Floating dies

[JimSC]

^^^^^^This is why all dies are not the same. So you are saying the shoulder gets pulled with the up movement of the press. Isnt this the main reason for floating a die? As I understand it its the Locking rings that work against us.

All dies are cut with a through reamer for one reason, cost effectiveness. Believe that or don't but it is true.

Now try putting a bolt in a vise and tightening the jaws then see if you can wiggle that bolt. When sizing a case you are squeezing that case in the die just like the bolt in the vise

BTW My press of choice since the biggest thing I reload is a .308 is the humble Lee Turret. Now that baby has some float

 

[Cecil S.]

All dies are cut with a through reamer for one reason, cost effectiveness. Believe that or don't but it is true.

Now try putting a bolt in a vise and tightening the jaws then see if you can wiggle that bolt. When sizing a case you are squeezing that case in the die just like the bolt in the vise

BTW My press of choice since the biggest thing I reload is a .308 is the humble Lee Turret. Now that baby has some float

Well I use a Coax and I feel this system helps with any imperfection in the die. But I am still a newbie.

 

[BoydAllen]

All dies are cut with a through reamer for one reason, cost effectiveness. Believe that or don't but it is true.

Now try putting a bolt in a vise and tightening the jaws then see if you can wiggle that bolt. When sizing a case you are squeezing that case in the die just like the bolt in the vise

BTW My press of choice since the biggest thing I reload is a .308 is the humble Lee Turret. Now that baby has some float

There are a couple of die makers who cut dies on turning centers using small boring bars. Harrell's is one, and I believe that the custom department at Hornady does theirs the same way. A friend has seen some small improvement in his sized brass concentriciy from doing a couple of small modifications to his press. IMO compared to actual testing, untested theories are way down on the list. This is not to say that your Lee does not produce results that are equal or better than presses that are a lot more expensive. The only way to know that would be by actual testing. If you are satisfied with the accuracy that you are getting, I would say that this is not a pressing issue. Pun intended.

 

[Bob3700]

The distribution of brass in the case does indeed affect accuracy. If you measure the thickness of your brass down at the head, you will find that this variation in wall thickness continues thru out the case. Once fired the thin side stretches more than the thick side and you get a banana shaped case. No amount of sizing will totally take this banana shape out of the brass. You can neck turn that brass all you want, but when fired, it will bend back into the banana shape.
Want to prove it to yourself? Measure the wall thickness of a small sample of your cases, mark either the thin nor thick side of the case. Load them up. Now when you chamber those rounds, place the rounds into the chamber with the index marks all oriented in the same direction. 12 or 6 O'clock, doesn't matter as long as the are all indexed the same. Your groups will be consistent and smaller.
Take that same group of cases and chamber the index marks 90 degrees to each other around the clock. Shoot another group. The bullet impacts will follow the indexed mark.
So, just because your turned brass has low runouts (if the distribution of brass in your cases isn't even) then your groups will suffer from the banana cases. The sizing die you use cannot make a good case out of a bad one.

 

[JimSC]

There are a couple of die makers who cut dies on turning centers using small boring bars. Harrell's is one, and I believe that the custom department at Hornady does theirs the same way.

Thanks for the info, that will be my "learned something new today". Having worked with machinery and manufacturing my entire life I just don't see any logical way that the brass could be out of concentric at the moment it breaks contact with the walls of the die.

I can see the expander ball pulling the neck off-center slightly as it passes back through. Possibly uneven neck thickness could cause that even if the expander ball was removed and a mandrel used.

If using a gage that indexes with the base, such as the Hornady does, a bolt that is not square with the receiver could be the root cause. I know my AR brass gives me a lot more concentricity issues than my bolt gun brass does.

I can also visualize a base being pushed or pulled out from perpendicular with a cocked shell holder. Although considering the pressure required that would be something of a stretch.

