How do you straighten runout?

[Mikecr]

Cartridges chambered with alot of clearance(including HS), that are not jammed, do not float, and are not centered. They 'lay' in the chamber cocked at whatever angle the extractor biases and the neck/shoulder clearances allow. With this, there is no concentric pre-firing condition at all. Nor would there be with perfectly STRAIGHT ammo, and I can't imagine anyone suggesting otherwise.
Now if bullets are jammed and there are relatively large clearances, then of coarse it is possible.
That's the qualifier that is often denied or disregarded by competitors, who must FL size irregardless -to group shoot within conditions.

With minimal body sizing, minimal HS(<1thou), and partial neck sizing, we can get closer to concentric pre-firing, even when bullets are seated off jam.
Hunters do not have to FL size the better cartridges, and we can make perfect ammo without bending loaded round necks.
It just takes a little more work, as anyone should expect.

 

[BountyHunter]

Cartridges chambered with alot of clearance(including HS), that are not jammed, do not float, and are not centered. They 'lay' in the chamber cocked at whatever angle the extractor biases and the neck/shoulder clearances allow. With this, there is no concentric pre-firing condition at all. Nor would there be with perfectly STRAIGHT ammo, and I can't imagine anyone suggesting otherwise.
Now if bullets are jammed and there are relatively large clearances, then of coarse it is possible.
That's the qualifier that is often denied or disregarded by competitors, who must FL size irregardless -to group shoot within conditions.

With minimal body sizing, minimal HS(<1thou), and partial neck sizing, we can get closer to concentric pre-firing, even when bullets are seated off jam.
Hunters do not have to FL size the better cartridges, and we can make perfect ammo without bending loaded round necks.
It just takes a little more work, as anyone should expect.

That is one side, but there is another that greatly differs and they focus on reliability and maximum accuracy which is what LR hunters should also.

The Rifleman's Journal: Reloading: Partial Neck Sizing

Too many times the NS vs FL size issue gets confusing to newbies as they think NS only vs what you advocate (partial NS and minimally body size).

I think most of the bushing dies (except the Neil Jones which are designed to come all the way down to an on the shoulder) leave a miniscule unsized portion of the neck anyway.

As I see your explanation, you are just doing it in two steps with a NS die and honed body die, correct?

BH

 

[Bart B]

Here's what happens in my own (and virtually all others I know of) SAAMI minimum spec'd chambers and fired .308 Win. cases that are full length resized reducing body diameters about 2 thousandths, setting the case shoulder back 2 thousandths and the FL die's neck sizing the whole case neck down such that the case mouth's about 1/1000th inch smaller than bullet diameter.

When the round's chambered and bolt closed, the inline ejector's spring pushes the case forward until its shoulder stops in the chamber shoulder. When the firing pin strikes the primer, that further drives the case shoulder hard into the chamber shoulder. The front of the case gets well centered in the chamber at the shoulder because the shoulder shape of both are the same; centering is very precice. And the case neck's also well centered in the chamber neck as it's centered on the case shoulder. Doesn't matter how much clearance there is around the case neck to the chamber neck; centered is centered. Note that the case shoulder typically gets set back a thousandth or more when the firing pin strikes with its 25 to 30 pound force.

At the back end where the extractor's pushing the case head up (for bolt face estractors that slide sideways such as the Winchester push-feed ones, sideways for Mauser style claw extractors that push the case sideways) until the case stops against the chamber wall. In some instances, the case rim will stop against the bolt face shroud if its tolerances and that of the chamber and case rim allow. But the case head always goes to the same point. Doesn't matter if the back end of the case is a thousandths or two off chamber center; it's repeatable and that is what's important..

With a round with zero bullet runout and its shoulder firmly well centered in the chamber shoulder, for each 1/1000th inch off center the case head is, the bullet tip will be about half that amount. More importantly, every round's seated in the chamber at the same angle and direction. The system's very repeatable.

As all cases and chambers are not perfectly round, it's a good idea to ensure no part of the case body interferes with the chamber walls. Full length sizing the fired case body does this. And the fired case body diameters need be sized down more than 2/1000ths.

