How often do you bump the shoulder back?

[Barrelnut]

What about the aspect of a spring style ejector, in the bolt head, forcing that perfectly straight loose chambered cartridge sideways inside the chamber? My understanding is that some bench shooters remove the ejectors for this reacon. Seems it would certainly push a loose chartridge slightly sideways. Even one that is FL sized and just bumped .002.

Good input from the Lapua team guy. But he does say that they had to FL size because the test ammo had to fit in different chambers. He does not say that he would have not gotten 1/4 MOA groups, instead of 1/2 MOA groups, if just neck sizing was used. He is just saying that FL was accurate to less than 1/2 MOA. He is not really saying that neck sizing is not as accurate.

 

[tbrice23]

Anyone else think that the brass expands to fit the chamber as the gases from the powder ignites well before the bullet leaves the case neck????
At that moment everyone's cases fit the chamber perfectly.

 

[Barrelnut]

Anyone else think that the brass expands to fit the chamber as the gases from the powder ignites well before the bullet leaves the case neck????
At that moment everyone's cases fit the chamber perfectly.

I'm no expert, but yea, I like that thought. Seems it would be straightening the case from the web to the case neck as the pressure from the ignition spreads from the back to the front.

 

[bigedp51]

What about the aspect of a spring style ejector, in the bolt head, forcing that perfectly straight loose chambered cartridge sideways inside the chamber? My understanding is that some bench shooters remove the ejectors for this reacon. Seems it would certainly push a loose chartridge slightly sideways. Even one that is FL sized and just bumped .002.

Good input from the Lapua team guy. But he does say that they had to FL size because the test ammo had to fit in different chambers. He does not say that he would have not gotten 1/4 MOA groups, instead of 1/2 MOA groups, if just neck sizing was used. He is just saying that FL was accurate to less than 1/2 MOA. He is not really saying that neck sizing is not as accurate.

The ejector pushes the case forward in the chamber until the shoulder of the case contacts the shoulder of the chamber.

A full length resized case is supported in the rear by the bolt face, it is centered by its cone shaped shoulder contacting the cone shaped shoulder in the chamber and also centered by the bullet in the throat. The body and neck of the full length resized case does not touch the chamber walls. Meaning it fits the chamber like a rat turd in a violin case.
(but never sideways in the chamber)

Below is a "average" Remington .223 case and it has .004 neck "and" body thickness variations.

So who in their right mind would want to neck size this case with a bushing die? When a case like above is fired it warps and becomes banana shaped because the thin side of the case expands more when fired.

The average person with a off the shelf factory rifle with a standard SAAMI chamber is better off full length resizing his cases with minimum shoulder bump.

 

[Bart B]

Bottleneck cases headspacing on their shoulders of the right dimensions don't have their heads against the bolt face when fired. The firing pin drives them forward pushing their shoulder hard into the chamber shoulder (often setting that shoulder back a thousandth or more). There's a few thousandths clearance (head clearance in SAAMI glossary) between the bolt face and case head. That's needed on chambering the round so the bolt head goes into battery the same for all shots fired.

Extractors typically push the case back end against the chamber wall on chambered rounds. So the back end of the case is a thousandth or two off center in the chamber at that point. Not a problem.

When the round fires, the bullet's gone before the back half of the case expands against the chamber wall and its head against the bolt face. Greatly reduced loads have case headspace shorter after firing than before; proof the case body expands fully back only at close to normal peak pressure; but the bullet's gone proving low pressure loads don't push the case fully against the chamber limits. And their primers will be backed out a few thousandths because pressure wasn't enough to push the case head against the bolt face to push them back in from being pushed out a bit long before peak pressure is reached.

I've shot dozens of rounds with reduced loads down to 15% or more below max to observe this stuff.

Martin James (Jim) Hull, Sierra's first ballistic tech, was a good friend I shot many matches with. He may be the one most responsible for proving full length sized bottleneck cases fitting the chamber "like a t*rd in a punch bowl) [his other moniker] produced best accuracy back in the 1950's. Minimally sized so the fired case shoulder's bumped back a couple thousandths is all that''s needed for long case life and best overall accuracy. When Sierra finally made their first hollow point 30 caliber match bullet (The 168-gr. International), he was finally able to get 1/10th inch 10-shot groups frequently in their 100-yard indoor test range with any bullet larger than 24 caliber. No other fired case resizing tool or technique did that but the Lyman or RCBS standard full length sizing dies with their necks honed out to a couple thousandths smaller than a loaded round neck diameter. Sierra's tool and die shop modified their dies to do that. About 10 years ago, the benchrest folks finally started doing the same thing with dies custom made to size bodies down only .001" instead of a bit more that standard dies do; I've no idea why they took so long to do that.

