5-Shot Test Group's Size and Shapes

[jhop28]

Kevin you hit the nail that's why Palma guys won't talk to us it's a spindle thing

 

[Bart B.]

Do you still shoot?

No. Physical and visual issues that us past 75 sometimes have; small but enough to impair performance.

 

[fyrewall]

All the above is informative - I have not competed in a shooting event for 49 years. I find it amazing so see such incredible accuracy and skill as shown by the 1,000 yard targets with tea saucer size groups. I would carefully avoid making comments about this stuff being intimidated by the level of performance shown except that some of my targets look like the ones shown. No doubt thread participants have analyzed their equipment and techniques extensively meaning nothing is excluded. I only reject stuff that is contrary to laws of physics & chemistry.

I have found the techniques shown by the attached to be useful for my informal use for shooting steel targets & rodents

optimalchargeweight.embarqspace.com/ocw-vs-ladder/4529811360

 

[Bart B.]

I have found the techniques shown by the attached to be useful for my informal use for shooting steel targets & rodents

optimalchargeweight.embarqspace.com/ocw-vs-ladder/4529811360

I don't think that OCW method's explanations as to how it works is reality.

As good lots of Federal match ammo shoots well under MOA short range groups across good quality barrel lengths from 22 to 28 inches and barrel times varying a lot due to bore and groove dimensions, there is no way that shock wave will not be at the muzzle all the time when the bullet's exit. That shock wave makes several round trips in the barrel before bullets exit. And the speed that wave travels in steel as stated is different that what most mechanical engineers dealing with metal properties list. Nowhere in the OCW method text does it mention where in the barrel that shock wave begins which means timing it with bullet barrel time is not precisely determined

All the Garand barrels I wore out had the muzzle bore and groove diameters belled out a couple thousandths inch from cleaning rod wear; no copper wash the last 2/3rds inch of the barrrel. They still tested sub MOA through 300 yards with commercial match ammo.

I've known people who set their 28 inch match rifle 308 Win barrel back 2 inches every 2000 rounds and get the same sub MOA accuracy through 1000 yards with the same load with all barrel lengths.

I've shot the same 308 Win Federal match ammo through 22" M14NM barrels, 24" Garand barrels and 26 and 28 inch match rifle barrels testing through 300 yards. All 10-shot test groups were under 3/4 MOA.

To me, it works because the load puts bullets out the barrel in an optimal range of muzzle axis whip in the vertical axis; typically somewhere on the up swing. Doesn't matter how many millionths of an inch the muzzle diameters change to when bullets exit.

 

[Heman]

Found this article that was here on this very website.

http://bulletin.accurateshooter.com/tag/7mm/

 

[fyrewall]

I don't think that OCW method's explanations as to how it works is reality.

As good lots of Federal match ammo shoots well under MOA short range groups across good quality barrel lengths from 22 to 28 inches and barrel times varying a lot due to bore and groove dimensions, there is no way that shock wave will not be at the muzzle all the time when the bullet's exit. That shock wave makes several round trips in the barrel before bullets exit. And the speed that wave travels in steel as stated is different that what most mechanical engineers dealing with metal properties list. Nowhere in the OCW method text does it mention where in the barrel that shock wave begins which means timing it with bullet barrel time is not precisely determined

All the Garand barrels I wore out had the muzzle bore and groove diameters belled out a couple thousandths inch from cleaning rod wear; no copper wash the last 2/3rds inch of the barrrel. They still tested sub MOA through 300 yards with commercial match ammo.

I've known people who set their 28 inch match rifle 308 Win barrel back 2 inches every 2000 rounds and get the same sub MOA accuracy through 1000 yards with the same load with all barrel lengths.

I've shot the same 308 Win Federal match ammo through 22" M14NM barrels, 24" Garand barrels and 26 and 28 inch match rifle barrels testing through 300 yards. All 10-shot test groups were under 3/4 MOA.

To me, it works because the load puts bullets out the barrel in an optimal range of muzzle axis whip in the vertical axis; typically somewhere on the up swing. Doesn't matter how many millionths of an inch the muzzle diameters change to when bullets exit.

***************

Just when I thought I had this stuff sort of under control I was hit with a wave of confusion.

From the OCW stuff regarding shock wave --- "The shock wave as identified and described by engineer Chris Long in the page listed above is at the muzzle when these bullets are being released"

the "page listed above" appears in the OCW article

from Bart B -----"...,there is no way that shock wave will not be at the muzzle all the time when the bullet's exit."

Possibly, the difference might be, "as identified and described" in regard to shock wave effects.

Generally I like the idea of using larger powder charge increments vs. nibbling away at some goal with .1 to .3 grain increments beginning at a recommended start level that in the example shown is about 7% less than maximum loads. Just think how many test events that would be fired going from a recommended start load of 43 grains to a maximum load of 46 grains (46-43)/.2 = 15 loads using a .2 grain increment (Hodgdon manual .308 Win, 155 Sierra MK, H4895 powder). Three shots @ each load increment = 3 * 15 = 45.

Also, when shooting a bunch of bullets like up to 20 or so at a target that might be 300 yards out stuff can happen like your body might get tired, the barrel might foul up, wind can change and so on. The OCW article gets into the "round robin (bird?) firing sequence where up to 5 different targets are used with moderate charge increments, like up to .4 grains. Targets are then fired on in sequence with 1st load, 2nd load, 3rd load, 4th load, and finally 5th load, then the sequence is repeated four more times - each target shot with same load. The idea is to spread any screw-ups equally among target groups vs having one or possible a minor amount more screw up (affect) the whole works.

Another thing I like about the OCW approach is that individual clusters of data vs. large data groups are considered.

