that I know that use bushing dies also turn necks since the goal is the most uniform neck tension possible. I don't know how you can achieve that without turning necks but this a subject I'm not well versed in and will yield to others on this topic.

You may want to try just a few rounds full sized with the aforementioned shoulder bump and see what the target tells you. My 308 Rem 700 shoots consistent groups in the 1/2 moa range with this method of sizing.

 

[Dusty Stevens]

Main thing you gotta do is size it far enough your pressure ring doesnt go into the unsized portion. It really doesnt matter if you size 80% or 95% at that point its doing the same thing. Leave a bit to center it up and youll be happy

 

[Tommie]

Yeah right. Like Tony Boyer knows anything about shooting tiny groups...

 

[Fuj]

Another way to look at it. I've been using the Lee collet neck
sizer for some time now. I make my own mandrels as needed.
My latest Cat I had found that a 7-08 collet die would work with
this project. For some reason as I was seating the very first
batch of bullets, the bullets would push in easily for about the
first .080" then resistance after that. I thought I screwed up my
mandrel but was not the case. Here I had found out that Lee
modified the collet to not sqeeze the beginning of the neck. So
basically my neck had two tensions. I was going to hone out the
step in the collet, but so far my targets look good. Once I'm really
settled in, I'll pick up a replacement collet, hone that, and do a test.

 

[coolbox]

Thank you all for the replies.

 

[johara1]

It seems stupid to say TB. leave 30% of the neck for alignment... he turns necks, so he may gain something. You don't turn necks so no matter what you do it will not improve your alignment.... jim

 

[Laurie]

It seems stupid to say TB. leave 30% of the neck for alignment... he turns necks, so he may gain something. You don't turn necks so no matter what you do it will not improve your alignment.... jim

Use Wilson bushing neck-sizers and a significant amount of lower neck is left unsized. My bench rest shooting friends just laughed when I asked if this is normal / has downsides, yes / no being the answers. I have a 7mm-08 F-Class rifle whose brass has used a combination of Redding body die + Wilson hand bushing neck die + mandrel expander for every one of the the 2,000 plus rounds through it and the partially sized and not unduly long 7-08 Rem neck manages to consistently produce 0.4" 5-shot group averages and c. 0.3" averages with one load I use.

Neck turning has two possible objectives which may be separate or combined depending on the rifle and its use. Full-house BR case prep and operation often (usually?) sees chambers that need seriously thinned necks this having been found to give better results than chambers designed for normal thickness necks. So 220 Russian brass that starts at around 0.012" wall thickness IIRC ends up at around 0.0085" after turning to match a suitably 'tight-neck'chamber with around 0.003" overall clearance on a loaded round. The 6BR brass I start with for 30BR is around 0.0125-0.013" and ends up turned to 0.0095" to suit the chamber.

The other reason is consistency / concentricity - ie an ideal of nil thickness variation around the neck. Standards have changed massively for the better with the higher grade factory products in recent years in this respect. I regularly measure 25 case samples of new Lapua brass, occasionally Norma (and more recently Peterson since it appeared). This is done on the neat Sinclair assembly of a Starrett 0.0001" ball micrometer mounted on a small steel stand. I take three readings on each case at approximately equidistant points around the neck at the same depth - ie 75 readings on my usual sample size. You get two findings from this:

1) the extreme spread of the entire sample - the lowest and highest readings of the 75.

2) variations present in individual cases - highest minus lowest readings of the threesome.

These days, variation 1) is commonly not much over 0.001" and variation 2) ranges from nil to a bit under 0.001" with the usual bell curve distribution - one nil and one at 0.0009 or 0.001" outliers with most in a relatively small range covering 0.0005" in the middle.

Now go back to the days when Creighton Audette and the greats of the early US BR scene were trying to make US brass of the day work. They were measuring and trying to correct HUGE neck thickness variations - 2 to three thou' variation around a neck on an out of the packet case was often regarded as 'good'!

