I'll shoot .2 groups with my 6ppc, but my .223 and .338LM are doing .75 to 1.25 consistently. I do the exact same thing with my .223 and .338LM that I do with my 6ppc , I start with new Lapua brass, turn necks, Debur flash holes, uniform primer pockets, resize using an RCBS Pardner press, Redding full-Length S-type bushing die, seat bullets with a Wilson micro-top bullet seater. I pulled out a Sinclair Concentricity guage. My 6ppc has less than a thousandth runnout on any round. The .223 and .338LM have as much as eight thousanths runout on some rounds, and average about three to four thousanths runout with a few under two thousanths. I don't understand how come I'm doing all the same things with the .223 and .338 as with the 6ppc, but not getting the same results. What else can I do to control runnout?
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Controling runnout?
- Thread starter JDBraddy
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Mikecr
Well-Known Member
Well w/regard to runout, the 6PPC is a way shorter banana than the other two cartridges.
Runout manifests in two ways:
Sizing/springback of thickness variance in cases
Poor bullet seating
The greater the thickness variance, and the greater your sizing of it, and the worse your seating(often caused by thickness variance), the greater your loaded runout rate.
So given this, the greater the length of case/COAL, the greater your measured runout.
That a 6PPC shoots way better though is irrelevant to runout I'm sure.
Runout manifests in two ways:
Sizing/springback of thickness variance in cases
Poor bullet seating
The greater the thickness variance, and the greater your sizing of it, and the worse your seating(often caused by thickness variance), the greater your loaded runout rate.
So given this, the greater the length of case/COAL, the greater your measured runout.
That a 6PPC shoots way better though is irrelevant to runout I'm sure.
Engineering101
Well-Known Member
Take a look at the Hornady concentricity checker/fixer. I don't worry much about run out but just fix whatever is there which varies from 0 to 0.008" or there abouts using RCBS equipment. My rifles with ammo thus fixed group in the 0.500" to 1.500" range at 200 yards which works for my application. I figure I'm causing at least 0.250" of that spread so there isn't a whole lot more improvement to be had. Before I started fixing concentricity I got flyers on a regular basis which made a mess of group size.
Mikecr
Well-Known Member
Runout is different than eccentricity.
And you can't 'fix' crooked ammo with a neck bender..
Straight ammo is also concentric ammo. But concentric ammo can be crooked as hell.
So it's best to make straight ammo, which is lower in chambered tension.
And you can't 'fix' crooked ammo with a neck bender..
Straight ammo is also concentric ammo. But concentric ammo can be crooked as hell.
So it's best to make straight ammo, which is lower in chambered tension.
Engineering101
Well-Known Member
Mikecr
I have to admit that I thought that concentricity and run out were the same. I think I understand what concentricity is. If you spin something and it doesn't wobble it has no concentricity errors. So what exactly is run out? How would you recognize it? Thanks in advance for the education.
I have to admit that I thought that concentricity and run out were the same. I think I understand what concentricity is. If you spin something and it doesn't wobble it has no concentricity errors. So what exactly is run out? How would you recognize it? Thanks in advance for the education.
Mikecr
Well-Known Member
I'll try to explain.
For one, 'concentricity' gage is a misnomer.
We have either runout gages(V-block), or eccentricity gages(neck-benders). I spell it 'gage' here for simplicity.
The confusion between runout and eccentricity stems from machining measure, which is often taken to a center-line(i.e. lathe). Gun builders, gunsmiths, & machinists with shooting hobbies, have asserted this(influenced it). Well, a free cartridge has no center-line. chambering a round is not placing it between centers. So forget centering of cartridges, as this never happens in application. Where is the chambered & fired bullet pointed? You don't know, and can't know with any precision.
RUNOUT is the sum of all errors -from straight. Some errors worsening result,, some cancelling,, some improving.
Runout is an inescapable reality in our loaded cartridges, separate from and irregardless of any bench centered measure. When we chamber a round, it's runout that comes into play. It's this non-straightness that causes chambering tensions, which are not-good for shooting precision.
