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Best concentricity sizing method I have used
- Thread starter hounddawg
- Start date
The 8 x 10 Shot, 100 yd NBRSA record is .1847 inch. Don't know the size of the biggest group. Quarter inch groups at 100 yards are common.I have never blamed anyone but myself for a bad shot . I win Benchrest at 100 and 200 yards , and I could never say I was 100 percent certain my equipment or loads have failed me . This of course is after fully working up a load and it proving itself in a match . I don't believe anyone can that actually touches that trigger without an artificial aid can say they are better than that load. Way too many variables involved, human error is something some folks just can't admit . This coming from a guy that hates it when a flier opens my group to .250" at 100 .
I don't think there are any fliers. Every shot fired goes where the system variables intended it to go. System includes rifle and what aims it, ammo, environment.
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@ Bart I like about 1.5 pounds on my F class triggers. My short range BR rifle is 2oz which to me is too sensitive. If all I shot was BR I could probably get used to it in time
@ Maxwell - I think of shooting as a tripod. Shooter, equipment, and ammo. Otherwise a person of your talent you could shoot sub .25 groups with a factory rifle and off the shelf ammo. BTW you must win a lot of matches or just be referring to 100 yard groups since the grand aggregates on short range group matches (100/200) typically run around .20 MOA and up
@ Maxwell - I think of shooting as a tripod. Shooter, equipment, and ammo. Otherwise a person of your talent you could shoot sub .25 groups with a factory rifle and off the shelf ammo. BTW you must win a lot of matches or just be referring to 100 yard groups since the grand aggregates on short range group matches (100/200) typically run around .20 MOA and up
Maxwell Haus
Moderator
Thanks for that,, but I know all about group size . I used quarter inch as an example . If I am in the 1s I am happy . Not sure what your point is .The 8 x 10 Shot, 100 yd NBRSA record is .1847 inch. Don't know the size of the biggest group. Quarter inch groups at 100 yards are common.
Maxwell Haus
Moderator
I am happy when I am in the 1s at 100 , 200 yard I shoot score mostly . Not trying to brag, just trying to point out a guy that can shoot can't be for certain 100 percent that his equipment failed him on small groups unless there was some type of obvious failure . If I am in the 1,s all match then I get one out of the group I can be certain I was involved . Sometimes I get distracted and my mind wanders , sometimes I am having a bad eye day, sometimes my finger is cold and can't tell when the 2 ounce trigger will break. All human error.@ Bart I like about 1.5 pounds on my F class triggers. My short range BR rifle is 2oz which to me is too sensitive. If all I shot was BR I could probably get used to it in time
@ Maxwell - I think of shooting as a tripod. Shooter, equipment, and ammo. Otherwise a person of your talent you could shoot sub .25 groups with a factory rifle and off the shelf ammo. BTW you must win a lot of matches or just be referring to 100 yard groups since the grand aggregates on short range group matches (100/200) typically run around .20 MOA and up
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.
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.
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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.
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.
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"
Never heard of sizing with the die loose.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.
I'd never do that.
Tighten the die then get under .001" consistency.
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?
"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?
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.
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.
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?
Perhaps I misunderstood.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?
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.
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.
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
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 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.
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.