 

[bigedp51]

Bottleneck cases headspacing on their shoulders of the right dimensions don't have their heads against the bolt face when fired. The firing pin drives them forward pushing their shoulder hard into the chamber shoulder (often setting that shoulder back a thousandth or more). There's a few thousandths clearance (head clearance in SAAMI glossary) between the bolt face and case head. That's needed on chambering the round so the bolt head goes into battery the same for all shots fired.

Bart B

The $64,000 question, what pushes the cartridge case forward into the chamber until it contacts the shoulder of the chamber??

Or are all your rifles old Mausers, Mosins and British Enfields?

Bazinga!

 

[Mikecr]

Mike what kind of consistency do you see when bumping shoulders only?
Can you get under .001 across the batch?

Not sure where the 1thou question applies. Do you mean in shoulder datum?

I can and do make perfect as practical ammo. It's one thing I just do.
My bullets are seated to desired CBTO with well under .5thou total variance.
Cases with my fitted 6.5wssm have never been sized other than shoulder bumping, and have ~40 reloads now. No re-trimming, annealing, no body or neck sizing at all. Runout still below measure(<.0005 TIR, surface profile interferes with lower measure than this). Next barrel chamber gets 45deg+ shoulders to end shoulder bumping as well.
H20 capacities still matching.

It's evident to me that I will not ever 'eventually have a problem' with this. So fitted is the way I'm going with all future cartridges. I don't care about factory labs shooting rat turds for ammo. I'm confident I have my guns shooting as well as anyone could make them shoot.

To the fellow who thinks crooked ammo is self centered by bullet release; The necks are first to expand the roughly .000000000000000000001" needed to freely release a bullet. Every other dimension afterwards means nothing to results -other than reloading. This is why runout means little while clearances are high. Tighten chamber clearances, and runout begins to matter.
Crooked ammo bound in a chamber(chamber tensions) can mess up results. These are pressure points similar to laying your thumb on the action tang during firing(don't take much). So of course you want these tensions consistent.

I suspect this is why folks see improved results with FL sizing. If I measured their ammo on a v-block I'd see ugly runout beyond what I'm used to. Most are probably shooting poorly designed rat turds as well, so they're candidates for 'eventual problems' in neck sizing only.

 

[Canadian Bushman]

Not sure where the 1thou question applies. Do you mean in shoulder datum?

Yes that is what i meant.
I always run around .002", maybe more some days and lately have wondered if the die was only contacting the shoulder it would bumb the shoulders more consistently.

 

[Mikecr]

I bump 1thou. Not 1.25thou, not .75thou.
I chose 1thou simply because all my other clearances are 1thou also.
This takes effort to pull off, especially with hard brass, and forget precision here with low shoulder angles and high body tapers.

You must have body-shoulder support for accurate bumping. Support is squeezing at least.
I use custom JLC/Redding body dies for bumping.
It takes a thin lube for adjustment, while verifying every bump with a good tool(a 'gizzy').
RCBS case lube wiped on with fingers works really well to dial in perfect bump, case to case.
I prefer this over constant die/holder adjustments.

 

[Bart B]

The $64,000 question, what pushes the cartridge case forward into the chamber until it contacts the shoulder of the chamber??

Get your checkbook out along with a pen to fill it out then send it to me.

Or are all your rifles old Mausers, Mosins and British Enfields?

No, controlled and push feed Winchester 70's and a push feed Paramount. The ejectors have been removed from the push feed ones so cases will stay in the action until I pull them out to put back in the ammo box; keeps them from getting dirty on the ground during a match.

Regarding this image:

Having used layout dye on .308 Win and 30 caliber magnum case shoulders (on cases headspacing on their shoulders) to see how the chamber shoulder fingerprint gets stamped in them, here's what I've observed.

When a controlled feed bolt's closed chambering a round from an internal box magazine, the case shoulder shows little or no fingerprint from the chamber after extracting that round from the rifle

After chambering a round (with primer but no powder or bullet) in a controlled feed action loaded from the magazine, then firing it, the firing pin drives the case shoulder very hard into the chamber shoulder. That leaves a pronounced chamber shoulder finger print on the case shoulder. And it often sets the case shoulder back; Hatcher observed .30-06 cases in Garands and machine guns having their shoulders set back .004" to .007".

