Best concentricity sizing method I have used - Page 2

hounddawg · February 25, 2021, 10:48 AM

yep 1/4 inch groups at 100 yard BR matches is common. That said most 5 round top five aggregates are in the .2's. However in short range BR most matches are conducted at 100 and 200 and sub .25 groups are not common at that 200 range. In fact .5 groups are not that common.

In NRA F class a 1 MOA 20 round group centered would be a clean 200 and even those are not all that common. High Master rating is given when you shoot 98% of 120 consecutive match shots into a 1 MOA 10 ring. I am running 97.5 % now, so close but yet so far. There are only about 600 or so F class HM's in the USA. Once you start factoring in longer ranges and increased numbers of shots the difficulty of getting that .25 MOA group goes way up.

Nathan · February 26, 2021, 02:21 PM

I like the squaring washer idea. Any idea where I can get a squaring washer or parallel flat surface?

Bart B. · February 26, 2021, 03:32 PM

The flat top of the press is square with the female thread axis where the die goes. All the washer does is take up space.

Nathan · February 26, 2021, 04:42 PM

Yes, but is any washer flat enough for this or how do I get a flat enough one?

zeke · February 26, 2021, 04:44 PM

Nathan-Am only using a washer for seating dies. Bought from local harware store. For rifle/pistol brass am loosening lock ring when adjusting die for amount of sizing on piece of brass. This squares up the actual part of the die that does the sizing with the brass on bottom of cut out in shell holder.

Learned this after finding out the carbide insert in one pistol die was off kilter enough to see the results in pistol brass. As i do not have personal experience with every single press ever manufactured, can not remark on how well they are manufactured.

Nathan · February 26, 2021, 04:46 PM

BTW, I basically do this. I size a case with the die loose. Then with handle pressure on that case, I tightened the lock ring. I can get under 0.002” consistently with Forster FL dies and neck turned brass.

How is your bullet concentricity coming out?

zeke · February 26, 2021, 04:56 PM

For rifle rounds am using highly sophisticated method of rolling round on flat piece of glass/marble. Pretty easy to see any bullet wobble. Most rounds have no discernible wobble, largely due to the Redding comp seating die. Pick a round with .002 bullet run out. Roll it across hard flat surface at eye level. While not usually a betting man, bet you see an obvious "wobble"

Bart B. · February 26, 2021, 05:54 PM

Quote:

Originally Posted by Nathan

BTW, I basically do this. I size a case with the die loose. Then with handle pressure on that case, I tightened the lock ring. I can get under 0.002” consistently with Forster FL dies and neck turned brass.

Never heard of sizing with the die loose.

I'd never do that.

Tighten the die then get under .001" consistency.

zeke · February 26, 2021, 06:08 PM

Apparently it may be difficult to understand that this process is used to square up the die, before it is locked down for all the cases being sized.

"Then with handle pressure on that case, I tightened the lock ring"

Personally am having difficulty understanding how anyone could interpret this as "sizing with the die loose" unless you are interpreting the die is then loosened again, and process repeated for every single case?

HiBC · February 26, 2021, 06:59 PM

Flat ground hardened machine washers are available. Try E-bay.

The question "How do you measure it?" is interesting.The definition of concentric is sharing the same center point or axis.

How do you establish the center point or axis of a loaded cartridge?
You can't put it between centers to establish an axis.

Vee blocks,or rollers? Is roundness considered? Concentricity or coaxiality?

Is straightness considered? Cartridge head and neck? Neck wall thickness? Neck straightness? Or work off the case head and the bullet?

Whatever works for you,but if you get real technical,whatever guage you have might give you a useful number...OK,fine.Close enough!

But to give you true measurements,you might need a co-ordinate measuring machine,or you might need to establish Datums. Theoretical circles or cylinders, and those might be represented by a precision collet,or it could be a a center with a throat or bore dia to engage the bullet ogive.

No doubt Sinclair or Hornady,etc will sell you very nice tools with indicators and they are useful.

But its unlikely you can measure "Concentricity" per ASME Y 14.5 Geometric Dimensioning and Tolerancing unless ,for example a datum diameter and location is established at the case head and perhaps another datum diameter to represent rifling engagement to the ogive,then a T.I.R. spec perhaps at the shoulder datum diameter or .100 behind the shoulder....
The minimum/maximum material condition come into play as does the chamber dimensions ...cartridge/ chamber clearance...

IF what you are trying to control is the bullet being coaxial to the bore at ignition. Or obturation??