If you've read Vaughn's 'Accuracy Facts' you likely picture firing a round as a hammer strike to the chamber end of your barrel.Rifle Accuracy Facts Book by Harold R. Vaughn
This, sending radial & surface waves of energy back & forth at the speed of sound in your steel. Your bullets are muzzle released amidst this noise, and it gets very complicated. The noise is summing and cancelling, and changing as the bullet goes down the bore, untwisting and forcing out droop tension in the barrel. Rest your thumb anywhere along the path and watch a shot throw off from expected grouping. The waves are so easily influenced, yet below practical measure and prediction.
We just tune with tensions and interferences in-place, and try not to cause any change from tuned condition.
Ripples on a pond..
The hammer strike to a barrel happens as it does, and not always exactly the same. Firing chambered bananas is enough to source energy from different coordinates around a chamber. Like dropping a stone into water a little left of where it was dropped before.
Some would argue that it doesn't matter, that amplitude is still the same overall & little timings of noise don't show up on paper targets. Well, it is a minor factor in our precision, I'll give it that. Many shooters could not isolate it with their shooting system.
If you've got a big ole sloppy chamber, or your gun doesn't shoot with much of a barrel tune anyway, you probably don't see or care about the affects of loaded runout.
We can make straight ammo. I do it all the time.
We don't need to fool ourselves about it, assume it, or play games with it. We can Just do it and verify it as measured on a V-Block runout gage. Where we can't make low runout ammo, it's easy enough to understand why.
So what is the difference in ammo measure with a runout gage -vs- an eccentricity gage?
I'll show you with pics, 1st the bad.
#1-3 show a round measured on a 'concentricity gage', and that no matter how crooked the ammo actually is -it still measures low.
#4 shows the same ammo/gage having it's 'bullet adjusted' for a lower reading.
Notice the ammo is still nowhere near straight..
The reason ought to be obvious; the indicator is very near a pinned end of the ammo(the bullet tip). With this, most runout is dismissed from measure.
Picture a jump rope. If you wanted to measure the amplitude of it's arc(runout), you wouldn't do so near an end, but at the center. So why are all eccentricity gages set up with so much error(measuring at a stationary end)?
The answer is marketing. To make you feel like your ammo is constructed & 'adjusted' better than actual.
For one, 'concentricity' gage is a misnomer.
We have either runout gages(V-block), or eccentricity gages(neck-benders). I spell it 'gage' here for simplicity.
The confusion between runout and eccentricity stems from machining measure, which is often taken to a center-line(i.e. lathe). Gun builders, gunsmiths, & machinists with shooting hobbies, have asserted this(influenced it). Well, a free cartridge has no center-line. chambering a round is not placing it between centers. So forget centering of cartridges, as this never happens in application. Where is the chambered & fired bullet pointed? You don't know, and can't know with any precision.
RUNOUT is the sum of all errors -from straight. Some errors worsening result,, some cancelling,, some improving.
Runout is an inescapable reality in our loaded cartridges, separate from and irregardless of any bench centered measure. When we chamber a round, it's runout that comes into play. It's this non-straightness that causes chambering tensions, which are not-good for shooting precision.
If you've read Vaughn's 'Accuracy Facts' you likely picture firing a round as a hammer strike to the chamber end of your barrel.Rifle Accuracy Facts Book by Harold R. Vaughn
This, sending radial & surface waves of energy back & forth at the speed of sound in your steel. Your bullets are muzzle released amidst this noise, and it gets very complicated. The noise is summing and cancelling, and changing as the bullet goes down the bore, untwisting and forcing out droop tension in the barrel. Rest your thumb anywhere along the path and watch a shot throw off from expected grouping. The waves are so easily influenced, yet below practical measure and prediction.
We just tune with tensions and interferences in-place, and try not to cause any change from tuned condition.
Ripples on a pond..
The hammer strike to a barrel happens as it does, and not always exactly the same. Firing chambered bananas is enough to source energy from different coordinates around a chamber. Like dropping a stone into water a little left of where it was dropped before.
Some would argue that it doesn't matter, that amplitude is still the same overall & little timings of noise don't show up on paper targets. Well, it is a minor factor in our precision, I'll give it that. Many shooters could not isolate it with their shooting system.
