CAST .22 BULLET ACCURACY VARIES WIDELY, DAY TO DAY

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joeb33050 posted this 21 January 2017

Cast 22 bullet accuracy varies a lot from day to day. Savage Striker 22-250, 225646M, SR4756, 8.0 gr, 5 shots 100 yards “ 

4/25/16---.250, 1.1, .850; avg 1.067 

12/2/15---1.25, 1.6, 1.4, 1.05, .85, avg 1.23 

2/29/16---1.5, 1.15, .7, 1.6, 1.2; avg 1.23 

5/4/16---1.6, .95; avg 1.275 

3/5/16---1.75, 1.25, 1.6, .95, 1.85; avg 1.48 

3/3/16---2, 1.175, 3, 1.875, 1.6; avg 1.93 

The average for the 25 groups above is 1.404” 

1/20/17---The first 9 shots were all over the paper, no detectable groups. 

I have tried to find the reason for this variation, and so far it escapes me. There are many other examples.

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max503 posted this 21 January 2017

I'm just wondering if it has something to do with the amount of fouling or residual lube in the bore.

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99 Strajght posted this 21 January 2017

Sometime with cast bullets I have found the same thing. The amount of time from between when I reload and shoot sometime can cause different  accuracy. I think it could be neck tension. I think the bullet might adhere to the case. I have also seem it with jacketed bullets.   Glenn

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OU812 posted this 21 January 2017

Aging of cast bullets has an effect on bullet hardness and accuracy. Pressure should match alloy hardness. I am now letting my cast bullets age at least 2 weeks before testing to see if this helps.

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frnkeore posted this 21 January 2017

I note that you've been doing low velocity jacketed testing. 

Did you get the jacketed fouling out, before going back to cast?

Frank

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joeb33050 posted this 21 January 2017

I note that you've been doing low velocity jacketed testing. 

Did you get the jacketed fouling out, before going back to cast?

Frank

I shoot the cast first, in a clean barrel.

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joeb33050 posted this 22 January 2017

I note that you've been doing low velocity jacketed testing. 

Did you get the jacketed fouling out, before going back to cast?

Frank

I shoot the cast first, in a clean barrel. After 9 cast and 30 jacketed bullets the barrel cleaned easily and fast. With Hoppes #9 left in the barrel, 4 times, left to work for a few hours, there was a little green on the 4 patches. The next few patches showed no green. I'm looking for copper fouling, and finding very little, frequently none. This at low velocities.

joe b.

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frnkeore posted this 22 January 2017

Try some Sweets or another that's made specficly for copper, just to make sure.

 

Frank

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onondaga posted this 22 January 2017

Joe, you won't change results unless you make a major change in something and evaluate just that change. Try something completely different that works for me and is something that you show no interest in.. Get a Hoppe's BoreSnake and use nothing else for the test, Pull it through 3 times on a dirty rifle before you start a string, then pull it through once every 5 shots, Use nothing on the BoreSnake, no solvents or oil. Just use it clean and dry.  This routine maintains relatively constant bore condition. It is not immaculate and that is the point.  Your starting from an immaculate bore leaves a bore that quickly changes. The changing bore conditions from starting with an immaculate bore stinks for maintaining relative consistent bore condition.

http://www.midwayusa.com/product/260083/hoppes-boresnake-bore-cleaner-rifle

 

Gary

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onondaga posted this 25 January 2017

Joe, are you speechless and in shock at my recommendation? Or, have you ordered a BoreSnake?

 

Gary

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joeb33050 posted this 25 January 2017

Joe, are you speechless and in shock at my recommendation? Or, have you ordered a BoreSnake?

 

Gary

 

Gary;

I'm not in shock and never speechless. After shooting 9 cbs all over the paper, the next 5 jacketed bullets shot into an average of .905". It wasn't bore condition. I know you love the bore snake, and I hope you are very happy.

joe b.

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HuskerP7M8 posted this 25 January 2017

 

Hi Joe, 

 

After I read your post and looked at the group ES (Extreme Spread) for the 25 groups you shot, it didn't appear to me that the variation in ES was abnormal. Since I was curious, I decided to conduct a very simple check to possibly verify if your group sizes and group size averages varied more than we would expect to see. 

 

Are you familiar with the term COV (Coefficient Of Variation)? 

 

Again, to keep this very simple, for those who aren't statistical nerds like me, the COV varies based on the number of shots used to form each group.

It's an easy calculation that's nothing more than the Standard Deviation divided by the Average, and if you use Excel, format the cell which contains the formula as a percentage. The end result is a percentage that tells you how much variation, on average, you can expect to see when shooting a string of groups. 

 

In your case, using 5-shot groups, the COV should be approximately 25%.

If you had used 2-shot groups in your testing, the COV would be expected to be approximately 50%. And, the COV will be different for 3-shot groups, 10-shot, 25-shot, 50-shot, etc. 