Enjoy what you are doing,make good,straigt ammo...Happy shooting!

Just realize the statement "My ammo is concentric to .002 " is a pretty complex statement...and subject to review.

hounddawg · February 26, 2021, 08:12 PM

it's all relative, just as the term accuracy may be defined differently by a benchrest shooter, a F class shooter and a hunter. When I speak in terms of concentricity on a reloading forum I what am referring to is the bullet concentric (parallel) to the case body. Or as you put it does the mepalt of the bullet share the same center point as the web of the case. But we all knew that didn't we?

Bart B. · February 26, 2021, 08:55 PM

Quote:

Originally Posted by zeke

Apparently it may be difficult to understand that this process is used to square up the die, before it is locked down for all the cases being sized.

"Then with handle pressure on that case, I tightened the lock ring"

Personally am having difficulty understanding how anyone could interpret this as "sizing with the die loose" unless you are interpreting the die is then loosened again, and process repeated for every single case?

Perhaps I misunderstood.

HiBC · February 26, 2021, 09:14 PM

When the die is under full load,The surface it is mating to is the thread forms of the 60 deg vee threads.

The lock ring on the machined top of the press may or may not have full tight contact with the press.

An O-ring sustains a moderate,floatable preload on the threads,and anti-rotation friction.

The Bonanza/Forster CoAx press has a reputation for straight/concentric ammo.

No 7/8 - 14 threads. The lock ring drops in a slot. The die can float.

IMO,the Forster die expander spindle is superior.

I cannot say I've done testing. Its opinion. I'll point that out.

hounddawg · February 26, 2021, 11:24 PM

and of course the cse floats in the shellholder, quite a bit actually. I measured it once on one of these discussions. Best I can remember it was .003 - .005 on the Y axis and .010 on the X axis or something close to that.

Regardless, when the case is inserted in a full length die there is no wiggle room anywhere. The dies are cut with one piece reamers so at the point in time when case is at top dead center in the die the neck is as parallel to the case body as it is going to get. It may or may not be concentric with the bit of the case web that is outside the die and it may or may not be perpendicular to the case head but it will be concentric with the case body that is inserted into the die. If that neck gets bent it gets bent when the case is being withdrawn from the die and the neck and case body are no longer supported by the walls of the die

Bart B. · February 27, 2021, 12:44 AM

How do you establish the center point or axis of a loaded cartridge?

It's easy and simple for cartridges headspacing on their shoulder. When fired, the case shoulder is pressed and well centered in the chamber shoulder. A perfectly straight cartridge has its head pressed off center by the extractor a thousandths or two against the chamber. Bullet tip is off bore center in the opposite direction about half as much as the case head.

hounddawg · February 27, 2021, 01:56 AM

as long as we are asking questions no one can really answer

- at what point in the bullets travel has the case expanded to the point where there is zero clearance between the case and the chamber walls ?

- just to use made up numbers lets presume the case is .001 smaller than the camber and sitting on the bottom of the chamber with the bullet angled up at at a angle of .001 degrees. Would not it be better to have the concentricity of the bullet as close to 0 as possible so the that the bullet is always exiting the cartridge at the same angle every firing?

- would not a target barrel have less clearance between the cartridge and the chamber than a M1 surplus with the original barrel ?

HiBC · February 27, 2021, 11:55 AM

OK,here is another variable Bart has often mentioned.Bolt face squareness,cartridge head squareness. Either out of square you have the leaning tower of Piza.

Something I never did,just an imaginary solution to a problem that may not exist...
Alter a belted magnum chambering reamer so the belt face and its seat in the chamber are matching 45 degrees. The belt would seat in the chamber like a valve in a cylinder head in an engine.
The cases would have to be altered with a lathe and collet.Head clearance held close to zero.
That should center the case head in the chamber.If the shoulder centers ,the cartridge would theoretically be between centers,

hounddawg · February 27, 2021, 12:17 PM

fine stuff for a winters day discussion over a adult beverage in front of a warm fire but nothing but pure speculation. Maxwell pointed out above tiny tiny groups are shot on a regular basis at 100 yards with things just as they are. There has to be clearance between the case body and neck and the chamber, that's a given. How the bolt and extractor hold the case when the bolt is enclosed be it at a angle or parallel to the bore I cannot change and my XRay vision is out for repair so I won't even bother speculating on.

