Polishing a body die?

[Bart B]

As I said in post 17, it would take a very long chapter to fully explain shoulder setback. There are a jillion different calibers, hard primers, soft primers, light/fast firing pins, heavy/slow firing pins, that affect shoulder setback.

I know all that.

But I don't think you quite understand that any bottleneck case headspacing on its shoulder has its shoulder hard against the chamber shoulder when the round fires. And it's held there while the case expands pushing the back part of the case against the breech face. Proof's seen by powder residue typically showing up on case necks, but not on the case shoulder.

Therefore, such shoulders are not blown forward as you say. And I explained why in one or two sentences.

But I used to think that way years ago until a 'smith showed and told me how to find out for sure.

 

[Innovative]

Bart B ......

When you see that 99.9% of all case head separations are at the rear of the case . . . . . it's obvious.

The amount of shoulder setback is the big variable.

Getting technical information (like this) from the Internet is sometimes like trying to take a drink of water at the base of Niagara Falls . . . . . there's a whole lot coming, it never stops, and you might not get exactly what you're after.

I don't recommend polishing the die in this situation.

 

[Bart B]

.[/B]9% of all case head separations are at the rear of the case . . . . . it's obvious.

That's not the reason.

It's partially the thinner case body wall at the shoulder and thicker case wall at the head that causes it as the front part of the case is pushed hard against the chamber wall long before the back part is. It's the back part that does most of the stretching.

The other part is the pressure ring area is where maximum work hardening of the case is at from enlarging when fired to reducing when sized down. The head and back 1/8th inch of the case changes diameters very little. It starts 2/10ths inch in front of it is. That weakens the case body at that point.

Rarely, if ever is there such a thing as "shoulder" separation. The case head breaks off from all the elasticity being removed from the brass at the pressure ring.

 

[Bullet bumper]

That's not the reason.

It's partially the thinner case body wall at the shoulder and thicker case wall at the head that causes it as the front part of the case is pushed hard against the chamber wall long before the back part is. It's the back part that does most of the stretching.

The other part is the pressure ring area is where maximum work hardening of the case is at from enlarging when fired to reducing when sized down. The head and back 1/8th inch of the case changes diameters very little. It starts 2/10ths inch in front of it is. That weakens the case body at that point.

Rarely, if ever is there such a thing as "shoulder" separation. The case head breaks off from all the elasticity being removed from the brass at the pressure ring.

Bart is correct on this . Polishing a die is no big deal if you start with something that is too tight to start with and don't go any further than you need to size the case to fit with some chambering clearance. Head space will not be affected if you cut the shoulder section away from the lapp before you start . That way you only lapp the body diameter out .
I have lapped a few dies and had no problems it's not rocket science .

 

[Innovative]

Bullet Bumber .......

You're right, this is definitely not rocket science. However, as a die manufacturer, and after taking jillions of phone calls from shooters (every day for the last 12 years), I can tell you that most shooters should be more interested in adjusting their die height accurately.

 

[Bart B]

...I can tell you that most shooters should be more interested in adjusting their die height accurately.

Very well put.

I'm convinced that most reloaders do not know how to accurately adjust their sizing dies. Especially when the common way is to "twist the die 1/4th turn" between sizing tests.

How many reloaders know that a 1/4 turn on a die moves it about .018"?

How many can figure out why?

When I say "most" that means the smallest fraction over half of them makes it a true statement. 501 reloaders out of 1000, for example.

 

[jsthntn247]

Well, tell me if I am doing it correctly then. I start with the die not contacting the shell holder when the ram is all the way up. I make very small turns on the die and check the headspace on my gauge and chamber the brass in my rifle after each turn. Since i go so slow and I've done it so many times, I can fell when I get a .001 bump just by how the brass feels when chambered in the rifle. However I always check with the gauge first. I have found that setting the die up to the manufacturers recs can result in as much as a .015 bump. I also put a magic marker mark on the datum line so I can visually see when it's touched.

 

[Innovative]

jsthntn247 ........

How your handloads "feel" as they chamber doesn't tell you what part of the case is fitting tight. The "Magic Marker" method will. However, there are several more accurate methods than that.

The most consistently accurate method I've found is described on the homepage of my website at WWW.LARRYWILLIS.COM There are also dozens of pages that explain things that you probably won't see in the gun magazines.

