Loaded ammo bullet runout???

[Mikecr]

There are a lot of qualifiers that need to be assigned to what you declare Bart.
Yes, point blank BR runs extreme pressures with their tiny 6PPC. They do this because they can & it's the ultimate work-around for pretty much all else internal except the barrel itself.
Running extreme pressures gives you no choice but to FL size, and this in no way means NOT FL sizing(or minimally sizing with custom dies) is bad. It means they must do it, and that's all.

The rest of us in the shooting world cannot run the same pressures, because useful cartridges are considerably larger. Our chambers will not get anywhere close to common 6PPC pressures before the bolt has to be beaten open.
You seem to be generalizing that because BR shooters win with FL sized cases, then they MUST be FL sized to shoot well.
NO, they don't have to be FL sized to shoot 'well'(~.25moa is well for hunting).
A 6PPC could be loaded to shoot 'well' at far lower pressures. In fact, plenty low enough that FL sizing is NEVER needed.
And otherwise it's just a poor measuring stick for us hunters anyway.

Cases that vary in thickness around their perimeter do spring back to bananas. FL sizing amplifies this. It NEVER reduces it.
So I can see your point that in using such cases, those exhibiting runout from the body, more clearances seem in order. But as usual, this is a choice that doesn't apply to us that chose otherwise.
I cull new cases with thickness variance out. I don't FL size. And my case bodies and shoulders provide well under 1thou of TIR.

It couldn't be easier to measure and see what I'm talking about. You take new cases, fireform them 3 times(no sizing) and drop them on Sinclair's best runout gauge. You BETTER see way below 1thou of TIR, anywhere unsized, or your chamber/barrel finisher sucks.
Now take these same cases and FL size them. Drop em on that gauge and see the resultant runout -you just added.
You can manage this one way, or another, but it IS a choice.

I think you embrace every shortcut you can,, and that you rationalize this as good enough.
But I doubt you could prove with a scientific method that shortcuts are actually best.
In what human endeavor ARE shortcuts best?
I can't think of any...

 

[RTK]

Check out the section starting with Custom Dies Work Best in this site: Speedy's 6PPC -- The Art of Accuracy

The reason they full length resize is to prevent interference between case body and the chamber wall that can cause the front of the case to no longer center perfectly up front at the chamber shoulder when too little clearance happens with neck only sized cases.

.

Isn't that because they are pushing them pretty hard as where others might not be, so this might not apply??????? More spring back and all???
I would think the tighter the fit (to a point) the more centered and concentric everything would be, not just at the neck, right before bullet launch.
I can't argue with the results of what the top BR boys are doing, I just wonder how applicable it is to me since I only neck size everything I own

edit:-Mike, thanks for your input, you confirmed my suspicions. Apples and Oranges. I'm just a hunter that likes to shoot distance at small and large targets. I also like to put holes in paper in nice small groups anything I can learn never hurts.

 

[Mikecr]

You're right RTK. Tighter CAN be more centered.
It's just not a viable option for high pressure loaders, or, those running poorly designed cartridges.

Whether this encompasses your situation, is really independent of 'top BR boys'.
You think through it and manage it yourself.
It's your choice.

 

[RTK]

I think you hit the nail on the head Mike. I've been reloading for over 30 years and have experimented with many things, some good some failures. I only neck size for all my bolts rifles with decent case prep procedures and have had pretty good results. Never to old to learn a new trick though.
The only 4 rifles I currently reload for are a 223, 22-250AI, 7mm and 300WM. I don't over push them either.

 

[Bart B]

Measure chambered cases' necks position in chamber necks. You may then understand. My measurements show no difference within 2/10,000ths inch until body diameters start getting close to chamber diameter. Full length sized cases had overall better centering than neck sized ones.

Unless you measure you may not believe it. If you understand why without measuring, that's good. It took a special gauge that is easy to make and a 15x scaled loupe.

 

[blkdog]

I just purchased the Hornady concentricity tool. It has a dial indicator and is adjustable to indicate where you want. You can also correct run out with a threaded thumbscrew. It works like it is supposed to. One other tip to avoid run out is to turn your loaded round 180 degrees and run it back through the die. I don't know why this works, but it does. Most of the time my run out is less than .002 and after running them through the Hornady tool you can get it down to "0". I hope this helps.

 

[Trickymissfit]

You're right RTK. Tighter CAN be more centered.
It's just not a viable option for high pressure loaders, or, those running poorly designed cartridges.