What I can do is make sure that the bullet is a parallel to the case as I can make it, that my bolt face is square and my technique is solid. That and pray to the gods of wind and mirage not to put a unseen gust of crosswind at 600 yards by sacrificing thousands of round in practice

Bart B. · February 27, 2021, 01:38 PM

It's easy to see all the spring loaded parts of the action that push the cartridge that's in the chamber.

Check them out in your rifle; magazine, firing pin, extractor and bolt face ejector.

Maxwell Haus · February 27, 2021, 02:07 PM

I keep it simple ,no ejector and size my brass to a light "crush" fit . Some bullets are jammed, so that helps . If things were very crooked they just just got as straight as my chamber when I closed the bolt.

Bart B. · February 27, 2021, 02:41 PM

Quote:

Originally Posted by Maxwell Haus

I keep it simple ,no ejector and size my brass to a light "crush" fit . Some bullets are jammed, so that helps . If things were very crooked they just just got as straight as my chamber when I closed the bolt.

Doesn't the extractor claw against the case push the case body pressure ring off center against the chamber?

When neck only resizing was popular in the early 1960's, when the bolt was a small crush fit, accuracy got worse. Full length sizing setting the case shoulder back a couple thousandths fixed it for a few more neck only resizing routines.

The bolt goes into battery repeatable from shot to shot when nothing binds it up.

Maxwell Haus · February 27, 2021, 03:52 PM

Quote:

Originally Posted by Bart B.

Doesn't the extractor claw against the case push the case body pressure ring off center against the chamber?

When neck only resizing was popular in the early 1960's, when the bolt was a small crush fit, accuracy got worse. Full length sizing setting the case shoulder back a couple thousandths fixed it for a few more neck only resizing routines.

The bolt goes into battery repeatable from shot to shot when nothing binds it up.

Sorry, I am bored with this . You win . You don't even know what rifle I am talking about , you sure do like to debate.

Bart B. · February 27, 2021, 04:48 PM

Quote:

Originally Posted by Maxwell Haus

Sorry, I am bored with this . You win . You don't even know what rifle I am talking about , you sure do like to debate.

Apologies for upsetting you. I used to think like you are. Then the match winners and record setters straightened me out. I wanted to pass good stuff on to you.

Bart B. · February 28, 2021, 10:24 AM

Quote:

How the bolt and extractor hold the case when the bolt is enclosed be it at a angle or parallel to the bore I cannot change and my XRay vision is out for repair so I won't even bother speculating on.

Cartridge cases headspacing on their shoulder don't lay in the chamber bottom when fired. There's one or two spring loaded parts in the bolt that raise the case off the chamber bottom before firing.

hounddawg · February 28, 2021, 10:58 AM

Quote:

There's one or two spring loaded parts in the bolt that raise the case off the chamber bottom before firing.

isn't that pretty much what I said? I have to agree with Maxwell, you sure like to debate, even when there is no one disagreeing. Reminds me a lot of another poster who disappeared from here

I am going to go out on a limb here Bart and state that I bet most of the readers of this forum are aware of how a bolt works. Just speaking for myself I would rather spend my effort on things I can control rather than things I cannot

February 25, 2021, 10:48 AM	#26
hounddawg Senior Member Join Date: March 1, 2009 Posts: 4,232	yep 1/4 inch groups at 100 yard BR matches is common. That said most 5 round top five aggregates are in the .2's. However in short range BR most matches are conducted at 100 and 200 and sub .25 groups are not common at that 200 range. In fact .5 groups are not that common. In NRA F class a 1 MOA 20 round group centered would be a clean 200 and even those are not all that common. High Master rating is given when you shoot 98% of 120 consecutive match shots into a 1 MOA 10 ring. I am running 97.5 % now, so close but yet so far. There are only about 600 or so F class HM's in the USA. Once you start factoring in longer ranges and increased numbers of shots the difficulty of getting that .25 MOA group goes way up. __________________ “How do I get to the next level?” Well, you get to the next level by being the first one on the range and the last one to leave.” – Jerry Miculek Last edited by hounddawg; February 25, 2021 at 10:55 AM.