Upon closing, my experiences with the Garand were terrible in comparison to Bart's and I attribute that to my being usually issued a "beater" rifle. I see diversion from the original intent of the OCW idea with a discussion of issued ammo produced in giant factories in lots of 1000's and vibrating barrels that shoot bullets/loads that have been proven to be accurate.

 

[dmoran]

Lots of folks don't understand why several 5-shot groups across two days of benchrest matches with the same rifle:

* are not the same size, but have a 5 to 6 times spread from smallest to largest.
* don't have all group centers the same place relative to aim point.
* shoot the smallest one first in match 1. Largest one either, for that matter.

According to mechanical engineers in mass vibration analysis, most of the muzzle axis vibration is in the vertical plane. That's because the recoil axis is mostly directly above the rifles center of mass. Which is why tuner weights' position change the vibration frequency just enough to let bullets exit at the best place for accuracy.

If you ever look at the 5-shot group results of a benchrest match, each competitors' groups easily have up to a 6X or more spread in size.
http://forum.accurateshooter.com/threads/fed-v-win-brass-accuracy-difference-with-pics.3945430/

@Bart B.
Knowing that your "spread" inputs to Benchrest are grossly in error, or outdated by a great many years/decades, and since you have repeatedly posted this misinformation many times here and on other shooting related forums, feel it is time you correct your error and false implications (at the least, from this day forward). And strongly suggest you research into modern day Benchrest, before making any future implications or comparisons to it.

Attaching below "spread data" to all the participants results from this years 2018 Cactus Classic.
Here is stats from the spread data in the attachment:

• Spread Average: 2.22 X
• Best Spread: 1.1 X
• Worse Spread: 9.6 X
• Count of 5X or more: 5 (less then 1% of all the participants)
• Class finishing positions of the 5: 1st / 33rd / 129th / 133rd / 136th

From these stats, as well as from other Benchrest discipline stats (600/1000 BR), the fact is that 5 and 6X spreads are a rarity, and make up a very small percentage (less then 1% to many BR matches).

The 2.22 X spread average from this years Cactus, is statistically similar of all Benchrest currently.
My own 1000-BR career spread stats from all the targets I've shot over 14-years, "the best to the worse" being 4.93 X for HV-Gun (10-shots), and 6.67 X for LT-Gun (5-shots).
Donovan

 

[ClassCat]

View attachment 1032650 Here are five. The charge weight varied thru the day. Don't remember right off by how much. Wasn't a lot
This gun and barrel is a shooter. You still have to pull the trigger at the right time tho
They don't magically all print at the same poa

A 142 AGG,, Impressive ! Now tell them How to Read the WIND. My BAD, That comes with Experience,which you have. Where did you shoot that ?

 

[Bart B.]

For those who don't understand, or realize, or comprehend that "up to a 6X spread" includes a 1.001 X spread and all other increments of any multiple up to and including a 6.000 X spread, I cannot help you grasp reality.

 

[jimmymac]

View attachment 1032650 Here are five. The charge weight varied thru the day. Don't remember right off by how much. Wasn't a lot
This gun and barrel is a shooter. You still have to pull the trigger at the right time tho
They don't magically all print at the same poa

That's awesome Tim. Hope to be able to do that one of these days.

 

[ClassCat]

For those who don't understand, or realize, or comprehend that "up to a 6X spread" includes a 1.001 X spread and all other increments of any multiple up to and including a 6.000 X spread, i cannot help you grasp reality.

Can you put that in English for a simple Benchrest shooter ( ME)

 

[Bart B.]

Can you put that in English for a simple Benchrest shooter ( ME)

I'll try.

There are five 1 inch increments from 1 inch to 6 inches.

6 is six times bigger than 1.

6 is six thousand times bigger than .001.

Divide any group by the smallest one shot.

 

[ClassCat]

I'll try.

There are five 1 inch increments from 1 inch to 6 inches.

6 is six times bigger than 1.

6 is a six thousand times bigger than .001.

Our disciplines are different,You're score shooting, Our score is based on same hole accuarcy

 

[dmoran]

@ClassCat
Just his way of paraphrasing a new meaning other then what he has actually been saying.
Donovan

 

[Tim Singleton]

A 142 AGG,, Impressive ! Now tell them How to Read the WIND. My BAD, That comes with Experience,which you have. Where did you shoot that ?

Riverbend GA. SE regional 2017

 

[Bart B.]

I never said all groups had a 6X spread in size.

"...up to 6X" includes those between a 1X and any other multiple up to 6X.

 

[Toby Bradshaw]

I never said all groups had a 6X spread in size.

"...up to 6X" includes those between a 1X and any other multiple up to 6X.

Your quote from post #5 in this thread (before you edit it again):

Lots of folks don't understand why several 5-shot groups across two days of benchrest matches with the same rifle:

* are not the same size, but have a 5 to 6 times spread from smallest to largest.

You said "5 to 6 times", not "up to 5 or 6 times" or "1 to 6 times". Own it.

 

[dmoran]

@Toby Bradshaw
And in the other thread, he wrote it like this:

If you ever look at the 5-shot group results of a benchrest match, each competitors' groups easily have up to a 6X or more spread in size.

Post #13
http://forum.accurateshooter.com/threads/fed-v-win-brass-accuracy-difference-with-pics.3945430/

 

[Toby Bradshaw]

@Toby Bradshaw
And in the other thread, he wrote it like this:



Post #13
http://forum.accurateshooter.com/threads/fed-v-win-brass-accuracy-difference-with-pics.3945430/

 

[Bart B.]

I said "most" or "some" or "up to".....

Show me where I specifically said "all groups" without any other bandwidth.