 

[Bart B]

The most consistently accurate method I've found is described on the homepage of my website at WWW.LARRYWILLIS.COM There are also dozens of pages that explain things that you probably won't see in the gun magazines.

Checked your site and found the following sentence printed first in your "Understanding Headspace" page:

The term headspace means the "space" between the "head" of your case and the breech.

The picture of the case (image named "headspace" with arrows pointing to where to measure chamber clearance when comparing your handloads to a fired case is shown below:

Isn't the head of the case at the bottom in that picture and will be only a few thousandths in front of the breech? The dimension shown in that picture is inches greater that the space between the breech and case head; on a .300 Wby Mag case, it's 2.384 inches and is definitely not the space between the bolt face (the breech) and case head in one of Roy Weatherby's rifles chambered for that cartridge. A .300 Wby Mag heaspace GO headspace gauge measures .219" from its head to the front of the belt.

The "space" between the "head" of your case and the breech is more commonly called "head clearance" in the 'smithing business.

This is confusing information, in my opinion. for lots of folks.

 

[Pdvdh]

Well, tell me if I am doing it correctly then. I start with the die not contacting the shell holder when the ram is all the way up. I make very small turns on the die and check the headspace on my gauge and chamber the brass in my rifle after each turn. Since i go so slow and I've done it so many times, I can fell when I get a .001 bump just by how the brass feels when chambered in the rifle. However I always check with the gauge first. I have found that setting the die up to the manufacturers recs can result in as much as a .015 bump. I also put a magic marker mark on the datum line so I can visually see when it's touched.

I think you're doing this correctly. I think your chamber diameter is too large in comparison to the resizing die, as someone suggested earlier. As much shooting as you appear to do, I think the best solutions were recommended by 'Mikecr' and 'Bullet bumper'. 'Mikecr's will require a bit more money, and 'Bullet bumper's will require more time. I'd select the one I had the most of

 

[Bart B]

Well, tell me if I am doing it correctly then. I start with the die not contacting the shell holder when the ram is all the way up. I make very small turns on the die and check the headspace on my gauge and chamber the brass in my rifle after each turn. Since i go so slow and I've done it so many times, I can fell when I get a .001 bump just by how the brass feels when chambered in the rifle. However I always check with the gauge first.

Using your gauge is a good thing to do.

If you measure the fit by "feel," but index your case in the chamber with a mark on its head put at 12, 3, 6 and 9 o'clock in the chamber, you may find the feel of a binding bolt to go away at two points. This indicates both the bolt face and case head is not squared up; a normal thing with commercial rifles. Which is why a .002" shoulder setback on fired cases is most often the best way to full length size fired ones from commercial rifles.

 

[Innovative]

Bart B .....

Whenever you take a few words out of context from a long article, it usually is confusing.

Once a gunsmith installs a rifle barrel, the headspace is done. It is permanently set until the barrel is reinstalled or replaced.

With most rifle calibers, handloaders could simplify their understanding of properly fitted handloads if they used the term "shoulder clearance".

Whether you are handloading a belted case, a rimmed case or a non-rimmed case . . . . it is best to minimize the "shoulder clearance" that your handloads have in your particular chamber.

 

[Bart B]

With most rifle calibers, handloaders could simplify their understanding of properly fitted handloads if they used the term "shoulder clearance".

Whether you are handloading a belted case, a rimmed case or a non-rimmed case . . . . it is best to minimize the "shoulder clearance" that your handloads have in your particular chamber.

The issue is, that's not what the firearms industry has suscribed to. Get SAAMI to put it in their glossary along with everyone else in the firearms industry and that will help your crusade be successful.

Meanwhile, any correctly sized bottleneck case headspacing on its shoulder (which everyone ends up with by setting fired bottleneck case shoulders a thousandth or two) will have zero "shoulder clearance" when it's chambered in a rifle with an in-line axial ejector in its bolt face. For all the rest, "shoulder clearance" will be zero when the round fires. This is what folks need to know and understand. This goes along with the industry and SAAMI standard of "head clearance" relating to such things.

With new bottleneck cases, there will be "shoulder clearance" with belted and rimmed cases when they're chambered and fired, but never ever with a rimless case.

 

[Bullet bumper]

The thread is decending into a ****ing contest between Larry and Bart and over complicating the issue .