February 26, 2021, 08:12 PM	#36
hounddawg Senior Member Join Date: March 1, 2009 Posts: 4,232	it's all relative, just as the term accuracy may be defined differently by a benchrest shooter, a F class shooter and a hunter. When I speak in terms of concentricity on a reloading forum I what am referring to is the bullet concentric (parallel) to the case body. Or as you put it does the mepalt of the bullet share the same center point as the web of the case. But we all knew that didn't we? __________________ “How do I get to the next level?” Well, you get to the next level by being the first one on the range and the last one to leave.” – Jerry Miculek

February 26, 2021, 11:24 PM	#39
hounddawg Senior Member Join Date: March 1, 2009 Posts: 4,232	and of course the cse floats in the shellholder, quite a bit actually. I measured it once on one of these discussions. Best I can remember it was .003 - .005 on the Y axis and .010 on the X axis or something close to that. Regardless, when the case is inserted in a full length die there is no wiggle room anywhere. The dies are cut with one piece reamers so at the point in time when case is at top dead center in the die the neck is as parallel to the case body as it is going to get. It may or may not be concentric with the bit of the case web that is outside the die and it may or may not be perpendicular to the case head but it will be concentric with the case body that is inserted into the die. If that neck gets bent it gets bent when the case is being withdrawn from the die and the neck and case body are no longer supported by the walls of the die __________________ “How do I get to the next level?” Well, you get to the next level by being the first one on the range and the last one to leave.” – Jerry Miculek

February 27, 2021, 01:56 AM	#41
hounddawg Senior Member Join Date: March 1, 2009 Posts: 4,232	as long as we are asking questions no one can really answer - at what point in the bullets travel has the case expanded to the point where there is zero clearance between the case and the chamber walls ? - just to use made up numbers lets presume the case is .001 smaller than the camber and sitting on the bottom of the chamber with the bullet angled up at at a angle of .001 degrees. Would not it be better to have the concentricity of the bullet as close to 0 as possible so the that the bullet is always exiting the cartridge at the same angle every firing? - would not a target barrel have less clearance between the cartridge and the chamber than a M1 surplus with the original barrel ? __________________ “How do I get to the next level?” Well, you get to the next level by being the first one on the range and the last one to leave.” – Jerry Miculek

February 27, 2021, 12:17 PM	#43
hounddawg Senior Member Join Date: March 1, 2009 Posts: 4,232	fine stuff for a winters day discussion over a adult beverage in front of a warm fire but nothing but pure speculation. Maxwell pointed out above tiny tiny groups are shot on a regular basis at 100 yards with things just as they are. There has to be clearance between the case body and neck and the chamber, that's a given. How the bolt and extractor hold the case when the bolt is enclosed be it at a angle or parallel to the bore I cannot change and my XRay vision is out for repair so I won't even bother speculating on. What I can do is make sure that the bullet is a parallel to the case as I can make it, that my bolt face is square and my technique is solid. That and pray to the gods of wind and mirage not to put a unseen gust of crosswind at 600 yards by sacrificing thousands of round in practice __________________ “How do I get to the next level?” Well, you get to the next level by being the first one on the range and the last one to leave.” – Jerry Miculek

February 26, 2021, 02:21 PM	#27
Nathan Senior Member Join Date: July 1, 2001 Posts: 6,807	I like the squaring washer idea. Any idea where I can get a squaring washer or parallel flat surface?

February 26, 2021, 03:32 PM	#28
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	The flat top of the press is square with the female thread axis where the die goes. All the washer does is take up space.

February 26, 2021, 04:42 PM	#29
Nathan Senior Member Join Date: July 1, 2001 Posts: 6,807	Yes, but is any washer flat enough for this or how do I get a flat enough one?

February 26, 2021, 04:44 PM	#30
zeke Senior Member Join Date: November 17, 1999 Location: NW Wi Posts: 1,759	Nathan-Am only using a washer for seating dies. Bought from local harware store. For rifle/pistol brass am loosening lock ring when adjusting die for amount of sizing on piece of brass. This squares up the actual part of the die that does the sizing with the brass on bottom of cut out in shell holder. Learned this after finding out the carbide insert in one pistol die was off kilter enough to see the results in pistol brass. As i do not have personal experience with every single press ever manufactured, can not remark on how well they are manufactured.

February 26, 2021, 04:46 PM	#31
Nathan Senior Member Join Date: July 1, 2001 Posts: 6,807	BTW, I basically do this. I size a case with the die loose. Then with handle pressure on that case, I tightened the lock ring. I can get under 0.002” consistently with Forster FL dies and neck turned brass. How is your bullet concentricity coming out?