I don't think that that same shellholder applying more pressure on one side of the case than the other could tweak a neck is much of a stretch. That possibility could be a good argument for the O ring under the locknut trick

I don't claim to know all or even any of the possible whys, but I am 99.99999% certain the neck of the die not being concentric with the body portion is not the issue

Edit - Just to throw a monkey wrench into the thread there is the old argument that when the brass is laying in the chamber it is tilted slightly upward so why does it matter? I think I just channeled Bart

 

[BoydAllen]

Thanks for the info, that will be my "learned something new today". Having worked with machinery and manufacturing my entire life I just don't see any logical way that the brass could be out of concentric at the moment it breaks contact with the walls of the die.

I can see the expander ball pulling the neck off-center slightly as it passes back through. Possibly uneven neck thickness could cause that even if the expander ball was removed and a mandrel used.

If using a gage that indexes with the base, such as the Hornady does, a bolt that is not square with the receiver could be the root cause. I know my AR brass gives me a lot more concentricity issues than my bolt gun brass does.

I can also visualize a base being pushed or pulled out from perpendicular with a cocked shell holder. Although considering the pressure required that would be something of a stretch.

I don't think that that same shellholder applying more pressure on one side of the case than the other could tweak a neck is much of a stretch. That possibility could be a good argument for the O ring under the locknut trick

I don't claim to know all or even any of the possible whys, but I am 99.99999% certain the neck of the die not being concentric with the body portion is not the issue

Edit - Just to throw a monkey wrench into the thread there is the old argument that when the brass is laying in the chamber it is tilted slightly upward so why does it matter? I think I just channeled Bart

First question, do you own a concentricity gauge? Second question, if you do have you used it a lot to measure sized cases? Third question have you done a lot of experimenting to try to have the straightest possible ammunition?

 

[JimSC]

First question, do you own a concentricity gauge? Second question, if you do have you used it a lot to measure sized cases? Third question have you done a lot of experimenting to try to have the straightest possible ammunition?

1) Two, the Hornady and the 21st Century

2) again yes. .001 - .002 on my bolt gun cases, .001 - .005 on my semi auto cases depending on which gage I use. That is why I think the semi autos, .308, 6.5 Grendel, 6 ARC, and 223, bend or just damage the rims and case bases. The Hornady shows more runout than the 21st Century with those. The Hornady of course indexes off the case rim/base The 21st Century off the case body. On my bolt rifle cases both tools give the me same numbers.

Now that I have developed a system both just sit on the shelf most of the time. I will do random checks now and again but I think my runout results are about as good as possible, at least with my bolt rifle cases.

3) I first went from non bushing to Redding S bushing dies, when that did not cure it I switched to body dies followed up by Lee neck sizing dies for the cartridges where possible. That was an improvement but I still wanted better. I ended up with a 3 Step system. Depriming with a universal, then sizing using either FL non bushing or a bushing die with the expander ball removed, and then I expand the neck using an expander mandrel for the final step. Three operations instead of one but that is what has given me the best results. I have also played with different lubes but that did not seem to affect my results and now I use either lanolin homemade on large batches or Imperial if less than 25 or so cases

Edit - I also played with putting the O rings under the dies and removing the spring clip from the ram's shell holder slot and using an O Ring to hold them in place instead

 

[BoydAllen]

1) Two, the Hornady and the 21st Century

2) again yes. .001 - .002 on my bolt gun cases, .001 - .005 on my semi auto cases depending on which gage I use. That is why I think the semi autos, .308, 6.5 Grendel, 6 ARC, and 223, bend or just damage the rims and case bases. The Hornady shows more runout than the 21st Century with those. The Hornady of course indexes off the case rim/base The 21st Century off the case body. On my bolt rifle cases both tools give the me same numbers.

Now that I have developed a system both just sit on the shelf most of the time. I will do random checks now and again but I think my runout results are about as good as possible, at least with my bolt rifle cases.