If you've got a big ole sloppy chamber, or your gun doesn't shoot with much of a barrel tune anyway, you probably don't see or care about the affects of loaded runout.
We can make straight ammo. I do it all the time.
We don't need to fool ourselves about it, assume it, or play games with it. We can Just do it and verify it as measured on a V-Block runout gage. Where we can't make low runout ammo, it's easy enough to understand why.
So what is the difference in ammo measure with a runout gage -vs- an eccentricity gage?
I'll show you with pics, 1st the bad.
#1-3 show a round measured on a 'concentricity gage', and that no matter how crooked the ammo actually is -it still measures low.
#4 shows the same ammo/gage having it's 'bullet adjusted' for a lower reading.
Notice the ammo is still nowhere near straight..
The reason ought to be obvious; the indicator is very near a pinned end of the ammo(the bullet tip). With this, most runout is dismissed from measure.
Picture a jump rope. If you wanted to measure the amplitude of it's arc(runout), you wouldn't do so near an end, but at the center. So why are all eccentricity gages set up with so much error(measuring at a stationary end)?
The answer is marketing. To make you feel like your ammo is constructed & 'adjusted' better than actual.
Attachments
Mikecr
Well-Known Member
Now look at the same cases on a runout gage at #5-7
There is no straightening, no concealing, just the brutal truths. Your ammo is either straight or it isn't. If I took the round straightened off a neck-bender and dropped it on a runout gage, any dillusion former dissolves -#8
There is no straightening, no concealing, just the brutal truths. Your ammo is either straight or it isn't. If I took the round straightened off a neck-bender and dropped it on a runout gage, any dillusion former dissolves -#8
Attachments
Engineering101
Well-Known Member
Mikecr
That was a good explanation. I printed that stuff out to keep. Thanks for taking the time to clue me in. It looks like I need to upgrade my equipment. What run out gage do you recommend?
That was a good explanation. I printed that stuff out to keep. Thanks for taking the time to clue me in. It looks like I need to upgrade my equipment. What run out gage do you recommend?
Mikecr
Well-Known Member
I've been using Sinclair since the dawn of time
http://www.sinclairintl.com/reloadi...s/sinclair-concentricity-gauge-prod37479.aspx
Notice they call it a concentricity gauge -it's a v-block runout gauge.
The best is Accuracy One
New Wheel-Drive Concentricity Gauge from Accuracy One « Daily Bulletin
They call this a concentricity gauge as well!
Ignorance is powerful...
http://www.sinclairintl.com/reloadi...s/sinclair-concentricity-gauge-prod37479.aspx
Notice they call it a concentricity gauge -it's a v-block runout gauge.
The best is Accuracy One
New Wheel-Drive Concentricity Gauge from Accuracy One « Daily Bulletin
They call this a concentricity gauge as well!
Ignorance is powerful...
Mikecr
Well-Known Member
Back to Op's wondering about runout control.
Remember what I said about the cause of runout earlier;
-Sizing/springback of thickness variance in cases
-Poor bullet seating
You're using Wilson inline seating, which helps a lot, but you're still FL sizing long cases.
The cartridges 223rem and 338LM are poor cartridge designs w/resp to making and maintaining straight ammo. They both hold low shoulder angles and high body taper, and they're long for diameter. With this, you have no choice but to FL size the 223, if using hot loads, and no choice at all about FL sizing with the 338 either way.
FL sizing moves brass. It brings springback into play. It does nothing good for otherwise straight ammo.
The 6PPC is a better design across the board, though still poor IMO. And it's tiny.
If your 6PPC runout were normalized(extended) to 223/338LM length, it would suck also, but it would be better than the 338 and 223.
I'll give you an example of how to make & maintain straight ammo:
A good while ago I built a 26WSSM IMP in tight neck-fitted chamber. This is 1thou total clearance, everywhere, from new brass in-hand. The necks were turned to normal thickness & fitting. The throat was coaxial with 1/2thou total clearance of in-hand bullet bearing.
I did this as experimental.
To make ammo that would even chamber here, I first started with selecting cases with ~zero thickness variance(<.0001). I used a good neck mic to do this, and ended up with ~120 cases out of 1,000 in Win reloading brass. Then I moved into all other preps and fireformed the cases. Then I measured and selected those matching in H20 capacity, which took me down to ~80 cases.