Put a primed case in your rifle, then put a long rod down the muzzle so it rests on the case bottom around the flash hole. With a dial indicator set to measure how much the rod moves in and out of the barrel, you can usually push the rod down compressing the ejector spring and the case head will stop against the bolt face. Release the rod and it'll stop going out when the case shoulder stops against the chamber shoulder. The difference between these two measurements is the clearance your case headspace has to chamber headspace.

You can also use a case headspace gage (RCBS Prec. Mic?) to measure how much a primed rimless bottleneck case shoulder gets set back from firing pin impact. Ensure your firing pin spring is at factory specs for rating and the firing pin protrudes 50 to 60 thousandths from the bolt face in its fired position. Use a magic marker to blacken the shoulder of a primed case, chamber it, then remove it and you'll see the slightest marks where the ink shows contact with the chamber shoulder. Rechamber that primed case then fire it; the black ink now shows well defined marks showing it got driven hard into the chamber shoulder.

I learned this from Sierra Bullets first ballistic technician who reloaded cases testing most of their bullets from the 1950's though the middle 1980's. And my own various tests prove it so.

 

[Mikecr]

BH, yes you're reading me correctly.

Bart, I don't buy into cartridges consistently self centering on firing pin strike. But if centering actually is good enough on firing, then it wouldn't hurt a bit to have straight ammo with less or no clearances. Right?
It too will center, it just needs to adjust less in getting there..

 

[Bart B]

Bart, I don't buy into cartridges consistently self centering on firing pin strike.

Well then, where would any mechanical interference come from to prevent them centering at the shoulder? I'm not aware of any rifle parts that would prevent it.

But if centering actually is good enough on firing, then it wouldn't hurt a bit to have straight ammo with less or no clearances. Right? It too will center, it just needs to adjust less in getting there..

Of course, straight ammo always helps. But even perfectly straight rounds won't align perfectly on the bore axis. Their back end's always pressed against the chamber wall by the extractor.

Factory new commercial .308 Win. match ammo, even with 3/1000ths bullet runout, shot well enough in military match grade M14NM's and M1's to hold 4 inches or better at 600 yards. That's in a huge military spec chamber, too.

 

[nheninge]

Just don't forget to build them crooked and straighten them out later!

 

[SBruce]

Just don't forget to build them crooked and straighten them out later!

Seems like a real Smart *** reply to me. As did your first post in this thread, but more so this one.

I think we can all easily agree that building them without runout is definately more desireable, and should be the primary goal.

But the OP's question wasn't about building them, it was about straitening later. Straitening later is not the best way to go obviously, but it can be and has been done. Nobody builds something absolutely perfect everytime they do it, usless their name is God.

 

[nheninge]

going religious on me... wow . Smart ***... maybe. just pleasantly reminding people where this thread started. sounds like your ego is bruised a bit bruce. I love listening to a good debate... rage on .

 

[SBruce]

Perhaps my ego is a little bruised, never thought of it that way? More likely, just hit a bad nerve. I wasn't the one asking the question.

Seems to me that the OP was openly admitting that it's a learning process for them. As it was and still is for alot of us. I think alot more folks have tried straitening runout than will probably admit to it. Some just have tinkeritis.

I don't really consider myself religious, but I did once drop a 50# bag of bentonite on a guys head at work because I was done good and tired of his smart *** answers to serious questions. After he came to his senses and heard all the other roughnecks laughing, he said "why don't you watch what you're F$@@ng doing up there"? I said "why don't you quit being such a F$@@ng smart ***". He didn't think it was nearly as funny as all his smart *** commentary was, but everyone else did. Should have seen him, snow white head to toe, all except the pupils of his eyes. He wasn't a smart *** anymore, at least not to me.

Just think we should be careful of the stones we throw, even if they're only spit wads.

Cheers

 

[nheninge]

Congrats bruce. You can add bully to your blue collar resume! Feel free to ignore me as often as you wish, really, please. Not being a smartass, but even if I am... there is nothing you can do about it. Just trying to keep the humor light. I hope for your sake during your likely inevitable triple bypass, the doctors performing your surgery aren't having some sort of similiar coworker riff. Oops, the scalpel blade slipped. We regret to inform you mrs bruce...