February 26, 2021, 04:56 PM	#32
zeke Senior Member Join Date: November 17, 1999 Location: NW Wi Posts: 1,759	For rifle rounds am using highly sophisticated method of rolling round on flat piece of glass/marble. Pretty easy to see any bullet wobble. Most rounds have no discernible wobble, largely due to the Redding comp seating die. Pick a round with .002 bullet run out. Roll it across hard flat surface at eye level. While not usually a betting man, bet you see an obvious "wobble"

February 26, 2021, 06:08 PM	#34
zeke Senior Member Join Date: November 17, 1999 Location: NW Wi Posts: 1,759	Apparently it may be difficult to understand that this process is used to square up the die, before it is locked down for all the cases being sized. "Then with handle pressure on that case, I tightened the lock ring" Personally am having difficulty understanding how anyone could interpret this as "sizing with the die loose" unless you are interpreting the die is then loosened again, and process repeated for every single case?

February 26, 2021, 06:59 PM	#35
HiBC Senior Member Join Date: November 13, 2006 Posts: 8,350	Flat ground hardened machine washers are available. Try E-bay. The question "How do you measure it?" is interesting.The definition of concentric is sharing the same center point or axis. How do you establish the center point or axis of a loaded cartridge? You can't put it between centers to establish an axis. Vee blocks,or rollers? Is roundness considered? Concentricity or coaxiality? Is straightness considered? Cartridge head and neck? Neck wall thickness? Neck straightness? Or work off the case head and the bullet? Whatever works for you,but if you get real technical,whatever guage you have might give you a useful number...OK,fine.Close enough! But to give you true measurements,you might need a co-ordinate measuring machine,or you might need to establish Datums. Theoretical circles or cylinders, and those might be represented by a precision collet,or it could be a a center with a throat or bore dia to engage the bullet ogive. No doubt Sinclair or Hornady,etc will sell you very nice tools with indicators and they are useful. But its unlikely you can measure "Concentricity" per ASME Y 14.5 Geometric Dimensioning and Tolerancing unless ,for example a datum diameter and location is established at the case head and perhaps another datum diameter to represent rifling engagement to the ogive,then a T.I.R. spec perhaps at the shoulder datum diameter or .100 behind the shoulder.... The minimum/maximum material condition come into play as does the chamber dimensions ...cartridge/ chamber clearance... IF what you are trying to control is the bullet being coaxial to the bore at ignition. Or obturation?? Enjoy what you are doing,make good,straigt ammo...Happy shooting! Just realize the statement "My ammo is concentric to .002 " is a pretty complex statement...and subject to review.

February 26, 2021, 09:14 PM	#38
HiBC Senior Member Join Date: November 13, 2006 Posts: 8,350	When the die is under full load,The surface it is mating to is the thread forms of the 60 deg vee threads. The lock ring on the machined top of the press may or may not have full tight contact with the press. An O-ring sustains a moderate,floatable preload on the threads,and anti-rotation friction. The Bonanza/Forster CoAx press has a reputation for straight/concentric ammo. No 7/8 - 14 threads. The lock ring drops in a slot. The die can float. IMO,the Forster die expander spindle is superior. I cannot say I've done testing. Its opinion. I'll point that out.

February 27, 2021, 12:44 AM	#40
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	How do you establish the center point or axis of a loaded cartridge? It's easy and simple for cartridges headspacing on their shoulder. When fired, the case shoulder is pressed and well centered in the chamber shoulder. A perfectly straight cartridge has its head pressed off center by the extractor a thousandths or two against the chamber. Bullet tip is off bore center in the opposite direction about half as much as the case head.

February 27, 2021, 11:55 AM	#42
HiBC Senior Member Join Date: November 13, 2006 Posts: 8,350	OK,here is another variable Bart has often mentioned.Bolt face squareness,cartridge head squareness. Either out of square you have the leaning tower of Piza. Something I never did,just an imaginary solution to a problem that may not exist... Alter a belted magnum chambering reamer so the belt face and its seat in the chamber are matching 45 degrees. The belt would seat in the chamber like a valve in a cylinder head in an engine. The cases would have to be altered with a lathe and collet.Head clearance held close to zero. That should center the case head in the chamber.If the shoulder centers ,the cartridge would theoretically be between centers,

February 27, 2021, 01:38 PM	#44
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	It's easy to see all the spring loaded parts of the action that push the cartridge that's in the chamber. Check them out in your rifle; magazine, firing pin, extractor and bolt face ejector.

February 27, 2021, 02:07 PM	#45
Maxwell Haus member Join Date: December 14, 2016 Posts: 113	I keep it simple ,no ejector and size my brass to a light "crush" fit . Some bullets are jammed, so that helps . If things were very crooked they just just got as straight as my chamber when I closed the bolt.