 

Take a look at the Excel chart below using your data and notice that the COV, on average, is 28.7%. That's very close to the expected COV using 5-shot groups and will converge closer to the 25% value as the size of the sample increases. 

 

There are many other better statistical tools available to determine if your variation is excessive, but COV is the simplest to understand and easiest to use. 

 

Landy

 

 

“In God we trust; all others must bring data.” “Without data, you're just another person with an opinion.” “If you can't describe what you are doing as a process, you don't know what you're doing.” “It is not enough to do your best, you must know what to do, and then do your best.” W. Edwards Deming (October 14, 1900 - December 20, 1993)

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joeb33050 posted this 25 January 2017

 

Hi Joe, 

 

After I read your post and looked at the group ES (Extreme Spread) for the 25 groups you shot, it didn't appear to me that the variation in ES was abnormal. Since I was curious, I decided to conduct a very simple check to possibly verify if your group sizes and group size averages varied more than we would expect to see. 

 

Are you familiar with the term COV (Coefficient Of Variation)? 

 

Again, to keep this very simple, for those who aren't statistical nerds like me, the COV varies based on the number of shots used to form each group.

It's an easy calculation that's nothing more than the Standard Deviation divided by the Average, and if you use Excel, format the cell which contains the formula as a percentage. The end result is a percentage that tells you how much variation, on average, you can expect to see when shooting a string of groups. 

 

In your case, using 5-shot groups, the COV should be approximately 25%.

If you had used 2-shot groups in your testing, the COV would be expected to be approximately 50%. And, the COV will be different for 3-shot groups, 10-shot, 25-shot, 50-shot, etc. 

 

Take a look at the Excel chart below using your data and notice that the COV, on average, is 28.7%. That's very close to the expected COV using 5-shot groups and will converge closer to the 25% value as the size of the sample increases. 

 

There are many other better statistical tools available to determine if your variation is excessive, but COV is the simplest to understand and easiest to use. 

 

Landy

 

Thanks, but you missed the point. The 9 shots all over the paper, twice, is the variation I'm talking about.

joe b. 

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Larry Gibson posted this 25 January 2017

Joe 

Do we know the velocity of the load on 80 - 90 degree days vs the velocity on 50 degree days? 

LMG

Concealment is not cover.........

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HuskerP7M8 posted this 25 January 2017

You're correct. Proves I shouldn't speed read and then post. LOL

Landy

“In God we trust; all others must bring data.” “Without data, you're just another person with an opinion.” “If you can't describe what you are doing as a process, you don't know what you're doing.” “It is not enough to do your best, you must know what to do, and then do your best.” W. Edwards Deming (October 14, 1900 - December 20, 1993)

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joeb33050 posted this 25 January 2017

Joe 

Do we know the velocity of the load on 80 - 90 degree days vs the velocity on 50 degree days? 

LMG

Well, I don't. I don't know how much v varies with t, and can't remember reading anything about it. I gave my chronograph away a while back. A guy came to the range with a radar chronograph a few weeks ago, maybe I need one of those. I've got 21 of the 225646M ctgs left, and a Shilen barrel due today, 9” twist. I'll try the ctgs in the new barrel.

joe b. 

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joeb33050 posted this 26 January 2017

The Shilen 22-250 barrel, 9' twist, went on a Savage M 10, and break in began.After a lot of shooting and cleaning,  The 21 225646M 8/sr4756 loads wouldn't stay in a basketball at 100 yards, so it ain't the temperature or twist or gun or shooter or anything  I can see.

At the end of the session, Hornady 53 gr V Max, 7.5  Titegroup went into 1.2” and .8” for 5 shots at 100 yards.

joe b.  

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Ken Campbell Iowa posted this 27 January 2017

unexpected results ...

some of our greatest breakthroughs in knowledge have come from unexpected results ....  line spectra instead of continous frequency range of energy of atomic emission  ..

...that was the good news ....

hmmmm ...

ken

oh, at times in the past when facing a seemingly paradoxical dilemma ... i reach into my billfold and pull out my little  * rescue * ... card ...

it reads '"  there is something wrong “

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frnkeore posted this 27 January 2017

At this point, with a new barrel, you need to measure the bore and groove size, as well as the bore ride and bands of the bullet. Maybe it fits ok but, you don't know that until it's measured.

If you can't do that, make sure that you push the nose of the bullet into bore, at the muzzle, to see if it engraves well.

Again, I would like to suggest the Lee 55 gr bullet. It has a larger bore riding nose than most of the others. At least try to borrow some.

Frank

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GP Idaho posted this 27 January 2017

Joe:  I have a lot of 22 Lee Bators (55gr.) and 60gr. Saeco bullets cast up if you need some to give a try in the new barrel please feel free to PM me for samples.  Gp

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OU812 posted this 28 January 2017

Barrel fouling, poor bullet to throat fit, inconsistent chamber pressures............and so on.

I am slowly figuring it out...I think?

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