Dies for Bumping Shoulder

My introduction to partial sizing came many years ago with a 7mm mag. Found out it had what they called a sloppy chamber And by 5 shot's was getting case head separations. To fix the problem I partial sized sized the case's and when done the case fit the chamber much better. I understand a lot of belted magnums are that way. They headspace on a belt rather than the shoulder. If the chamber is sloppy your gonna get head separations. Moved to cartridge headspacing on the shoulder and the problem goes away.
 
And this post doesn't cause confusion saying the same as mine using different word sequences?
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It takes head space out of the discussion (which we are not really talking about anyway_) and tell you what you want to do, simply move the should back .003 or .004.

Each to his or their own, its an alternative approach and I think simpler.

More accurate as head space is actually the distance from the face of the bolt to the datum point on the shoulder (and the relaxed case is not that let alone one with a bumped shoulder)

Head space is for setting a barrel on a gun. The case aspect revolves around tthat planet quite loosely in technical terms .
 
What's headspace on a rimless bottleneck chamber gauge?

What's wrong with measuring the case the same way for a comparison?

Especially when there's a few to several thousandths spread in tolerances for cases and chanbers.
 
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Some of ya’ll can make a simple thing difficult. Over the decades, I’ve full length sized, neck sized, partial resized, and used FL Bushing dies. These days I do a Partial FL Resize, which varies with rifles I load for. My 220 requires me to FL size as much as the die allows, due to a snug chamber. But if you have what we can call a “loose chamber”, a max FL resize might overdo it and eventually lead to case head separations. You size the brass too much (too small, for lack of a better term) and overwork the brass. My 223 is like that. The answer is to simply resize the case ‘enough’ and not overmuch. That’s what I now do. It gives consistent case sizes and no head separations. You can determine how much sizing is just right by trial and error, or Unclenick can tell you how to do it more scientifically.

Note that I didn’t describe it a bumping the shoulder. All you are doing is resetting the shoulder very slightly.
 
Thanks guys for everyone's input... has been helpful. I can't add any type of response as mentioned have no idea on this matter. Don't want to make myself look dumb with a comment, lol. Do have questions, but many have responded without me asking so far.

Ernie, thanks for both videos.

Bart, another member also mentioned about the Redding competition shellholders.
 
Don Fisher and 603 Country...If I understand you right I think you are partly right,with room to improve.

Don,I've owned and loaded for 3 7mm Rem Mags of my own..I understand and agree with the belted magnum case life issue you describe. I just don't 100 % agree with your solution. Belt headspacing was not designed around reloading.

It was designed around dangerous game. Its toleranced for reliability,once.

No one cares (but you) if yo only get 3 reloads. Because the belt is the designed headspace surface,additional clearance is designed in at the shoulder,and in the dies to be sure the belt remains the dominant factor in headspacing.
Its perfectly wonderful to choose to headspace on the shoulder! No problem! I do that myself!! We agree!!.

But here is a good,controlled way to do that. SAAMI won't help you,but you can use a "datum"ring bushing on the shoulder and a calipers to gain a comparative measurement of the fireformed case Yes? If you can do it for a 308,you can do it for a 7mm Rem.

Now,by the use of a feeler gauge or RCBS shell holders or trial and error or some secret salamander lips method,,you do NOT have to back the die off to partial resize,poke and hope,and let your shoulders be uncontrolled.
Why do that?

With some measurements and care,you can adjust your full length belted magnum resize die to full length resize,ignore the belt,and control the shoulder with the shoulder inside the sizing die to give you a known,controlled,repeatable .002 or whatever head clearance you want.

No problem.

We try to pass it on,no charge,you can do it too!

And we get the comeback " We been doing it this way and y'all are complicating it ….etc.

Thing is,I know exactly what I'm doing and the how and why.

Its really simple and easy. I'm just not worried about overcoming the resistance. I don't care if I convert you or not.

But I'll teach you for free.If you want.
 
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I don’t reload belted cases, but you and I still appear to be doing the resize the same way. Your use of a “datum ring” is the more scientific and more accurate way to do it.

However, your statement that a fellow never has to back off the FL sizing die is not correct. It will depend on the size of the rifle chamber versus the resizing die. Maybe you just haven’t run into the problem yet.
 
With proper resizing, 20+ reloads per belted case is possible.

Belted cases originated at H & H to prevent rimless bottleneck cases with an 8 degree shoulder from shoulder setback from firing pin impact and feed reliable from box magazines. Original case was rimmed for double rifles then modified for bolt action rifles.
 
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Belt headspacing was not designed around reloading.
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Reality is the only system designed around reloading was a muzzle loader!

Cases if they do the job reliably once are the real mgf goal.

We luck out tht to meet that they do far better if we take care of them.

Rimmed cases are another case shoulder control (as we are not setting head-space we are jus making sure the case is loose enough to function which can mean +.003 or negative (-) .015)
 
Belt headspacing was not designed around reloading.

It was designed around dangerous game. Its toleranced for reliability,once.
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This is a yes and no thing. There are few, if any rounds designed around reloading.