If I push a round part way into a controlled feed action then into the chamber, closing the bolt on it has the extractor lip first contacting the case rim and pushing it hard enough into the chamber that it stops against the chamber shoulder before the extractor lip slips over the rim and into the case extractor groove; easily seen by extracting the unfired case and seeing the fingerprint on its shoulder. If a case so chamber is fired, the firing pin impact does the same thing as above.

Chambering a primed but empty case with a push feed action with a spring loaded in-line ejector (like the one in the picture) loaded from the magazine or partially inserted directly into the chamber will have either the bolt face shroud, ejector or extractor claw first push the case shoulder against the chamber shoulder; depending on which one is furthest forward on the bolt head. But the finger print on the case shoulder is still minimal.

In all chambering and firing situations, only when the firing pin smacks the primer is the case shoulder driven hardest into and against the chamber shoulder which is what I referred to. Extractor's and ejector's force on the chambered case is small compared to that of the firing pin driven by a 26-pound spring impacting primers at 6 MPH. The extractor often pushes the case back end against the chamber at its pressure ring if the bolt face shroud's large enough to allow it

In all my rifles, as well as what's typical of all others, there's enough clearance between the bolt face and extractor claw to let the case rim be driven full forward until the case stops against its headspace limit before the case rim stops against the ejector claw.

Bazinga! back to you. Once for each situation I explained.

Make that check out for only two cents; that's all my comments are worth. This whole thing is too simple to figure out once one know exactly how cartridges fit and move in chambers from external forces to be worth any more. If it was really complex, then it would be worth more.

 

[BountyHunter]

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.

You and I have had this conversation before.

1. You use custom honed JLC body dies that have .001 body sizing. Jim has said that he does not hone any smaller.

2. You load the WSSM 10% below SAAMI, otherwise you have posted that you have to FL size every time.

3. **** few LR hunters load 10% below SAAMI so your technique of NS only is totally irrelevant and will not work for most LR hunters.

4. Sharp shoulders like the WSM and WSSM are not going to flow much at all if any with FL sizing, so basing your advise off that case is red herring. Try that crap with a 30-06 or anything less than 35%.

5. 90% of the top LR competitors are FL sizing every time with dies that are fitted closer than just off the shelf. IF it was not accurate and reliable they would not do it.

If someone has to ask the question as to what to do, do not give them advice that is based off one set of very limited parameters on the case and load. You are doing that person a disservice with faulty information for his needs.

 

[Mikecr]

You and I have had this conversation before.

We have had to conversation before & you still don't listen to the answers.

1. You use custom honed JLC body dies that have .001 body sizing. Jim has said that he does not hone any smaller.

Jim makes dies based off fired brass we send him. We don't send our chambers. I send him over-pressure brass that predictably leads to custom body dies that squeeze without sizing. Write that down, think about it, and try to remember it.

2. You load the WSSM 10% below SAAMI

My accuracy load is 47.4gr IMR4350 behind 139Laps 8thou off. The H20 capacity of my 6.5wssm matches that of the 260AI, and my muzzle velocity is ~3025fps w/28" barrel. QuickLoad put's this right at SAAMI max(65Kpsi). Anyone w/QL here can run that & see for themselves.
SAAMI max is different than MyMax. I can run higher pressures, and the brass I sent to JLC provided MVs over 3200fps. By that point, body sizing would be required.
I have noticed that ~57Kpsi by QL seems a rough reference for sizing requirements with less improved cartridges. And I realize I once reported a bit less predicted pressure with my 6.5wssm(by mistake). But I'm pretty confident in numbers I've posted many times since. 57Kpsi is not 10% below SAAMI max with hunting capacity cartridges. It's plenty, and max loads in your books are below this.

otherwise you have posted that you have to FL size every time.

Where the hell are you getting this? I don't FL size anything.
The last time I FL sized was in a reloading class ~40yrs ago.
Since then I partial NS'd with FL dies, until bushing dies hit the scene.
Do YOU even know what FL sizing is?

If someone has to ask the question as to what to do, do not give them advice that is based off one set of very limited parameters on the case and load. You are doing that person a disservice with faulty information for his needs.

I provide info in contrast to so much posted with no basis at all(like all LR shooters do it).
I built that 6.5wssm as fitted purely for this testing. To find some truths behind a different reference than gun rags puke out..
It's true a 30-06 will have to be FL sized. It's a horrible design. And I don't see any in IBS equipment lists. So folks, don't even bother with NS only for anything over 100yrs old.
But with a newer cartridge, like a ~6.5x47L, a fitted chamber and rational loads behind 130gr bullets, you could partial NS and shoulder bump only. Go ahead, just for the learning, and nothing to lose.
Then, when you read that a LR competitor says that FL sizing is a must, you can decide if that's actually true, unqualified, or merely another trend roundy roundy.