Whether this encompasses your situation, is really independent of 'top BR boys'.
You think through it and manage it yourself.
It's your choice.

I've long felt that a case with the very minimum taper built into it will not align itself to the bore as well as one that say have .030" taper in the body. But even then this is only as good as the bolt squares itself up with the chamber as it seats in the action. To a certain extent I put some of this error on the extractor itself (but you gotta have one). Everybody has their own way in chambering a loaded round. I prefer to headspace a tad on the tight side, but others don't.
gary

 

[Trickymissfit]

I just purchased the Hornady concentricity tool. It has a dial indicator and is adjustable to indicate where you want. You can also correct run out with a threaded thumbscrew. It works like it is supposed to. One other tip to avoid run out is to turn your loaded round 180 degrees and run it back through the die. I don't know why this works, but it does. Most of the time my run out is less than .002 and after running them through the Hornady tool you can get it down to "0". I hope this helps.

When you disturb the neck and bullet relationship to get it to center, you also bring into light a new set of problems. Your a lot better off starting out with a strait case prior to seating a bullet in the long run. I never index a case in my press. If I see .0035" TIR, I start to look around for a problem before ever seating a bullet.

By the way if that dial indicator is an analog one, your looking at 10% backlash in it or more (the Chinese ones often get in the 15% area). The digital ones work off a linear encoder, and are usually good for .0003"-.0006" (there is no provision to take out the backlash electrically on this type of indicator)
gary

 

[Mikecr]

My measurements show no difference within 2/10,000ths inch until body diameters start getting close to chamber diameter. Full length sized cases had overall better centering than neck sized ones.

But none of us have any idea what measures would occur on actual firing.

With FL/excess sizing, you're creating the very problems that you try to rationalize away as good attributes.
I think that if you make ammo that is actually straight, there is no need for band aids(like extra clearances) to get a gun shooting well. No need for fish tales.
And I think guns that shoot well enough with band aids, might do even better without.

It's not difficult to make straight ammo, and coincidently, to get a tight chamber fit(which creates straighter ammo) shooting well.
IMO, it's far easier all around -for well designed LR hunting cartridges.

 

[Bart B]

One other tip to avoid run out is to turn your loaded round 180 degrees and run it back through the die. I don't know why this works, but it does.

This usually happens with conventional seating dies when its bullet seating stem is off center in the bullet guide. There's enough clearance on some seating dies to wrap one layer of transparant tape around the seater head so there's zero clearance between it and the die body.

I've done a lot of measuring on cases to see how well their necks are aligned with their body using a bullet runout tool. Bullets tend to align themselves with the case neck axis when they're seated. If the case neck's not straight on the case, no bullet seater will make them seat straight. Crooked case necks will bend a bit in seaters with tight neck areas as the bullet's seated but will spring back to a bit crooked after the round comes out of the seating die.

 

[Boss Hoss]

Well for those of you that don't know Speedy and I know each other and if you want you can PM me and I will inform you what he said about this thread via an email lol. It was not complementary on the theory of not having a aboslute concentric relationship between the ammunition and the chamber.

 

[Bart B]

Well for those of you that don't know Speedy and I know each other and if you want you can PM me and I will inform you what he said about this thread via an email lol. It was not complementary on the theory of not having a aboslute concentric relationship between the ammunition and the chamber.

Why not put what he said in this thread so we all can get his opinion?

If it's a secret only to be revealed to special folks, why even mention it publically when a PM to those who might be interested might be in order?

This "secret stuff" has prevailed in the BR crowd for years. Those not considered worthy by BR folks of such information are never told what's going on in the BR world. Speedy's comments seem to be one of these secrets just like what's the biggest groups their "tack drivers" shoot are.

 

[Boss Hoss]

All it takes is a simple PM. If you don't care to know then fine. It is only one word so you don't get your expectations up for a detail response which in this case would not be appropriate.. Speedy is pretty blunt when speaking to me because that is the way we have always communicated--no fluff.

 

[Bart B]

All it takes is a simple PM. If you don't care to know then fine. It is only one word so you don't get your expectations up for a detail response which in this case would not be appropriate.. Speedy is pretty blunt when speaking to me because that is the way we have always communicated--no fluff.

Thanks for this information. So an emotional outburst of one word is better than several to insure understanding. I could respond in kind, but that would not be welcomed by its recipients.

I've got Speedy's street and email addresses and his phone number, I'll contact him and get better informed.