Shoulder Bump Die?

[bigedp51]

I have a Forster bump bushing neck die and without the bushing in place you can just bump the shoulder back. "BUT" I prefer full length resizing and the rat turd in the violin case method.

On my .303 British cases I bump the shoulder back just using a .303 case forming and trim die.

There is quite a bit of speculation and guesswork (WAG) going on here, and when my cases are longer after doing this I know which way the brass flows.

My 2 cents

 

[Barlow]

Just curious, why don't you just full length resize? Barlow

 

[Brians356]

Just curious, why don't you just full length resize? Barlow

What would the Redding Body Die I said I ordered do if not full-length resize (assuming you are referring to the body, not the neck)?

 

[fguffey]

Quote from: brians356 on Today at 11:51 AM

how can the shoulder be set back when there is no place for the brass to go?


It goes inward, usually thick toward thin. Given that cases taper in thickness from webs all the way to mouths, brass thickness rolls upward to donut & eventually trimmed away(with heavy FL sizing). Not so much with a thou(after springback) of shoulder only bumping.

"It goes inward, usually thick toward thin" Brass does not go inward, without case body support the case collapse like an according, it forms bellows. Then there is that shoulder bump thing again. I can not bump a shoulder, where I size a case the case body is supported when the shoulder of the die contacts the shoulder of the case, meaning if there is such a thing as bump I bump the case body and shoulder at the same time.

Sizing the shoulder and case body without sizing the neck: I have been doing it for years, long before they started making dies they call bump dies.

brass thickness rolls upward to donut & eventually

Brass rolls like a wave?

F. Guffey

 

[Brians356]

Update:

I set up the Redding Body Die using the Redding Competition Sehllholder set. Using the +.008 shellholder and a 1/8 die turn cam-over in the press, the cases now chamber with significantly less resistance - but not like unfired cases.

Using a .375-cal Stoney Point bullet comparator to contact the shoulders near the middle, my low-tech Mitutoyo dial caliper indicates the shoulders are being set back ~1-2 thousandths. Using a good micrometer, I cannot detect any case diameter reduction at the pressure rings.

My conclusion is that, using the controlled sizing afforded by the stepped shellholders, the "body die" has been used successfully as a "bump die".

 

[fguffey]

Fantastic, simply fantastic, how do you do it. I know, everyone understands,

I can not do that, my die contacts the body of the case first, then the shoulder of the die contacts the shoulder of the case. Then there is the Redding +.008: shell holder with the added .008" deck height, I increase the gap between the bottom of the die and top of the shell holder .008" with a feeler gage, same thing, expect I do not find it necessary to screw the die down an additional 1/4 turn, I do not find it necessary to punish the press

Before drawing a conclusion I suggest you measure the diameter of the die opening. Not for everyone, I have no problem turning a case around and placing the case into the die with the big end in first. With few exceptions the case head is smaller in diameter than the diameter of the die at the opening.

The shell holder has a deck height, the deck height of a shell holder is .125", you are using a shell holder that has a deck height of .133", added to that number is the case head protrusion and unsupported case head. To complicate those numbers is case head thickness from the top of the cup to the case head, I have case heads with a thickness of .260", when drawing conclusions I have to consider case head upset meaning the die is not going to size the case head unless it contacts the die.

Contacts the die: I have dies that have a very reputable name stamped on them, they are different, the opening of the die is .005" smaller in diameter than the diameter of all other dies made for different years. I could send the die back for warranty, the question would be 'why? The die is smaller in diameter at the opening than a small base die. I do not have a case from the 30/06 family of cases that can be turned around and placed into that die case head first.

F. Guffey

 

[bigedp51]

brians356

A Redding body die is a full length resizing die that doesn't size the neck.

If you look at my .223/5.56 dies below you will even see a small base body die.

Save yourself some headaches and get a full length resizing die, a Hornady cartridge case headspae gauge and a runout gauge.

A full length resized case is supported by the bolt face in the rear of the cartridge case.

The bullet in the chamber throat is supporting the front of the case.

A full length resized cartridge case doesn't have the body of the case or the neck touching the chamber walls. This greatly lessens any influence case misalignment might have from imperfectly made cartridge cases and centering the bullet with the bore.