When I first got into neck turning as a 'clean'up' operation for minimum SAAMI chambers in 223/308 FTR rifles, I'd see the common advice to set the cutter so that you only remove brass from the 'high side' of the case with the largest reading and use throughout. This made no sense with most of the brass I was using - the tool blade didn't touch anything on many cases and did a mild polish only on as tiny patch on others.

We are using factory brass today out of the box that with a bit of judicious measurement and batching is as consistent as many BR competitors were using a generation or two ago. Maybe thicker - but that's needed for the larger dimension chambers we use anyway - but with really small variability.

Sure, today's top BR shooters use prepped brass with almost nil variability, but that's the name of the BR game. Nevertheless, the gap between 'us' (F-Classers, Varminters, PRS, anybody shooting a well chambered and built custom or simply quality-rebarrelled varmint or tactical rifle) has narrowed appreciably, so longstanding BR techniques proven over decades by people like Tony Boyer aren't at all inappropriate for the rest of us. Well, at least until you compare PPU brass to Lapua (as I have for 6.5mm Grendel) - but there's a simple answer to that issue usually even if the supplier's bill hurts the wallet.

 

[johara1]

Use Wilson bushing neck-sizers and a significant amount of lower neck is left unsized. My bench rest shooting friends just laughed when I asked if this is normal / has downsides, yes / no being the answers. I have a 7mm-08 F-Class rifle whose brass has used a combination of Redding body die + Wilson hand bushing neck die + mandrel expander for every one of the the 2,000 plus rounds through it and the partially sized and not unduly long 7-08 Rem neck manages to consistently produce 0.4" 5-shot group averages and c. 0.3" averages with one load I use.

Neck turning has two possible objectives which may be separate or combined depending on the rifle and its use. Full-house BR case prep and operation often (usually?) sees chambers that need seriously thinned necks this having been found to give better results than chambers designed for normal thickness necks. So 220 Russian brass that starts at around 0.012" wall thickness IIRC ends up at around 0.0085" after turning to match a suitably 'tight-neck'chamber with around 0.003" overall clearance on a loaded round. The 6BR brass I start with for 30BR is around 0.0125-0.013" and ends up turned to 0.0095" to suit the chamber.

The other reason is consistency / concentricity - ie an ideal of nil thickness variation around the neck. Standards have changed massively for the better with the higher grade factory products in recent years in this respect. I regularly measure 25 case samples of new Lapua brass, occasionally Norma (and more recently Peterson since it appeared). This is done on the neat Sinclair assembly of a Starrett 0.0001" ball micrometer mounted on a small steel stand. I take three readings on each case at approximately equidistant points around the neck at the same depth - ie 75 readings on my usual sample size. You get two findings from this:

1) the extreme spread of the entire sample - the lowest and highest readings of the 75.

2) variations present in individual cases - highest minus lowest readings of the threesome.

These days, variation 1) is commonly not much over 0.001" and variation 2) ranges from nil to a bit under 0.001" with the usual bell curve distribution - one nil and one at 0.0009 or 0.001" outliers with most in a relatively small range covering 0.0005" in the middle.

Now go back to the days when Creighton Audette and the greats of the early US BR scene were trying to make US brass of the day work. They were measuring and trying to correct HUGE neck thickness variations - 2 to three thou' variation around a neck on an out of the packet case was often regarded as 'good'!

When I first got into neck turning as a 'clean'up' operation for minimum SAAMI chambers in 223/308 FTR rifles, I'd see the common advice to set the cutter so that you only remove brass from the 'high side' of the case with the largest reading and use throughout. This made no sense with most of the brass I was using - the tool blade didn't touch anything on many cases and did a mild polish only on as tiny patch on others.

We are using factory brass today out of the box that with a bit of judicious measurement and batching is as consistent as many BR competitors were using a generation or two ago. Maybe thicker - but that's needed for the larger dimension chambers we use anyway - but with really small variability.

