Concentricity die choices, Where is the proof, general thoughts.

[nfngun]

OK I've been loading 223 with positive results with redding dies. My 308 is being built and again I plan on using the Redding bushing dies as I like there quality.

The debate goes on what is better the lee collet or bushing.

So aside from the concentricity gauge read outs. Where is the proof on paper that the Lee collet or the Redding is better then the other.

My .223 loads where just measured for the first time for concentricity, runout ect and all the specs where well within what's considered ideal.

So Im wondering where the proof is as far as accuracy goes, right now I look at it as 6 of one and a half dozen of the other. When it comes too lee collet and redding.

removing human error and out side conditions will the .0005 difference even translate onto paper with the most accurate of rigs be it a rail gun or other. I don't think it will.

Just something that's been turning my brain. As precision loaders we are literally splitting hairs. Using my Mitutoyo my hair measures .0015 so if I pull out all of my.002 and .0005 hairs will my head be more balanced for the perfect check weld.

Don't get me wrong I'm all about the details and if we can make it perfect why not try but at what point do I say to myself its time to talk to a shrink because the tools we use can out measure what the gun is able too do.

 

[Phil3]

The answer depends on the brass you are using and your gun. If the brass has no variance in neck thickness, then either method should theoretically work fine, with the bushing die giving the additional advantage of neck tension adjustments. You could do that with the collet die, if Lee will send you different diameter mandrels.

If the brass has substantial neck thickness variation, then the bushing die will make the outside neck concentric, but the inside of the neck (and bullet) will not be aligned with the case body. Using quality Lapua brass with minimal neck thickness variation makes this less of an issue, and perhaps even as good as the situation described in the previous paragraph.

Each gun will react to sizing practices differently and in unpredictable ways. Your gun may not care one way or the other, or it may shoot poorly with one approach. The evidence will be on the targets, assuming proper testing protocol is done. You need to test both approaches and see. I intend to do that with my 223 rifles.

Phil

 

[nfngun]

A box of Lapua is on the to buy list, hard to pull the trigger for the price, and since I'm not set up too anneal it'll kill me to toss lapua away.

 

[jcampbellsmith]

A box of Lapua is on the to buy list, hard to pull the trigger for the price, and since I'm not set up too anneal it'll kill me to toss lapua away.

I post my brass off for annealing when I need to get it done. At present I anneal after every fourth firing. Regards JCS

 

[sailhertoo]

I pull 4 hairs off my left side. The imbalance in weight offsets torque of the rifle. YMMV

 

[mikecr]

I do all I can to produce low runout ammo with bushing dies. No problems so far.
But,, I've yet to see science applied to define a point of runout that makes any difference.
It would be hard enough to prove an effect, much less define it..

Lapua brass is out of control on cost these days(like everything else). But if your chamber isn't way oversized, and you apply rational sizing to the cases, you can make 223 brass last forever, even without annealing.
I say buy 100 with a plan to make it last & never buy anymore.

 

[RStewart]

On my 14th .223 loads on my Lapua brass. Have not annealed yet. Have not encountered any issues.....yet.

 

[BoydAllen]

To answer your question requires knowing more than you have told us. Small things usually get "lost in the noise". This may be one of them. Tell us more about the .308. What is the chamber's neck diameter going to be? How do you plan on shooting it? What are your accuracy goals?

 

[Barlow]

If you are asking which dies are the most perfectly round, my experience is sizing dies are a crapshoot. Everybody make good ones and some bad ones. I have settled on Forster dies, but other makes satisfy many others. jmo Barlow

 

[broncman]

I have no desire to deal with donoughts created by bushing dies....
I have been using the redding full length body die that does nothing for the neck, and a lee collet die.

 

[TrxR]

How do bushing dies create the donut problem?

 

[BoydAllen]

If you do not stay on top of your shoulder bump, and only do the minimum that is required to get the feel that you need (checking to verify the amount of bump with a gauge) IMO you can end up with a doughnut with any die that sizes the body and bumps the shoulder, even a body die. Cases that are quite a bit thicker in the shoulder than the neck are particularly prone to this. Another big factor is the amount that a die reduces the diameter of the body of a case. Before and after sizing measurements of cases' shoulders will tell the story on that. All in all, I think that it is better to have a chamber that has a freebore that is long enough to keep bullets' shanks out of the area where doughnuts can form.

 

[Old Navy]

+1 especially on the last sentence. Later! Frank

 

[mikecr]

If you do not stay on top of your shoulder bump, and only do the minimum that is required to get the feel that you need (checking to verify the amount of bump with a gauge) IMO you can end up with a doughnut with any die that sizes the body and bumps the shoulder, even a body die.

I'm sure you meant 'and doing more than minimum required to get the feel you need(as measured)'.
With this, I totally agree.

OP I haven't seen donut forming from use of neck bushings alone.
As Boyd implied, and outside of upsizing necks/modifying the cartridge, donuts form from rolling brass up bodies -through body/shoulder sizing. It's amplified by case designs that present high body taper and low shoulder angles, as these will always require more in body correction/sizing with given loads than more improved designs.
You'll notice with FL sizing that first contact of the die is near the web, then mid body, upper body, and finally shoulder bump. This is rolling brass thickness upwards, thick to thin, like toothpaste from a tube.
These trouble case designs also stretch on firing, especially if not minding your headspace settings. You then FL size in the order described, and some of that brassy tooth paste comes into the neck and right out your trimmer.
That brass you're trimming away equals cases changing in thickness and capacity, growing at the neck shoulder junction, while thinning near the webs.

Also keep in mind that cases come brand new with donuts inherent to their forming. Cases are increasingly thicker from mouths all the way downward to webs. With this, donuts are already there, you can measure them, until you turn them out.
So this is one reason for sure to keep bullet bearing clear of neck shoulder junction,,, unless actually relying on a donut with some sort of bizarre neckless point blank BR cartridge(there is one out there).

 

[lurcher]

If you use a lee collet die and place a washer (say 40 thou width) over the brass before you size (hence not sizing the lower portion of the neck) would this negate the donut problem in the same way as never seating past the donut?

 

[BoydAllen]

No, because the case cannot expand larger than the chamber, so when the neck shoulder junction thickens, the ID is reduced, because the OD is limited. On the other hand, if the freebore is long enough so that the shank stays above the doughnut, it hardly matters one way or the other.

 

[mikecr]

Lurcher, if you're talking about doing what bushing dies do(partial neck sizing), then it's possible for this to alleviate the donut issue somewhat. It depends on whether your chamber neck is tapered or parallel.
Many SAAMI cartridges include neck taper by design(1-4thou greater OD at neck/shoulder junction).
http://www.saami.org/specifications_and_information/publications/download/206.pdf
If you expand necks after sizing here, the donut would reform into taper(go outside) and still chamber ok.

All of my current chamber necks are parallel. But I had a Lazzeroni cartridge/chamber once with tapered necks by design.
I can only imagine this feature was supposed to address donut. But I hated and soon got away from it.
I prefer to turn necks to consistent thickness and keep my necks that way.
There is another reason to keep bullet bearing away from neck shoulder junction, even without donut -additional/inconsistent neck tension. It's a pretty tough area to set dimension on with precision.

 

[BoydAllen]

I have always thought that factory chambers have tapered necks because unturned cases are thinnest at their mouths and taper continuously from there their heads, where they are thickest. If you want to keep a constant neck clearance from case mouth to the very back of the case neck, you have to have a chamber neck that is tapered. On the other hand, if you are turning necks, and want to maintain a constant clearance the back of the neck should be the same diameter as the front, making the shape cylindrical rather than a conic section.