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Offhand Breech vs Fixed (Read 17559 times)

westerner Frequent Elocutionist Offline deleted posts and threads record holder. Posts: 11474 Location: Why, out West of course Joined: May 29^th, 2006	Re: Offhand Breech vs Fixed Reply #30 - Mar 10^th, 2014 at 11:06pm	Print Post
	When I'm shooting my best OH, groups can measure and usually measure about ten to twelve inches. I don't consider them groups. More like patterns. Most of the time I have one or two wide shots. All this about equations and radius and so on makes no sense to me. Looks like three threads on this same subject. Joe.

	A blind squirrel runs into a tree every once in a while.
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joeb33050 Frequent Elocutionist Offline Posts: 2613 Location: Marathon, FL Joined: Apr 20^th, 2004	Re: Offhand Breech vs Fixed Reply #31 - Mar 11^th, 2014 at 5:18am	Print Post
	rgchristensen wrote on Mar 10^th, 2014 at 8:07pm: FRANK: Group size isn't the best way to measure variance, better is something that considers all the shots and not just the widest two. Mean radius is better, and root-mean-square is better yet, in that it is more amenable to valid statistical comparisons. CHRIS RGChristensen I disagree.(I don't think he means variance, I think he means accuracy. RMS^2 = variance.) Group size does not just consider the widest two shots, but is the range, and the range is frequently used to estimate standard deviation; as in Cat whisperer's imaginary x bar and r charts. Mean radius and group size are mathematically related such that if we know one we know-or can calculate-the other. The root mean square deviation of a set of numbers is the standard deviation of that set, and is also mathematically related to group size such that if one is known the other can be calculated. Mean radius and s.d. are essentially the same as group size, are difficult to understand, aren't commonly used, and to my mind are a bit pretentious.
	« Last Edit: Mar 11^th, 2014 at 6:00am by joeb33050 »
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joeb33050 Frequent Elocutionist Offline Posts: 2613 Location: Marathon, FL Joined: Apr 20^th, 2004	Re: Offhand Breech vs Fixed Reply #32 - Mar 11^th, 2014 at 5:35am	Print Post
	frnkeore wrote on Mar 8^th, 2014 at 5:51pm: Ok, your going to have to school me on this......... I don't understand how a group that averages 3" as compared to another bunch of groups that average 4" (approx. 1/2 min difference) and be made to expect to be a .041 difference? Unless statistics favor the OH shooter by a lot more than a bench shooter. Frank Here's how it works. If the shooter can hold within a 3 moa circle and the gun will shoot in a 1 moa circle, the average total group size is the square root of 3 sqrd+1 sgrd = sqrt of 9+1= sqrt 10 = 3.16 moa. If we improve the gun so it shoots .5 moa, the numbers become sqrt of 3 sqrd+.5 sqrd = sqrt 9+.25 = sqrt 9.25 = 3.04 moa. We reduced gun group size by .5moa, but total group size went down only .12 moa. Shooter affects accuracy much more than gun.

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joeb33050 Frequent Elocutionist Offline Posts: 2613 Location: Marathon, FL Joined: Apr 20^th, 2004	Re: Offhand Breech vs Fixed Reply #33 - Mar 11^th, 2014 at 5:58am	Print Post
	Assume that variables, acting alone, cause groups of certain sizes. Powder charge variation *alone* might work so: +/- 0 grain = .1 moa group; +/- .1 gr = .25 moa; +/- .2 gr = .6 moa. Then there are group sizes for bullet weight variation and seating depth and powder lot and .... How do these variables/group sizes add? Let there be only 2 variables, shooter with 3moa group size and gun with 1 moa group size. Make a 3" paper disc and a 1" paper disc. Lay the 3" disc on the table, repeatedly drop the 1" disc on top of the 3" disc such that they touch. Sometimes we get a "snow man", a total group size of 3" +1" = 4", the maximum. Sometimes the 1" disc is all inside the 3" disc. total group size = 3", the minimum. Total group size varies between 3" and 4". The average total group size is sqrt (3 sqrd +1 sqrd) = sqrt 10 = 3.16".
	« Last Edit: Mar 11^th, 2014 at 6:24am by joeb33050 »

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Cat_Whisperer Frequent Elocutionist Offline No 1, 9.3x74R Posts: 3878 Location: Mountains of Virginia Joined: Apr 17^th, 2004	Re: Offhand Breech vs Fixed Reply #34 - Mar 11^th, 2014 at 6:07am	Print Post
	joeb33050 wrote on Mar 11^th, 2014 at 5:58am: Let variables cause groups of certain sizes. ... Your first sentence does not make sense, could you reword it. The rest is GOOD.

	Cat Whisperer (trk) Chief of Smoke Pulaski Coehorn Works and Skunk Works Drafted May 1970, Retired Maj. U.S.Army assra #9885
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westerner Frequent Elocutionist Offline deleted posts and threads record holder. Posts: 11474 Location: Why, out West of course Joined: May 29^th, 2006	Re: Offhand Breech vs Fixed Reply #35 - Mar 11^th, 2014 at 6:20am	Print Post
	Psychobabble............ Joe.

	A blind squirrel runs into a tree every once in a while.
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joeb33050 Frequent Elocutionist Offline Posts: 2613 Location: Marathon, FL Joined: Apr 20^th, 2004	Re: Offhand Breech vs Fixed Reply #36 - Mar 11^th, 2014 at 6:28am	Print Post
	westerner wrote on Mar 11^th, 2014 at 6:20am: Psychobabble............ Joe. This is one of the most important notions in understanding how accuracy occurs, changes and is improved by controlling variables. Get those noodles out of your eyes!


