How often do you bump the shoulder back?

[CleanShot]

Hello

I'm a newbie reloader so I've been trying to read and consume as much information as possible. I'm a bit confused on this topic however.

I noticed most people say neck sizing helps extend your cartridge life over full resizing. Ok so neck size it is. But then I noticed some people neck size without pushing the shoulder back each time. They only bump the shoulder every 3rd time or so. I've heard this called "bump sizing".

Any opinions on this?

Thanks
Sam

 

[Lefty7mmstw]

I fl size every time. I want the brass to enter the chamber at the same dimensions for every firing. I'll sacrifice a shot or two of brass life for this.

Fl sized brass will often index in the chamber more squarely too (and hence be more accurate), since it won't bind on any out of round dimension that your rifle likely has. It will index on the case head and the headspace point, whether it is a belt of shoulder and that is it, every time... Not so with and out of round chamber and neck sized ammo... It will index at the above points and/or anywhere the case touches an out of center/ round point in the chamber. If the brass isn't turned to the exact rotation it was on the previous shot, it will not be square to the world.

My last 7stw barrel was a case in point for this, as it shot into .5 to .6 moa with fl sized ammo... I tried to neck size or partial fl size the bras to save brass life ( the chamber was cut extremely long) and the accuracy fell to 1.5 moa. A more extreme difference than usual to be sure, but it can and often does happen.

 

[Broz]

A properly set full length die or body die will only bump the shoulder if it has grown out of spec and needs it. I full size each time and keep shoulders back to spec at about .002" from headspace. This will insure all your ammo is the same all the time. A case that closes firm or hard will not usually shoot at the same speed as one that is head spaced and sized correctly.

Jeff

 

[FearNoWind]

Llkewise, I FL resize every time - for all the reasons previously listed. But I do use a Redding Competition Shell Holder Set to adjust the shoulder so I get precisely the amount of shoulder set back I need while avoiding over working the brass.
I do neck sizing using the Redding neck bushing die to also minimize working the bras more than necessary.

 

[MagnumManiac]

OK, everyone's told you what they do, here is the why.
FL sizing, as per the die instructions, reduces the case back to, or close to, MINIMUM SAAMI specs, therefore, that case should fit in EVERY rifle chamber out there, now, this will cause short case life because the shouldecr expands to meet the chamber time after time, and the case stretches just forward of the web, eventually splitting in two.
The idea of partial FL sizing, gives the case enough wiggle room to chamber easily, but it doesn't allow the case to expand/stretch at the web, .002" shoulder bump is ample to allow good case life and easy chambering, it also only sizes the ENTIRE case a minimal amount.
You can switch it up by sizing the body only with a body die, then size the neck with a bushing, or just use a FL die adjusted correctly to only bump the shoulder.

Hope this helps.
gun)

 

[rcoody]

I have tried them all.

Now I have settled down to this method.

For my bolt action hunting guns I use a full length sizing die set to 1.5 to 2 thousands shoulder bump. I want all these rounds to chamber easily.

For my bolt action range guns I neck size and about every 5 firings I use a body die.

For my ar range gun I use a full length sizing die set to a 3 thousands shoulder bump.

I anneal after every 5 firings.

 

[Gene]

I want my hunting cartridges FL sized every time. This insures positive chambering - especially when the bull or buck of a lifetime stands in front of you.

Caveat: Over sizing brass can create dangerous excess headspace. There are several ways to determine the amount of bump. I use the Redding instant indicator. With this, you can measure the shoulder before sizing, and again after sizing. The dial will tell you how much. Usually 1-2 thou is enuf.

 

[tbrice23]

I fl size every time. I want the brass to enter the chamber at the SAME dimensions for every firing. I'll sacrifice a shot or two of brass life for this.
.

+1
Consistency is necessary for precision and predictable accuracy.
I could never see how extra stress on the action by only neck sizing is good for anything except wear on the locking lugs.

Also, I will NOT tolerate having to struggle chambering a round in the field in a hunting situation.

 

[Bart B]

Depending on the way folks believe a cartridge is positioned in the chamber when it fires, they'll use the tool and set it up for use to do make the resized case best fit the chamber for their objectives in using that reload.