 

[BountyHunter]

Mikecr

Here are your quotes and they are all over the map.

1-28-13

You make good points that most of my loads are lower in pressure than SAAMI max, and that my cartridges are relatively smaller than many hunting cartridges.

Again, what relevance is that type cartridge to the type cartidges and pressures ran by LR hunter. A: ZERO

Totally different game is the reason.

Now if I went with a faster load/powder(H4350), higher pressures, I could reach a node that would flat out pass most 6.5x284s. It might also shoot as well faster I don't know. But with this, I would have to FL size, and my cases would no longer be matching, and my primer pockets would open before long.
Doesn't make sense to do this. Not with a milder 3020fps node at hand.

I went with a magnum diameter BAT action to get enough barrel steel around the chamber.

10-13-14

I have observed with several cartridges that 57Kpsi seems the point where FL sizing is required. I've run several to that point(as measured at webline) and noted that QL showed this pressure. You're right that QL is not always right, it's not a direct measure. So I'll concede that QL pressure may or may not be accurate with my 26wssm load. But the velocity does match for that measured H20 capacity, seating, and powder. I'm pushing 139laps at 3020fps with 260AI capacity, so it's not a light load for sure. I have taken it to 3200+, and there is a node up there, but it isn't worth it. This would required FL sizing.

Pretty sure I've implied that MY MAX is typically ~55-57Kpsi.
You've countered before that these are unrealistically low pressures for performance.
Is that half the story?

6.5WSSM imp, 139LAP, 28"barrel, 3050fps, ~57Kpsi QL, 47.4-IMR4350
Fitted cartridge, shoulder bumps only on 30+ reloads, Zero body sizing so far, no trimming, no annealing.

this post

My accuracy load is 47.4gr IMR4350 behind 139Laps 8thou off. The H20 capacity of my 6.5wssm matches that of the 260AI, and my muzzle velocity is ~3025fps w/28" barrel. QuickLoad put's this right at SAAMI max(65Kpsi). Anyone w/QL here can run that & see for themselves.

So same load has suddenly gone up 8KPSI when someone throws the BS flag? Well either you or QL is full of it. Which is it?


I shoot the 6.5x47 LR and until recently much larger cartridges in competition and won a lot. We (winning competitors) talked all the time about what we were doing and why, so I am not reading it anywhere, yes it is true that FL sizing is the way to go and not a trendy roundy as you imply. It is correctly done with a FL bushing die (normally) that that is fitted to the chamber and gives minimal enough but minimal sizing at the correct spots. You have had this conversation with Matt (duckhunt14) who is a record holder at 1k and he has explained it in detail also, but you are just hung on NS only with small cartridges and somehow think it applies across the board.

More importantly, lets put this in the proper perspective You built an undersize case (for LR hunting) in an oversize action, loaded at 57K which is more than 10% below SAAMMI, and not to max potential and think that somehow relates to larger magnum cases in LR hunting? Plus your answer to the everyone regardless of experience, is to follow that advice without laying out all the caveats?

You puked out your standard NS only answer as the way to go and did not even notice that the OP did not list what cartridge they were reloading for. It could have been the 30-06. NO just puke out the NS only crap as the only answer no matter what. That makes your advice total BS to the novice! Somehow you do not see that as a disservice to them?

 

[Bart B]

The necks are first to expand the roughly .000000000000000000001" needed to freely release a bullet.

I don't think case necks expand at all to let bullets out. And necks will only expand at points behind the bullet; there's no outward pressure on the case around the bullet; if there was, a lot of gas cutting blow-by would happen.

A 26 caliber bullet that needs 10 pounds of force to push it out of the neck will go out with pressure at 183 psi in the case. I don't think ts neck needs to expand at all with zero clearance to the bullet. Gauge blocks with zero clearance between their flats can be wrung apart with little force.

I suspect this is why folks see improved results with FL sizing. If I measured their ammo on a v-block I'd see ugly runout beyond what I'm used to.

A couple thousandths of ugly runout on .308 Win ammo shot in a SAAMI spec chamber has put 40 bullets inside 2 inches at 600 yards. Had they all been at zero runout, then perhaps the group would have measured zero. Therefore the formula for runout must be 1/6 MOA group enlargement for every .001" of runout. Right?