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westerner Frequent Elocutionist Offline deleted posts and threads record holder. Posts: 11474 Location: Why, out West of course Joined: May 29^th, 2006	Re: Offhand Breech vs Fixed Reply #37 - Mar 11^th, 2014 at 6:49am	Print Post
	joeb33050 wrote on Mar 11^th, 2014 at 6:28am: westerner wrote on Mar 11^th, 2014 at 6:20am: Psychobabble............ Joe. This is one of the most important notions in understanding how accuracy occurs, changes and is improved by controlling variables. Get those noodles out of your eyes! Thus......... more pschycobabble.........

	A blind squirrel runs into a tree every once in a while.
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rgchristensen Frequent Elocutionist Offline Posts: 1093 Joined: Jan 2^nd, 2014	Re: Offhand Breech vs Fixed Reply #38 - Mar 11^th, 2014 at 10:00am	Print Post
	All this at 6AM this morning!! I guess you have to get up early in the AM to get ahead of these guys!! Let me give this up by remarking that "by their nature, uncertainties are not well known or easy to measure." CHRIS RGChristensen


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rgchristensen Frequent Elocutionist Offline Posts: 1093 Joined: Jan 2^nd, 2014	Re: Offhand Breech vs Fixed Reply #39 - Mar 11^th, 2014 at 10:11am	Print Post
	joeb: Mean radius, radial SD, and group size can be inferred from one another ONLY if you know the distribution. Given that one can prove a Gaussian distribution (not easy, nor safe to assume), you can readily relate these quantities. For other distributions, the math can get hairy. Interesting parallels are found in the evaluation of shotgun patterns. CHRIS RGChristensen


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Lefty38-55 Senior Forum Member Offline Posts: 366 Location: New England Joined: Sep 11^th, 2013	Re: Offhand Breech vs Fixed Reply #40 - Mar 11^th, 2014 at 10:18am	Print Post
	rgchristensen wrote on Mar 11^th, 2014 at 10:11am: Given that one can prove a Gaussian distribution (not easy, nor safe to assume), you can readily relate these quantities. For other distributions, the math can get hairy. Look at Joe's target above ... the low and high shots - called or not - are due to an assignable cause. That blows the Gaussian distribution quotient out of the water, as it only works on normal distributions. I personally don't believe statistical predictions can be made with the groups most people shoot. We have found the problem folks - and it be within us! Like others have said, a good offhand group and/or score is more predicate on the performance of the shooter than the basic inherent capabilities of the said equipment. Eliminate the errant shots by continuously working on your technique ... and your scores and groups will improve!

	All of my single shots shoot one tiny ragged hole with cast bullets ... it's just the following shots that tend to open up my groups ...
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joeb33050 Frequent Elocutionist Offline Posts: 2613 Location: Marathon, FL Joined: Apr 20^th, 2004	Re: Offhand Breech vs Fixed Reply #41 - Mar 11^th, 2014 at 12:29pm	Print Post
	Well Chris, I assume a normal distribution, as do many others. I think it's both a safe and reasonable assumption, and Karl agreed, last time we spoke. As for "mean radius", the assumption is the definition of the center location. And we know that there are quite a few different centers of n points. Aren't there? rgchristensen wrote on Mar 11^th, 2014 at 10:11am: joeb: Mean radius, radial SD, and group size can be inferred from one another ONLY if you know the distribution. Given that one can prove a Gaussian distribution (not easy, nor safe to assume), you can readily relate these quantities. For other distributions, the math can get hairy. Interesting parallels are found in the evaluation of shotgun patterns. CHRIS RGChristensen


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Cat_Whisperer Frequent Elocutionist Offline No 1, 9.3x74R Posts: 3878 Location: Mountains of Virginia Joined: Apr 17^th, 2004	Re: Offhand Breech vs Fixed Reply #42 - Mar 11^th, 2014 at 1:00pm	Print Post
	Lefty38-55 wrote on Mar 11^th, 2014 at 10:18am: ... I personally don't believe statistical predictions can be made with the groups most people shoot. We have found the problem folks - and it be within us! ... Agreed. BUT there are still some good uses for statistics. Descriptive statistics are a good way to get a handle on what is. Finding the 'whys' is, in the statistical approach, MUCH more complicated and not often done; or done with some presumptious assumptions.

	Cat Whisperer (trk) Chief of Smoke Pulaski Coehorn Works and Skunk Works Drafted May 1970, Retired Maj. U.S.Army assra #9885
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40_Rod Frequent Elocutionist Offline Extremism in the persuit of accuracy is not a vice Posts: 4285 Location: Knoxville, TN Joined: Apr 20^th, 2004	Re: Offhand Breech vs Fixed Reply #43 - Mar 12^th, 2014 at 8:54am	Print Post
	The short answer is that if you can stay consistently inside the 20 ring you are shooting in the top 10% of shooters at any given match. 40 Rod


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Lefty38-55 Senior Forum Member Offline Posts: 366 Location: New England Joined: Sep 11^th, 2013	Re: Offhand Breech vs Fixed Reply #44 - Mar 12^th, 2014 at 3:31pm	Print Post
	40_Rod wrote on Mar 12^th, 2014 at 8:54am: The short answer is that if you can stay consistently inside the 20 ring you are shooting in the top 10% of shooters at any given match. Thank you! Now THAT gives me a *benchmark to shoot* for !**

	All of my single shots shoot one tiny ragged hole with cast bullets ... it's just the following shots that tend to open up my groups ...
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