It will also keep you from reading postings where the poster quotes himself in a shoulder bump posting and has you putting case in your dies bassackwards.

 

[Brians356]

brians356

A Redding body die is a full length resizing die that doesn't size the neck.

Uh, ... yeah. I don't believe I have said or implied otherwise - have I? ???

Save yourself some headaches and get a full length resizing die,

Why would I do that? You just told me I already have one. And I don't want to size the neck with the same die. So my Body Die is, as you point out, actually a full-length sizing die for purposes of sizing the body. Between my Body Die and my neck-sizing die, I have all sizing covered - including, as I just proved, bumping the shoulder without resizing the base of the body (unless my micrometer lies.)

A full length resized cartridge case doesn't have the body of the case or the neck touching the chamber walls.

That's dubious. I doubt the boltface is necessarily in perfect enough concentricity with the chamber to suspend the case with nothing but air all around it in the chamber. And I doubt it matters either way, so I'll concede the point.

Once a case is fireformed to the chamber (presumably while being properly aligned as you yourself say it will be!) it will darn well be properly aligned in that chamber upon subsequent firings and forever more, without being resized.

I want to avoid overworking my brass. Therefore I choose not to resize the bodies - except when a too-hot load produces a tight extraction / chambering issue, whence I can bump the shoulder back slightly, without reducing the body, using the die and technique I demonstrated this morning. And I use a bushing die for the necks, squeezing them down only 1 or 2 thousandths under bullet diameter.

FWIW there is a body of conventional wisdom saying that brass handled this way often produces loads accurate enough for demanding varminting at least - which is my application (I don't own any competition rifles.) I have printed more than a few one-ragged-hole five-shot groups at 200 yards off the bench using my approach, and generally can keep groups well under 1/2 MOA, closer to 1/4 MOA, using only mass-produced rifles (I admit: bedded, floated, and trigger-tuned) such as R-700 and Sako Vixen.

I'm not saying you're not onto something simply marvelous, I'm just saying I'm not experiencing any headaches, but thanks just the same.

 

[bigedp51]

Once a case is fireformed to the chamber (presumably while being properly aligned as you yourself say it will be!) it will darn well be properly aligned in that chamber upon subsequent firings and forever more, without being resized.

We don't live in a perfect world where every cartridge case is perfectly made.

So I have three "marvelous" examples for you to look at and understand that fireforming the case doesn't mean its perfectly aligned with the bore.

The Rifleman's Journal
by Germán A. Salazar

"Thanks for writing! Your question is a good one. You're correct that the Type S die can be adjusted to provide partial neck sizing. Unlike the competition neck die which has a spring-loaded collar, the Type S will just let the bushing ride the case mouth up until the top of the bushing stops and then it will size to whatever degree is left.

The real question is whether using the unsized portion of the neck to center the cartridge in the chamber is practical. I think this is not an optimal solution for a few reasons. First, let's consider what we're really after - we want the bullet to get a good, well-centered start in the rifling. Now let's look at a few scenarios to get there.

A case that is only neck sized depends on the case body itself - or at least that's the theory - to center the bullet. In reality, the case is banana shaped to a greater or lesser degree, but always curved and it is highly unlikely that it will actually put the bullet into perfect, straight alignment in the throat. The fully resized neck and a bit of clearance in the throat mean that the bullet is likely pointed off center to some degree, following the curvature of the case.

A case that is full-length sized, but only partially neck sized, which is the condition you describe, depends on the unsized portion of the neck to center the bullet. The resized case body is still banana shaped, but has been sufficiently reduced in diameter at the shoulder to keep the curvature from wedging the case within the chamber. Now, we get to the unsized portion of the neck. There is approximately 0.001" diametrical clearance to the chamber neck on the unsized portion just from normal brass springiness. There is probably no more than 0.0005" diametrical clearance between the bullet and the throat and in many cases as little as 0.0002" clearance. In other words, there is one-half to one-fifth the clearance in the throat that there is in the unsized portion of the neck. Which is doing the alignment? If that were all, we could say there's no harm done by the partial neck sizing, but that isn't the whole story. Unless the bullet is perfectly concentric to the neck, there exists the possibility that the bullet's alignment in the throat is being influenced by the neck's eccentricity in relation to the bullet. If you're relying on two points to align the whole, those two points had better be perfectly concentric. The longer the unsized portion of the neck is, the greater likelihood of the neck inducing a misalignment in the throat due to imperfect neck to bullet concentricity.

