When to bump shoulder back?

[gasdoc09]

I have some Lapua 338LM brass that only gets fired out of one gun, a TRG42. I've been neck sizing only.

Using a Hornady comparator, I've measured the case length to the shoulder and (unsurprisingly) the brass is growing. Random sample of cases:

fired	AVG		1	2	3	4	5	6	7	8	9	10
0x	2.3224		2.322	2.321	2.322	2.322	2.324	2.323	2.322	2.322	2.324	2.322
1x	2.3267		2.327	2.326	2.327	2.327	2.327	2.327	2.327	2.326	2.327	2.326
2x	2.3284		2.329	2.329	2.328	2.329	2.329	2.328	2.328	2.328	2.328	2.328

Should I just leave it be until it gets hard to close the bolt, then knock it back a couple thousandths from whatever it is then?

 

[DRAM40A1]

I've never neck sized only. Get a good average and set your dies up, - .002.

 

[Deerhunter 28]

I've never neck sized only. Get a good average and set your dies up, - .002.

^^^^^^
This is what I do


PSE EVO 60 Lbs.
Blacked out

 

[waveslayer]

Check out wildernessmeans.com and he has a good article about case prep and bumping the shoulder back

 

[mr280]

The Book of Rifle Accuracy by Tony Boyer has a good section on this issue. I usually only full length re-size when my brass is hard to chamber or extract. That's just my opinion.

 

[ChrisGarrett]

I've got a 338LM TRG-42 that I've been reloading for for almost 8 years and I generally neck size using Redding bushing dies until I have to bump the shoulders back with either a FL bushing die, or my body die.

I'm on between 11-13 cycles for 80 pieces of Lapua brand and 8-9 cycles on 20 Norma cases. A neck split on a Norma after 2 cycles and I stuck a Lapua case in a kinetic puller and had to wrench it out.

When the bolt is 'hard' to close, that's when I FL/bump the shoulders back.

I define "hard" as 'thinking that the bolt's not going to close when chambering the round.' Snugly fitting carts aren't "hard."

Chris

 

[Fuzzball]

It's best to set the shoulders back just before you begin to feel resistance when closing the bolt; a jammed fit prestresses the action and that's detrimental to fine accuracy. Done that way, it's best to set the shoulders back 1 thou but no more than 2 thou.

 

[arnie19]

Also you must keep your locking lugs lubed or if you force too many rounds closed you risk galling the lug mating surfaces .

 

[Graham]

There's no advantage to neck sizing for a practical rifle.

 

[bigedp51]

At Germán A. Salazar's website "The Rifleman's Journal" as shooting buddy of Mr. Salazar said the following about competitive shooting and full length resizing.

"I get my best accuracy when the cartridge case fits the chamber like a rat turd in a violin case".

Meaning he full length resizes his cases and gives his cases a little wiggle room in the chamber to let the bullet be self centering in the bore and minimize any alignment errors that may come from the case.

 

[mb3]

Not sure if this help you but; I neck size (all ammo shot through one particular rifle) for about 8- 10 cycles of reloading, then check the brass with a Wilson case gauge, if needed bump the shoulders back (what ever is called for- usually .001 to .002 ish), and anneal. Repeat...

 

[bruddah]

At Germán A. Salazar's website "The Rifleman's Journal" as shooting buddy of Mr. Salazar said the following about competitive shooting and full length resizing.

"I get my best accuracy when the cartridge case fits the chamber like a rat turd in a violin case".

Meaning he full length resizes his cases and gives his cases a little wiggle room in the chamber to let the bullet be self centering in the bore and minimize any alignment errors that may come from the case.

I'm no expert, but why do so many competitors fire form their brass and neck size only? Especially for long range shooting I'd think that's the best way to get low ES (extreme spread) on your velocity.

 

[kmussack]

There's no advantage to neck sizing for a practical rifle.

+1

 

[Mad_Charlie]

Not sure if this help you but; I neck size (all ammo shot through one particular rifle) for about 8- 10 cycles of reloading, then check the brass with a Wilson case gauge, if needed bump the shoulders back (what ever is called for- usually .001 to .002 ish), and anneal. Repeat...

Anneal FIRST !!

 

[427Cobra]

I FL every single time, as does David Tubb, and the current BR world record holders at 100 yards(Mike Stinnet, we shoot at the same club) and the 1000 yard record holder, any/all claims of NS only being better have been proven wrong, and the ability to chamber a round without using the bolt handle as a reloading press makes any shooting outting uneventful.

 

[bruddah]

I FL every single time, as does David Tubb, and the current BR world record holders at 100 yards(Mike Stinnet, we shoot at the same club) and the 1000 yard record holder, any/all claims of NS only being better have been proven wrong, and the ability to chamber a round without using the bolt handle as a reloading press makes any shooting outting uneventful.

Interesting. Why do so many people do it then? Just to save on brass life?

 

[427Cobra]

I think it's just a technique that had its time and place, as for brass life I bought 500 Win 243/7-08 and reformed them into 260rem, some of that brass has over 30 firings, I don't shoot ballistic loads anymore, so the primer pockets of Win brass last a long time.