Don't take life so seriously, you'll never get out alive.

Any other comments relative to the discussion at hand, please feel free

 

[Gone Ballistic]

Gentlemen and nheninge,
It never ceases to amaze me, as I peruse these threads in the forums, just how much help is voluntered by people that have experienced the issue being asked. Equally, as I have gleaned some very informative information, I eventually run across someone that would like to be a comedian, but couldn't ever make it. They don't lend one gram of good positive information to the inquirer, just perform inturruptive antics to respondents. It appears to me that they are starved for attention. They seem to feel, by being disruptive to respondants, they are self-served in some very demented way.
I was taught that "if you can't say something nice, don't say anything at all."
Nheninge, in your case, "It's better to remain silent and thought a fool than open thy mouth and remove all doubt!"
To the rest of you that have been so helpful, I can't thank you folks enough. I've learned some valuable information. SBruce, I'm flying down to Texas in a couple of weeks. You wouldn't have an extra sack of betonite you could spare, that I could deliver for you, by any chance?

 

[Bart B]

It's pratically futile to argue concentric -vs- straight ammo benefits, as nobody has proven one performance betters the other. But certainly there are huge differences between them.
I produce ammo that I verify is straight, because with that it is also concentric. It represents a low sum of errors from my entire reloading system and strategy.
Basically, it's the best I can achieve.

No response to my "floating" and "centering in the chamber shoulder" question, but here's another query anyway.

As there's no such thing as a perfectly round case, chamber or sizing die, what do you mean by "concentric?"

Perhaps to within a few ten-thousandths of an inch or so, which is typical. But that's enough to often cause interference between case and chamber walls when the case body diameters are not sized down enough.. And any interference there is will cause the barrel to whip a bit different for each shot. The end result is the bullet taking off in a slightly different direction upon its exit from the muzzle.

 

[ken snyder]

Never ever have I seen even the cheapest of brass go that far out of whack!!! at .002 I consider brass irretrievable junk. Something not good is happening. Try this : take the C clamp off of your shell holder and replace it with a rubber O ring to allow your cartridge to float in the press (align itself). While seating, seat down half way, pull cartridge all the way down and spin it 180º and finish seating. Something to remember while spinning for T.I.R. is that the bullet seats off the brass major diameter reguardless of its smallest radious and that spin jigs also are measuring base perpindicularity particularly when it is necessary to gauge on the ogive. I personally put very little stock in a spin jig! I prefer to measure neck thickness and do a good job of seating, because once you put a small cylinder into a larger round hole there is no possibilty of propoer bullet to bore alignment, unless something is hosed, as good as you can get is as good as geometry will allow.

 

[Bart B]

I personally put very little stock in a spin jig! I prefer to measure neck thickness and do a good job of seating, because once you put a small cylinder into a larger round hole there is no possibilty of propoer bullet to bore alignment, unless something is hosed, as good as you can get is as good as geometry will allow.

I don't like any of the cartridge spinners on the market. None of them measure runout based on how the case fits the chamber. Regarding your "small cylinder into a larger round hole," if that means case neck in chamber neck, the case neck does center in the chamber neck when the round's fired; read on.

Made my own cartridge spinner that has two places to support the round in V blocks exactly the same way it fits the chamber.

One V block at the back at the pressure ring, about 1/4th inch in front of the case head on rimless bottleneck cases or just in front of the belt on those kinds where the extractor holds it against the chamber wall with the round in the rifle.

The other V block's mid point on the shoulder as this is where the case centers at the front when it's fired. With the angle of both case and chamber shoulder being the same, the case perfectly centers in the chamber at it's front end.

My dial indicator's on the bullet ogive about 1/10th inch back from its tip. It doesn't matter if the case diameter at its pressure ring's a thousandth or two smaller than chamber diameter at that point. Every round will be oriented exactly the same for each shot. Even a 1/1000th spread in pressure ring diameter is meaningless.