Now the last scenario, a full-length sized case in which the neck is also fully sized. There is clearance at the neck and in the body of the case, the closest fit anywhere is the bullet in the throat. If the neck to bullet concentricity is good (although it needn't be perfect), then the bullet will find good alignment in the throat and the case body and neck will have minimal influence. Let's not forget that the base of the case is supported by the bolt face or the extractor to a certain degree as well; this is yet another influence on alignment. As you can see, there are several points from base to bullet that can have an effect. My procedure is to minimize the influence of those that I can control, namely the case body and neck, and let the alignment be dictated by the fit of the bullet in the throat and to some extent by the bolt's support of the base. Barring a seriously out of square case head, I don't think the bolt can have a negative effect on alignment, only a slightly positive effect from minimizing "case droop" in the chamber. Given that a resized case will usually have a maximum of 0.001" diametrical clearance at the web, this isn't much of a factor anyway.

In conclusion, I believe that allowing the bullet to find a relatively stress-free alignment in the throat by full length sizing (including the neck) and turning necks to enhance concentricity gives the bullet the best probability of a well-aligned start into the rifling. Additionally, I place a high value on easy bolt operation and true full length sizing helps that quite a bit. I favor easy bolt operation as a prone shooter because I keep the rifle in my shoulder for the entire string and struggling with the bolt not only can shift the buttplate (always with adverse consequences) but it is also a distraction from my attention to mirage and wind flags which ideally occupies all of the non-aiming time."

Germán

http://riflemansjournal.blogspot.com/2010/06/reloading-partial-neck-sizing.html


If you haven't guessed I belong to the rat turd in the violin case club.

 

[Old Navy]

I love this topic. Later! Frank

 

[Brians356]

bigedp51,

Thanks for all that reference material! You're very generous, and your cut/paste skills are unsurpassed. If ever I have trouble creating accurate loads, it will be comforting to know I can revisit this thread to find these secrets.

 

[BoydAllen]

Let me tell you a story that relates to dies and shoulder bumping. A friend built a .243 AI but did not want to invest an expensive die for sizing. Since he had a .243 Collet die that would size the neck, he was good to go for a couple of firings, then things got a little tight, so he made (from scratch) a bump die using his chamber reamer. That worked (case supported, and shoulder successfully bumped) but as I told him it would, he ran into bolt close issues because of expansion at the back of the case, and came to me looking for advice. I looked around and found an old non carbide RCBS ..45 ACP die set at a gun show, bought it for $10 (He had done me some favors, so I donated it to the cause.) and gave the stripped sizer die body to him with the instructions that it might make a ring die for his cases' bases, but that he might have to polish it out a bit on his lathe. He did, and it worked as planned, so now he can size cases every where needed for a good bolt close. Now if it was me, I would have bought a FL die, managed to come up with some old, work hardened fired cases, sized them, measured them, and ordered a chambering reamer that would give me the clearances that I wanted, but that is just me. In any case, his problem was solved, and the rifle is very accurate.

 

[mikecr]

Brians356, you got a great handle on this and sizing in general.
Glad the body die fit so well, sometimes they do and hopefully it will continue.
Now if you don't have it yet I suggest Sinclair expander die/mandrel for pre expansion prior to bullet seating. Make straighter seating and more consistent depths/tension.

 

[bigedp51]

bigedp51,

Thanks for all that reference material! You're very generous, and your cut/paste skills are unsurpassed. If ever I have trouble creating accurate loads, it will be comforting to know I can revisit this thread to find these secrets.

brians356

You are very welcome and I really appreciate your sincerity, I also build computers as a hobby so any time you feel like it you can byte me.

What really puzzles me is if you know so much why did you post and ask your question in the first place.