The first belted cartridge was introduced in 1912, the .375 H&H Magnum. H&H introduced the belted case and the term "Magnum" into firearms use at that time. This was done both as a marketing tool, and for a practical reason.

I don't know if it is accurate to say the belt was designed around dangerous game, but it was certainly first used there. The .375H&H does not have much of a shoulder. It was felt that the small shoulder of the .375 H&H case would not be enough for positive headspacing in "magazine rifles" (bolt actions) that were becoming popular at the time.

The belt allows for a positive "square shoulder" to headspace on, and avoids the issues of a rimmed case. It works tolerably well in both bolt actions and double rifles. Note that H&H also made the .375 Flanged Magnum, intended for use in double rifles, which had a case body identical to the belted magnum, but did not have a belt, it had a conventional rim, to be better suited to the double rifle extraction system.

The next belted round came in 1925, also from H&H, the .300 H&H Magnum. This case has a long sloping shoulder, again not well suited for headspacing.

For the next 30 some years, these were the only belted magnums, and the belt became firmly embedded in the buying public's mind as something "needed" for a magnum rifle case.

When Winchester created their line of magnums in the 50s and Remington did theirs in the 60s, "magnums" had belts, because that is what the public expected to see, and what they would buy. All those rounds were based on the original H&H case design, using the same head size and belt. Weatherby's Magnums began that way too, using "blown out" (less taper to the case bodies) H&H brass, necked to the bore size of interest (25, 27, .30,etc.)

Note that the later designed "ultra mags" and "short magnums" do not have belts. They feature very straight case bodies and large sharp shoulders which are easy to headspace on. Belts are not a necessity, they were something the buying public expected, at the time, and that's what they got.

As far as bumping the shoulder back a tiny bit, I understand the theoretical advantages, but not the practical ones, for me, or many shooters.

Certainly how much the brass gets worked during the firing and resizing cycle is a major factor in case life, but how much the shoulder gets moved during sizing is only ONE of the factors involved.
 
The reason competitive shooters full length sized belted cases bumping shoulders back a couple thousandths was to better center the case neck and bullet in the bore when fired. The belt never touched the chamber belt shoulder. Case shoulder centering in chamber shoulder was perfect when fired.
 
Certainly how much the brass gets worked during the firing and resizing cycle is a major factor in case life, but how much the shoulder gets moved during sizing is only ONE of the factors involved.
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I have to heartily disagree. The normal push of following the die mgs instruction is what causes the case to crack above the base in short order.

That vastly supersedes any other factors that may or may not come into play in 20 or 30 resizing.

If those other factors are there I suspect the noise level is so low as to be totally irrelevant.
 
Slightly off topic,but interesting.

Long ago ,maybe in "Rifle" or "Handloader" magazine,the topic of belts and the shallow shoulder angle came up.

I can't source this or back it up,but it seems like it could make sense.

A gentleman from England wrote in that Cordite was a factor.

According to his letter,they did not poke sticks of Cordite through the case neck in the loading process.The brass came as basic,cylindrical brass.

The charge of so many sticks of Cordite would be loaded in the primed basic brass,then the brass would be run through a case forming die to create the neck and shoulder. The shallow,gentle angles made case forming easier..But the shallow,gentle angles made for a lousy ,mushy,indefinite "anvil" to control for and aft location of the cartridge during ignition. The belt was a solution.

Its funny how a vestigial detail that is no longer relevant,like a belt,lingers on in tradition or market forces long after the initial reason ,(perhaps Cordite),has passed into history.
 
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Ah, Cordite. Amber strands, the length of the powder space. They did not use powder measures, but strand counts). I have a 303 somewhere and at one time had mil-surp 303 ammo, berdan primed. Might have been from India or Pakistan. I pulled a bullet and those strands could be coaxed out. It still shot.
Black powder (gunpowder is what UK called it) was replaced by Codite until WWII, when modern smokeless powders were invented. Both were used throughout WWII.
I believe one of the downfalls of Cordite was excess burn temp damaging MG barrels too quickly.
https://en.wikipedia.org/wiki/Cordite
 
I have to heartily disagree. The normal push of following the die mgs instruction is what causes the case to crack above the base in short order.
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How do you define "short order"??

I think the important factors are the pressure of the load and the relationship in the tolerances of the rifle chamber and the sizing die.

High pressure loads simply "work" the brass more. A chamber on the large end of the spec and a sizer die on the small end work the brass more. The brass itself (and its previous life) matters.

I've got some .308 Win cases that I first loaded in the early 70s, dozens of firing loading cycles full length sized and fired out of the same bolt action hunting rifle, every time. NONE has failed. I got others, mil surp stuff originally fired in MG chambers that hasn't lasted nearly as along.

Have also had a complete head separation with a "once fired" commercial .303 Brit case, on its first reloading. When loading .303 Brit nowdays, I don't set the die to do more than the neck, if the case fits the chamber, otherwise. They still don't last long.

I won't, and can't speak to the importance of doing certain things for match shooting, I shoot milsurps and regular sporting rifles which often don't show any advantage using advanced match loading techniques.
 