 

[Rprecision]

Been there tried that.

To answer your question, I was bumping the shoulder sometime around the second/third neck sizing. Much of the answer depends on fit, chamber pressure, brass, chamber size, Etc.

I know you didn’t ask, but I found a few things neck sizing for our discipline of shooting:

1. No real accuracy advantage
2. Always hoping I didn’t have a tight case and had to force one.
3. Slower bolt cycle time
4. No tangible change in brass life
5. No real savings in reloading time

I bump the shoulder back .002-.003" and full length size every loading. If, and that’s a fair "If" there was a gain to be had in accuracy for me it was ruined in reliability. There seems to be two theories as it pertains to neck sizing. (1) It allows tight consistent case measurements exact to the chamber. (2) Maintaining dimensions by full length sizing keeps better alignment over time (Brass flow, Etc.)

Neck sizing has its place and Bench rester’s use it all the time. There seems to be a bit of confusion / misinformation on how it’s deployed. For bench rest they use tight turned necks very often. This requires a very specific bushing to size the neck. Often the neck and body are sized in different operations. This is in part due to not having a die with the specific neck size and in part it’s believed to be more accurate. How this all crosses over to “regular” shooting disciplines is up to you, if at all. This is a great generality as dies have evolved and changed a lot in the past 10 years, hell 5 years. Hopefully that helps

 

[bruddah]

Been there tried that.

To answer your question, I was bumping the shoulder sometime around the second/third neck sizing. Much of the answer depends on fit, chamber pressure, brass, chamber size, Etc.

I know you didn’t ask, but I found a few things neck sizing for our discipline of shooting:

1. No real accuracy advantage
2. Always hoping I didn’t have a tight case and had to force one.
3. Slower bolt cycle time
4. No tangible change in brass life
5. No real savings in reloading time

I bump the shoulder back .002-.003" and full length size every loading. If, and that’s a fair "If" there was a gain to be had in accuracy for me it was ruined in reliability. There seems to be two theories as it pertains to neck sizing. (1) It allows tight consistent case measurements exact to the chamber. (2) Maintaining dimensions by full length sizing keeps better alignment over time (Brass flow, Etc.)

Neck sizing has its place and Bench rester’s use it all the time. There seems to be a bit of confusion / misinformation on how it’s deployed. For bench rest they use tight turned necks very often. This requires a very specific bushing to size the neck. Often the neck and body are sized in different operations. This is in part due to not having a die with the specific neck size and in part it’s believed to be more accurate. How this all crosses over to “regular” shooting disciplines is up to you, if at all. This is a great generality as dies have evolved and changed a lot in the past 10 years, hell 5 years. Hopefully that helps

Thanks for the feedback. At what distances do you shoot?

Do you have larger fluctuations in velocity when you FL size every time? I would think that would translate into a larger dispersion downrange?

 

[Rprecision]

Thanks for the feedback. At what distances do you shoot?

Do you have larger fluctuations in velocity when you FL size every time? I would think that would translate into a larger dispersion downrange?

We shoot out to 1500 with a 300WM when time and place affords.

I spend a majority of time inside 1000 and really inside 800

No, either way your doing it, provided your doing it right, you shouldnt see any ES SD change. The case volume change makes zero differance. If your sizing properly neck tension will be the same.

I loaded up 10 .308 round each FL and Neck sized. This was several years ago. I shot two 5 shot groups at 600 and a fellow shooter shot the other. I couldent pick out any notable advantage to the neck sized version. The disadvantages outweighed what ever gain there was, again thats for me. You may find something that appeals to you

 

[gasdoc09]

There's no advantage to neck sizing for a practical rifle.

Interesting, I thought case life was improved and accuracy improved, but this thread sure indicates otherwise. That's why I love this forum - learn something new all the time.

Thanks all!

 

[sakobob]

wouldn't f/l sizing in a long factory chamber shorten case life?
i.e if it grows say 4-5 tho and you push it back each time wouldn't the web area start to go?
i did notice this on a stock 300wm chamber,or is this just a belted issue.
went to just neck sizing and the pockets went long before the ring appeared,but before any big match i would bump
shoulders back .002.

 

[sakobob]

I bump the shoulder back .002-.003" and full length size every loading

how is this done, 2 dies? if so what type and the process to do it.
the part i don't understand, i guess is how do you f/l size while controlling shoulder bump ,
maybe this is a normal thing and it's a dumb question but please explain, thanks.

 

[shoot4fun]

There's no advantage to neck sizing for a practical rifle.

Agreed. Set you FL die up to bump every loading. I keep my brass annealed too so neck tension will always be consistent.
If you want to get really picky then get Harrell's to make you a "bump die". Send them three pieces of fired brass and they will build you a high quality die.

 

[harley_jeff]

I'm guessing a die such as the Redding Type S.. But I'll be waiting for the more experienced to chime in as well.

I bump the shoulder back .002-.003" and full length size every loading

how is this done, 2 dies? if so what type and the process to do it.
the part i don't understand, i guess is how do you f/l size while controlling shoulder bump ,
maybe this is a normal thing and it's a dumb question but please explain, thanks.