I am looking for a shoulder-only "bump" die, thought Redding made them, but all I find are "body" dies which full-length resize the body.

I prefer not to resize the base, only bump the shoulder back a tad. Who makes what I want? (It's for 6mm Rem.)

If you forgot my cut and paste answer it was my Forster die below.

 

[bigedp51]

brians356

I also posted that you can use a case forming and trim die as a shoulder bump die, and not alter the case body dimentions as much as you did with a FULL LENGTH resizing body die raised .008

"Redding Trim Dies allow you to file trim your cases without unnecessary resizing because they are made to chamber dimensions. Other manufacturers use sizing die dimensions, forcing you to full length resize when trimming. For case forming and necking brass down from another caliber, Redding Trim Dies can be the perfect intermediate step before full length resizing."

The fired case below is being held in place with my little finger to keep it from falling out of the die but also works "marvelous" for only bumping the shoulder of the case.

Redding Trim Die 6mm Remington
http://www.midwayusa.com/product/508842/redding-trim-die-6mm-remington?cm_vc=ProductFinding

The above message was brought to you by the "Cut and Paste" society of America and Masters of Bumpology.

 

[BoydAllen]

I am always glad to learn something new. I'll file that one away.

 

[LHSmith]

Someone has to explain how a thicker (Redding Competition S/H - in this case + .008") solved his sizing problem......they go the wrong way.....they need to be shorter than the nominal .125"....or material must be removed from the bottom of the die. ???

 

[bigedp51]

I am always glad to learn something new. I'll file that one away.

BoydAllen

A person with the initials "fguffey' said here you can't bump the shoulder back if the case is not supported, and yet I have two dies that support the shoulder and allow you to only "bump" the shoulder back. Therefore some posters are making "unsupported" statements. :

All people need to know is that we live in a plus and minus manufacturing world and what happens between the blue, red and green dotted lines below.

They also need to learn that a full length or body die is not a bump die no matter how much space is between the shell holder and the bottom of the die.

This isn't rocket science but some YoYo's need to learn the difference.

And more people need to READ the front part of their reloading manuals and the "marvelous" information other people have already learned.

Signed
Sincerely, Mr. Cut and Paste.

 

[bigedp51]

Someone has to explain how a thicker (Redding Competition S/H - in this case + .008") solved his sizing problem......they go the wrong way.....they need to be shorter than the nominal .125"....or material must be removed from the bottom of the die. ???

Not if he has a Savage rifle and put on a new barrel by himself and used scotch tape on the back of a case to set his headspace.

This is where our plus and minus manufacturing world collides with "marvelous" ideas. :

Please understand I'm sorry, (sometimes) you see I'm retired and this is the only excitement I get every day. Just remember you can always lean on Boyd Allen for sanity when you really need it in this forum.

And some people need to read more books other than on reloading......................................

 

[lrgoodger]

Very interesting and timely thread. My pile of 1000 6BR casings have been neck sized only 5 - 7 firings and I am in the process of figuring out how to full size them without destroying neck concentricity. The Forster bushing bump die did not do it (without the neck bushing, of course). No matter how carefully I set it, bumping the shoulder 1 - 2 thousandths pulls the neck out of alignment. I surmised that there was not enough body support and the case was being bulged out sideways and pulling the neck crooked like fguffey is saying. The Forster FLS pushes the neck diameter down too far. Since I don't use the expander button, it is necessary to use my K&M expander on it and that results in crooked necks too, I presume from moving the neck wall down .005" +with the FLS and then back out with the expander.

I was searching for what die to get to do the job right when I remembered I had a Redding small base die I bought a while back. It sizes the body a bit more than I need, but I only need to fire it once to be good for about 5 more neck sizing sessions. It worked like a charm. When properly adjusted, it bumped the shoulder back without affecting neck concentricity. I then partial size the neck with the Lee collet die and it is perfect. What amazed me is that the neck stays straight no matter how much I bump the shoulder (I've gone up to 5 thousandths while working out the adjustment procedure). It also doesn't matter if I size the neck first with the LCD. It still stays straight when I bump the shoulder back.

This is working for me. YMMV