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However, your statement that a fellow never has to back off the FL sizing die is not correct. It will depend on the size of the rifle chamber versus the resizing die. Maybe you just haven’t run into the problem yet.
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I started handloading in the 1960's and barreling/chambering rifles in the 80's.

Fortunately,between my sense of workmanship and being taught properly,its true I have not run into many problems that were not easily solved.

Perhaps we only slightly misunderstand each other.

I assume maybe you have problems with your 220 Swift.Its a semi rimmed case,designed to headspace on the rim,with shallow shoulder angles and a tapered body. The Swift typically is being loaded with a 4000 fps + mindset.
My point is pressures are not likely to be mild.

It would not be unusual to have case life issues.

So far so good? We on the same page?

I can see no good reason to overly size the brass.I suspect your die is designed to get the case shoulder pushed down enough that the rim is fully responsible for headspacing. Often,the chamber is cut so that does not work out well. The solution,back the die off of the shellholder so the case headspaces on the shoulder. That's what I have done. I'm guessing we agree on that.

I'm thinking the only place we might be doing things differently is with "What is next?"

My understanding of "Partial sizing" is about backing the die off by "turns". One turn,or 1 1/2 turns,etc to just take the case body sizing out of the picture.
That's where we may part procedures. You might get away with using a Lee collet neck sizing die here,rather than backing your sizing die out to "partial size" I can't say for sure,I full length size.

But if I just wanted to headspace on the shoulder,without working the brass,I'd first measure the fireformed case,over the shoulder,by using a bushing. Just a ring to rest on the shoulder and give me something to measure. I'd screw my die down till I got a change of about .002 on my calipers after full length sizing.

Then,to make life easier,I'd try feeler gauges between the shellholder and the die to find one I could just put beteen the shellholder and die body,It might be the .008,I don't care.Whatever works. Next time,I screw the die down on the ,008 feeler gauge. So,yes,I would back the die off .008,but don't forget I sized that case for .002 setback,so my shoulder has been uniformy full length resized.

I use a gauge,not "Turns". Then I'd measure my results,because on tht day,with that brass,I might need a .010 feeler gauge or a .006.

And I am controlling .002 head clearance on a case shoulder that has been restored by the die to at least a degree.

In the handloading language I speak,that is still full length resizing.The shoulder gets sized,just far less. With the repeatable process,we have control,and can tune our outcome.

Calipers,a hardware store bushing,and some feeler gauges. It ain't a NASA project

And I'm happy to share . Good luck!
 
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We appear to be doing exactly the same thing. As you guessed, when I spoke of backing off the die a bit, I was not talking turns of the die but more (which varies) parts of a turn. Because many folks consider that a FL resizing mean having the base of the die forcefully contact the shellholder, I started using the term “Partial FL Resizing”. But...then some folks thought I was talking about Partial Resizing, which I did for years and which worked great with the 220 Swift. After Partial Resizing, I went to neck sizing, then to neck sizing with the Lee Collet Die, then on to “Partial FL Resizing”. The Lee die worked great, but sooner or later the brass grows and has to be FL resized. And after a long series of tests I did with the 223 and varied methods of resizing, I found that the PFLR approach seemed as accurate as using the Lee Collet Die.

As for the 220 Swift, I’ve had this rifle since about 1980. Brass was hard to get, so I bought Norma factory ammo and reused the brass. It was Norma brass, and from what I’ve read (and believe to be true) that is some particularly tough and thick brass. It was originally a military round - the 6mm Lee Navy. I reloaded that stuff way more than I probably should have, but since I was Partial Resizing, it lasted for many years and a crazy amount of reloads. And the 220 brass does flow with firing, so don’t listen to anyone that might say otherwise. But, I didn’t know that back then, so I resized and trimmed and resized and trimmed, on and on. The consensus is that doing what I did with shooting and reloading that brass, with the brass flowing, the necks would thicken. They did not thicken. The neck walls actually thinned.

Anyway, regarding case resizing, we appear to be saying about the same things.
 
How do you define "short order"??
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6 firing and 5 reloadings.

Go ahead and fire a case (lets use something common like 308/30-06/270) , measure the shoulder. Then do the die mfg contact the shell holder (assume no CoAx) and then turn the die in 1/4 turn.

Then measure the shoulder. Let me know what you get.
 
RC20, I assume your comment was for someone else,,but I'll give it a try.

Who knows what mix of manufacturing tolerances you will run into,but the general plan is ,if we do as you say,we should produce ammo at the minimum

range of SAAMI spec,so it will work well in the tightest of SAAMI chambers.

But that is just what is "supposed" to happen. What you get is the result you measure.

I can't tell you what that will be,and neither can anyone else.

The tools SHOULD produce ammo that will work in any SAMMI spec chamber.

That will mean in many rifles,it will result in more than necessary head clearance. Excessive head clearance results in shorter case life.

With simple skills and tools we can set our dies to minimize head clearance to one specific rifle. That should extend brass life.

It seems so incredibly simple to grasp.I don't understand why folks have such a hard time with it.

What is so hard?
 
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