Plugged flasholes--does it hurt anything?

[snuffy]

I didn't realize that you were calculating SD on only five shots. You need more than five data points for standard-deviation to be meaningful. I like twenty or more. Just because your chrono spits it out doesn't make it meaningful.

I know that, but since I was shooting 5 shot groups I included it. It does NOT mean nothing though.

I think I will shoot 10 shot groups next time. The chrono will record and evaluate up 99 shots, so I'll just let it run. The paper groups will also be more meaningful.

 

[learn2shoot]

Bench rest shooters use a tool to remove the 'dingus' from the inside of the case. (That's the brass chunk that was punched out when the flash hole was formed.)

now, now we all learned in November 2000 - that this is called a "chad"

 

[WayneConrad]

I know that, but since I was shooting 5 shot groups I included it. It does NOT mean nothing though.

You're in the world of statistical sampling, and you need a large enough sample to have a representative sample of the data set. Five isn't enough. For a standard deviation, five data points is the sound of one hand clapping. Ten is better, twenty is where I start having confidence is the numbers.

 

[rc109a]

Rcmodel: I can start a flash hole plugging service and you can sit in as an adviser or Q/A role. How much could we charge and would it be by the round or pound?...lol

 

[snuffy]

Wayne, I know almost nothing about statistics, so I take what I get from the chrono and file it for reference only. But I still believe that it's worth something. It certainly shows the difference between a load with a SD of say 10 to a load with a SD of say 100. The ES is also an indicator of a consistent load with a powder of the correct burn rate for the bullet, case and other variables.

I know that SD is a prediction of what the same load would do for velocity on a + or - basis. The 5 round group would make that prediction less valid, but it would be of some value.

Now if I could figure out what AD is, I'd be able to either forget it or assign some value to it.

 

[rcmodel]

How much could we charge and would it be by the round or pound?...lol

Hey! Business opportunity!
I can see this will require a lot of thought & planning though.

Of course there will probably be an accuracy difference between:
* Corn cob vis walnut vis Kitty Litter.
* Treated and untreated.
* Wheel polish vis Flitz.
* Red vis Green vis natural color.
* RCBS vis Lyman vis Lizard-Litter grain size.

I'll have to get back to you later after more thought.

I'm busy pounding sand in a rat hole right now.

PS: Snuffy
Hope you take this good natured ribbing in the way it is being offered. All in good fun!
I am anxious to see the results of your further testing.

rcmodel

 

[Smokey Joe]

Bugetary needs...

Rcmodel--You are obviously propounding a LOT of scientific testing here. You'll need me as a consultant to help you write up a request for government and foundation funding to support your research.

Gummint will probably have to let us use the White Sands Proving Ground for the outdoor range work, and at least a couple of Cray supercomputers to analyze the data. Not to mention a staff and some office space.

I imagine that for no more than a trifling $10 to 15 million, we'd be able to come up with some tentative, preliminary results, and a progress report.

Oh, and doctorates all 'round.

BTW, you forgot "nothing" as a hole plug; that's our control--we have to keep this scientific, y'know!

For pounding sand in a rat hole, send that off to MIT--we'll have some graduate engineering student design a computer-controlled, hydraulic ram powered, rat-hole-sand-pounder. And the Michigan Tech geologists will want to chime in with the differences in grades and sources of sand, and their differing behaviors under load.

The research possibilities boggle...

 

[snuffy]

Heh heh, I'm laughing right along with you guys, better to laugh WITH some one than be laughed at! Hopefully I will get up to the range this weekend, I'll post what I find out then.

 

[MutinousDoug]

Snuffy,
As long as you gain from this thread that the smaller your sample size= the lower your SD (and AD and all other statistical data reductions will be, because a sample size of one: SD=0 and AD=0). OTOH the larger your sample size is, the more confidence you have that you have captured the total variance (SD and AD, for instance) then you'll know what the statisticians (the honest ones) are trying to do with numbers.
Keep adding to your sample size, and when the SD and AD quit getting larger, you have arrived at a "statistically significant" sample population. No further statistical information can be gained by adding to the pool, at that point. All depends on where you want to put the decimal point in front of your confidence factor.
5 data points means you have a (roughly) 50% confidence that your numbers won't get bigger. 9 data points means you may have a 90% factor. 19 points means a 95% factor. 99 data points=99% (all depending on the size of your total population vs sample size).

 

[Walkalong]

Dingus; dinguses. Doofus, doofuses

Dingus: Dingus, Dinguses, Dingi.

Moose: Moose, Mooses, Moosi

Mouse: Mouse, Mice, Meeces

So easy a kinnergartner kan do it.

Me. I am going to continue to make sure none of the flash holes have a dingus, or a piece of corncob in them.

 

[The Bushmaster]

I solved this problem years ago by purchasing media that's too fine to get caught in the flash hole...I'd have to glue them together to perform this "experiment". But this has been a entertaining read though...Even has an English lesson in it...

 

[snuffy]

Wow! 28 days later, I finally get to the range. To shoot some more groups with the plugged/unplugged flasholes. With all the rain we've had, the range was flooded till last week.



There's 15 rounds in each group. The chrono was missing a few rounds, the sun was getting low in the west, clear blue skys overhead. So here's the chrono readings;
12 rounds plugged flasholes
av. 2960
hi. 2997
lo. 2924
es. 73.4
sd. 23.5
ad. 17.4

13 rounds unplugged flasholes
av. 2944
hi.2966
lo. 2920
es. 46.0
sd. 14.4
ad. 11.4

I can't really make any firm conclusions. If it weren't for 2 fliers in the unplugged group, it would be easy to see it's the tighter group. Also. the chronograph readings were opposite to what they were last time!

I guess I wasted 50 rounds of otherwise good ammo trying to prove the unprovable. I could keep trying this, maybe 4 more sessions might show a clear winner. Maybe a bigger caliber would show it quicker. To heck with it, I've got better things to do.

Any day spent shooting beats the heck out of any day at work! But you got to work to afford the shooting, such is life!