3) I first went from non bushing to Redding S bushing dies, when that did not cure it I switched to body dies followed up by Lee neck sizing dies for the cartridges where possible. That was an improvement but I still wanted better. I ended up with a 3 Step system. Depriming with a universal, then sizing using either FL non bushing or a bushing die with the expander ball removed, and then I expand the neck using an expander mandrel for the final step. Three operations instead of one but that is what has given me the best results. I have also played with different lubes but that did not seem to affect my results and now I use either lanolin homemade on large batches or Imperial if less than 25 or so cases

Edit - I also played with putting the O rings under the dies and removing the spring clip from the ram's shell holder slot and using an O Ring to hold them in place instead

We have done the same things. One thing that I did discover, beyond all of that was that if you are dealing with turned necks, a one piece die that has a neck ID such that no expansion is required to have the desired neck tension will yield the straightest sized brass. I discovered this because the least expensive Hornady 6PPC die's neck ID sizes necks to the same OD that a .258 bushing would, which works as is for my brass that has been turned for a .262 neck chamber. While this is a little less neck tension than I prefer for 133, it is just fine for LT32. Sized brass has about a third of a thousandth runout at the end of the case neck.

Back in the day, someone who I tend to believe told me that on the bullet (measureed about where the rifling will make contact) runout of .002 or less will not affect targets. Since then I have never seen or read anything that would disprove this. For my PPC, typical loaded round runout runs around .0015, so even though bushing dies are not perfect, I would say that if they produce these kinds of results, that they are generally good enough. For unturned necks, my experience has been that two step sizing using a LCD and a properly set body die gives the best results for loaded round runout.

I have seen slight improvement in runout comparing a standard lock ring co a Lee lock ring, set so that the O ring is under slight compression.

Recently, I have seen multiple reports that the SAC bushings that fit where Wilsons would, produce consistently better runout. I have discussed their design with the manufacturer and this improvement in performance is due to a unique profile of the inside of the bushings.

 

[6BRA]

SAC are tapered and work well if you like bushings. They decrease neck tension due to taper. As far as arguing a fixed threaded die vs a floated coax die....it's just nuts imo. A floated system can't be beat. Eliminate the expander ball/ eliminate the mandrel and you will see less than .0005 tir. It's also nuts to think you can sort bullets on overall length. Base to ogive is the only worth while sorting method. Even the best have BTO differences of .003 or more across 500 bullets. And that includes the best of the best hand pulls.

 

[Cecil S.]

There are a couple of die makers who cut dies on turning centers using small boring bars. Harrell's is one, and I believe that the custom department at Hornady does theirs the same way. A friend has seen some small improvement in his sized brass concentriciy from doing a couple of small modifications to his press. IMO compared to actual testing, untested theories are way down on the list. This is not to say that your Lee does not produce results that are equal or better than presses that are a lot more expensive. The only way to know that would be by actual testing. If you are satisfied with the accuracy that you are getting, I would say that this is not a pressing issue. Pun intended.

Listen and learn this is what this site is all about. Very deep knowledge to draw from.

 

[searcher]

Are any of y'all floating everything on press
Let's say you have dies that have floating parts in them Redding competition seater die, bushing dies,mandrel die.
And even floating shellholder with rubber o-ring.
I'm going to give it a try but was wondering y'all's experience and wondering effects of floating everything including die, shellholder along with the dies I've mentioned.
I know there's been plenty of discussion but wasn't sure if those discussions meant everything on the press.

I always keep my threaded dies loose, as I've never had a press that had a 100% straight bore for the dies. I use a magic marker to note the position of the locking ring as it sits in the press by putting a line on the outer edge of the locking ring and a corresponding registration mark on the top of the press. I monitor it for movement as I load. I usually see the registration lines start to wander about every 15 rounds sized. But even a 1/16th move on the registration line amounts to almost nothing in seating depth or bumping a shoulder. I trade any small deviation for getting straighter cases and less loaded ammo runout. I don't use O-Rings as I found brass compresses almost as easily as they do.

 

[wk4036]

The only thing I have floating is the shell holder in my R C press. I removed the metal retainer/pin and replaced it with an O-ring. This allows the brass to follow the die without any horizontal pressure.

Any pics?

 

[Bill Norris]

Any pics?

Here you go.

 

[Jeff N]

Here you go.

@Bill Norris, great photo. Appears to be the the same as I use - 7/8 OD x 11/16 ID x 3/32 (Danco #13, Everbilt #90).

 

[Bill Norris]

Yep Danco #13