Some would think this is bad, that Win reloading brass for WSSM is bad -they're wrong. Having measured other brass brands with other cartridges over the years I can tell you none are better.
My early loaded runout with this ammo was immeasurable(beneath surface profile). I could chamber rounds without so much as a scratch or rub spot visible on extraction to either cases or bullets.
But by the 9th reload cycle I was forced to bump 35deg shoulders. I knew this up front and don't know why I didn't go to 45, or even 60deg shoulders. Next chamber..
Anyway, even with bumping my TIR after ~40+ reloads(second barrel) on this same brass is still below 1thou measured off bullet ogives.
The reason TIR here is still so low, is that the cases have never been FL sized, and never been neck sized for that matter(only shoulder bumps). If I were to FL size, even once, my runout would take a step change that is forever ugly(to me). My H20 capacities would never match again either..
But I will never have to, due to design, and these cases will last the rest of my life.
That makes ~80 per 1,000 cases a **** good deal.
I know you can't do this with just any cartridge design. It needs to be an improved design. Nor can you do this without an actual plan.
I did it for the learning, and ended up very happy with the cartridge, to my surprise.
My accuracy load produces ~3030fps, ES ~8fps, with 139Laps out of 28" Border barrels.
Anyway(again), while your doing things differently with your ammo than I did above, notice how your results make perfect sense.
Remember what I said about the cause of runout earlier;
-Sizing/springback of thickness variance in cases
-Poor bullet seating
You're using Wilson inline seating, which helps a lot, but you're still FL sizing long cases.
The cartridges 223rem and 338LM are poor cartridge designs w/resp to making and maintaining straight ammo. They both hold low shoulder angles and high body taper, and they're long for diameter. With this, you have no choice but to FL size the 223, if using hot loads, and no choice at all about FL sizing with the 338 either way.
FL sizing moves brass. It brings springback into play. It does nothing good for otherwise straight ammo.
The 6PPC is a better design across the board, though still poor IMO. And it's tiny.
If your 6PPC runout were normalized(extended) to 223/338LM length, it would suck also, but it would be better than the 338 and 223.
I'll give you an example of how to make & maintain straight ammo:
A good while ago I built a 26WSSM IMP in tight neck-fitted chamber. This is 1thou total clearance, everywhere, from new brass in-hand. The necks were turned to normal thickness & fitting. The throat was coaxial with 1/2thou total clearance of in-hand bullet bearing.
I did this as experimental.
To make ammo that would even chamber here, I first started with selecting cases with ~zero thickness variance(<.0001). I used a good neck mic to do this, and ended up with ~120 cases out of 1,000 in Win reloading brass. Then I moved into all other preps and fireformed the cases. Then I measured and selected those matching in H20 capacity, which took me down to ~80 cases.
Some would think this is bad, that Win reloading brass for WSSM is bad -they're wrong. Having measured other brass brands with other cartridges over the years I can tell you none are better.
My early loaded runout with this ammo was immeasurable(beneath surface profile). I could chamber rounds without so much as a scratch or rub spot visible on extraction to either cases or bullets.
But by the 9th reload cycle I was forced to bump 35deg shoulders. I knew this up front and don't know why I didn't go to 45, or even 60deg shoulders. Next chamber..
Anyway, even with bumping my TIR after ~40+ reloads(second barrel) on this same brass is still below 1thou measured off bullet ogives.
The reason TIR here is still so low, is that the cases have never been FL sized, and never been neck sized for that matter(only shoulder bumps). If I were to FL size, even once, my runout would take a step change that is forever ugly(to me). My H20 capacities would never match again either..
But I will never have to, due to design, and these cases will last the rest of my life.
That makes ~80 per 1,000 cases a **** good deal.
I know you can't do this with just any cartridge design. It needs to be an improved design. Nor can you do this without an actual plan.
I did it for the learning, and ended up very happy with the cartridge, to my surprise.
My accuracy load produces ~3030fps, ES ~8fps, with 139Laps out of 28" Border barrels.
Anyway(again), while your doing things differently with your ammo than I did above, notice how your results make perfect sense.