Which is why there's several tool selection, setup and use situations across all reloaders.

I knew a guy back in the '50's who neck sized his .30-06 cases from his M1917 Enfield by squeezing their necks down a bit with a 3/8ths inch drill chuck. Deprimed cases using a 16d nail with it tip ground down to fit through the flash hole. Seated primers with a drill press and a flat tip rod in it pressing them in the primer pocket. Used a cut off case leveled with 4831 powder to measure charges. Seated bullets with that same drill press with a steel tube chucked up to a depth set by the vertical stop on the drill press. He got his deer every season.

 

[FearNoWind]

Depending on the way folks believe a cartridge is positioned in the chamber when it fires, they'll use the tool and set it up for use to do make the resized case best fit the chamber for their objectives in using that reload.
......
I knew a guy back in the '50's ....

Ah yes; the good old days. We did it different then and we were still able to bag some meat. It wasn't wise; but it was still fun.
But I do it differently today. Musta learned something along the trail.

 

[Mikecr]

I noticed most people say neck sizing helps extend your cartridge life over full resizing. Ok so neck size it is. But then I noticed some people neck size without pushing the shoulder back each time. They only bump the shoulder every 3rd time or so. I've heard this called "bump sizing".

Much of our approach is/should be dependent on particular cartridge design, chamber dimensions, load pressures.
And there is logic that can be applied to each separate sizing(body, shoulder, neck).

Your best die is always your chamber. It's your custom upsizing die.
Fire form new brass a few times in your chamber with no more than partial neck sizing for bullet grip, and then measure it. Here you'll see your brass at it's most consistent point.
FL sizing will never get it there.
In fact, if you continue firing that brass with a regime of FL sizing at each reload, and carefully measure along the way, you'll see the brass forever changing as you go. Dimensions will change, runout will grow, capacity will grow.
Ultimately, the change is brushed off your bench -as trimmed away.

Where did the brass trimmed away come from?
It was squeezed up the cases from first contact of a FL die(near webs), thick towards thin. Like a tube of toothpaste. The brass rolls up into shoulders, neck-shoulder junction(donut), and necks, all the way to mouths.
Die sellers imply brass 'flow' which must be dealt with. This as though firing causes brass to move. No, truth is, we move it. Firing changes dimensions outward(never inward) and while this leaves brass thinning, it does not move thickness. It's sizing that creates the very problems that must be dealt with. The greater your sizing(anywhere) the worse things get.
This is why folks break sizing into separate efforts, custom, etc.

Why over-bump to get enough body sizing? Why would anyone FL size necks, with nothing good in that? We don't have to. We have plenty of choices to do anything we want.
I bump shoulders with no body sizing at all. I partial NS as a separate action, and mandrel expand necks separately before seating bullets. My trimming ended way back at initial preps.

 

[Canadian Bushman]

Mike what kind of consistency do you see when bumping shoulders only?

Can you get under .001 across the batch?

 

[Bart B]

. . . .if you continue firing that brass with a regime of FL sizing at each reload, and carefully measure along the way, you'll see the brass forever changing as you go. Dimensions will change, runout will grow, capacity will grow.

Ultimately, the change is brushed off your bench -as trimmed away.

Why would anyone FL size necks, with nothing good in that?

There's a lot of folks who do all that getting dozens of reloads per case shooting bullets as accurate as anyone along with getting resized case necks straightest on case bodies to do it. And their runout stays at the same small amount for all reloads on a given case.

Perhaps their tool selection and use is all the right stuff to begin with. And they don't care if the brass changes. It has to keep up with the way the barrel changes over it life; right?

 

[bigedp51]

Hello

I'm a newbie reloader so I've been trying to read and consume as much information as possible. I'm a bit confused on this topic however.

I noticed most people say neck sizing helps extend your cartridge life over full resizing. Ok so neck size it is. But then I noticed some people neck size without pushing the shoulder back each time. They only bump the shoulder every 3rd time or so. I've heard this called "bump sizing".

Any opinions on this?

Thanks
Sam

How about a answer from someone who shoots for "Team Lapua USA" and also worked in the Sierra ballistics test lab.

"Your cartridge should fit the chamber like a rat turd in a violin case"