Sure, today's top BR shooters use prepped brass with almost nil variability, but that's the name of the BR game. Nevertheless, the gap between 'us' (F-Classers, Varminters, PRS, anybody shooting a well chambered and built custom or simply quality-rebarrelled varmint or tactical rifle) has narrowed appreciably, so longstanding BR techniques proven over decades by people like Tony Boyer aren't at all inappropriate for the rest of us. Well, at least until you compare PPU brass to Lapua (as I have for 6.5mm Grendel) - but there's a simple answer to that issue usually even if the supplier's bill hurts the wallet.

I guess it boils down on how much effort you want to put into loading and what you are content with to be competitive....... Most are trying to convince themselves and others that the extra work isn't needed and skip steps in precision loading. .3 and .4 100 yd. groups isn't competitive at BR...... jim

 

[Bc'z]

I guess it boils down on how much effort you want to put into loading and what you are content with to be competitive....... Most are trying to convince themselves and others that the extra work isn't needed and skip steps in precision loading. .3 and .4 100 yd. groups isn't competitive at BR...... jim

.3" @ 600 is 2", @ 1000 it's a 3" group.
If you follow @Laurie at all you'd probably have come to this conclusion without my help.

 

[johara1]

.3" @ 600 is 2", @ 1000 it's a 3" group.
If you follow @Laurie at all you'd probably have come to this conclusion without my help.

I wish it worked that way, I always figured a repeatable .1 at 100 with a good barrel would let me shoot 2" or less under good conditions at 1000..... jim

 

[Bc'z]

I wish it worked that way, I always figured a repeatable .1 at 100 with a good barrel would let me shoot 2" or less under good conditions at 1000..... jim

Ya got a point there. Lol

 

[johara1]

tuning is paramount, usually the best tuned rifle will shoot through the wind better...... theist tuned hummer barrel trumps all.... jim

 

[Laurie]

I guess it boils down on how much effort you want to put into loading and what you are content with to be competitive....... Most are trying to convince themselves and others that the extra work isn't needed and skip steps in precision loading. .3 and .4 100 yd. groups isn't competitive at BR...... jim

It's not a BR rifle, rather a budget (in relative terms) F-Class job. (Savage PTA and trigger exactly as out of the factory, trigger set at 1.25lb pull for reliability; Dolphin Gun Co. aluminium alloy chassis F stock; 31-inch 9 twist Bartlein in F profile and I prefer to shoot off a bipod rather than front-rest - with interchangeable forends I can use either method of support.)

It's good enough to have seen me win 500 and 600 yard F/Open matches in a very competitive club scene with a couple of possibles at 500 and high V-counts. Remember in the UK we shoot pairs with the 45-second rule, so that's usually a recalibrate windage for every shot and this on one of the windy British Isles' windiest ranges. At 300 yards I have shot 19 Vs in a match so that's 19 in under half-MOA group over a 30-minute shoot period (with manual marking - e-targets will help here from 2021 by reducing the between-shot intervals).

Next time you think BR group size why not replicate our F-shooting regime? I'd love to see what 20-round group size you'd get with a mandatory 2-3 minute delay between shots and the shot having to be be taken within a 45-second window irrespective of what the mirage and / or the wind is doing.

Given the combination of the range's wind conditions and the shooting regime constraints, the rifle, or more precisely its cartridge, is no longer fully competitive at even 500 yards now. Up against 284s, 7mm SAUMs and WSMs, 300 WSMs and even a 300 RUM for a season, the 160gn Sierra TMK at 2,865 fps sees too many shots sliding out of the V into the 5 ring, and too many leaking out into the 4 when the ballistically more capable numbers just keep them on the right side of the ring. Sadly its owner is no longer fully competitive either as my wind-reading skills have atrophied somewhat from my peak which doesn't help although every now and then I have a good day when I make fewer bad calls than the competition.

 

[johara1]

Every game has it own sets of problems as I at br. would like to have marked shots, and big targets...... The wind blows here too.... jim