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March 14th, 2011 09:02 PM
#31
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Some clarifications. First and foremost this is not about practice sessions, it is about the number of shots fired at a target.
Second, it has little to do with the gun, the accuarcy of the gun should be a constant.
Third, it is not necessarily about fatigue, but certainly that could be a factor.
Fouth, statistical prediction is based on trials of past performances.
This is pretty similar to a basketball player shooting free throws so here's an example of that. A player has an established record of being an 85% freethrow shooter. That means every freethrow he attempts he has an 85% chance of making it. So let's suppose he's fouled and gets two freethrows. What's the probability that he'll make them both. We can use a Probability Distribution table to solve this. From the table, 2 shots in 2 tries with a probability of 85% gives us 72.3%. What's interesting to me is if he's fouled in the process of shooting a 3 point shot. He has 3 tries to make three shots. Again with the same 85% probability, he has a 61.4% probability of making all three shots. He's getting kinda short changed on the three shot foul.
OK, let's go to shooting. First via past trials we have to establish a probability of getting a hit. Let's say the probability of getting a hit in a prescribed area of the target is 95%. What is the probability of getting 2 hits out of 2 tries. In the probability distrubution table, I look for 2 tries and 2 successes with an independent chance of success of 95%. From the table I get 90.2%
So how about 3 for 3  85.7%
4 for 4  81.5%
5 for 5  77.4%
10 for 10  59.9%
20 for 20  35.8%
And that's as far as my table goes.
So you can see this is base on our past performance and we have to have an meaninfgul probability of success number. I bet none of us have that. But unless you can hit within a prescribed area on a target 100% of the time, you will shoot poorer the more you shoot and it doesn't have to be a lot of shots. Look what the probability is for a 95% shooter is for 20 shots.
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March 14th, 2011 09:08 PM
#32
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I guess I'm in the minority. As I shoot, my groups typically improve. As I finish one string, I pull the target in for a closer inspection. I imagine what I did to explain the results on the paper and adjust the technique as necessary. As the results improve, the frequency of pulling the target in for inspection decreases. Usually my groups and time improve as I remind myself of the basics that in my excitement to shoot I frequently overlook.
I also only put five rounds in the mag at a time for strings, and practice timed combat shooting at 7 yards. Every five rounds, I pause and reflect, but often I will shoot over a hundred rounds before I pack it in.
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March 14th, 2011 10:41 PM
#33
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Indeeed.
Somtimes when i go to the range and i've got plenty of time i'll load only load 25 rounds in my mags. This helps me focus on the group/shot placement. When i go fully loaded i tend to waste more ammo.

March 14th, 2011 11:19 PM
#34
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i play video games so my fingers are in excellent shape and do not get tired after an hour and a half of shooting, your argument is invalid sir.
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March 14th, 2011 11:26 PM
#35
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my 0.02. Fatigue and eventual anticipation of the shot probably play a big role in it.
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March 15th, 2011 06:53 AM
#36
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Originally Posted by GlockJS
my 0.02. Fatigue and eventual anticipation of the shot probably play a big role in it.
This is a point missed by several. If you look at the table in the OP, you'll see that 3 shots produce a bigger group than 2 shots. 4 shots produce a bigger group than 3 shots. This is not the affect of fatigue.
As for anticipation, that's factored in. If a shooter, say in a Bullseye competition has established record of hitting 95% of his shots over the years. All the pressure, all the fatigue, all the whatever is reflected in that average.
I think we've gotten the impression that we need to shoot large numbers of rounds for our groups to spread and then at that magic round count our group size suddenly gets larger. Again looking at the test results in the table, the group size increases dramatically within the first 20 shots. After 20 shots the group size increase is much slower. If fact the group size doubles from two shots to ten shots. It doesn't double again from 10 to 100 shots.
So the most change occurs within the first 20 shots.
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March 15th, 2011 03:37 PM
#37
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Originally Posted by SIXTO
I've said a million times here that 30 minutes and 20 shots is much better time spent than an hour and 200 shots. I know that is not exactly what we are talking about here, but the more time you sit behind the barrel in one setting, the more fatigue sets in and the more prone you are to rushing the shot.
Thats why i shoot no more than 50100 shots at one range setting...100 is a LOT for me at one time, but usually 5075 max.
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March 15th, 2011 04:38 PM
#38
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I had my 20" ss match bbl AR at the range Sunday,hadn't shot it in awhile,I was shooting reloads 21.5 grns H322 55 grn bullet,first five shots were a little high and left I had 4 shots in a jagged line that looked like 3 and 1 about 1/2" right,as my barrel started heating up my pattern opened up a little,my buddy had a box of old winchester 55 grn so I loaded up 20 rounds and fired at different numbers on the target,the winchester really opened my groups up,buddy yells hey I got somea this crap and tossed me a box of wolf black box 55grn,I thought I bet my groups really open up,fired 5 rounds and pulled the target in,all 5 shots were touching
1/2" group,best group of the whole day,I probably shot about 100 rounds of fun.Then switched to pistol
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March 15th, 2011 05:32 PM
#39
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I think it's because the barrel gets hot and is less accurate. I know this is the case with a rifle, not so sure about pistols  but makes sense.

March 15th, 2011 09:44 PM
#40

March 15th, 2011 09:45 PM
#41
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March 15th, 2011 10:07 PM
#42
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So, let me pose a hypothetical..
Let's assume a rifle not a handgun.
Let's assume a completely mechanical set up, trigger pull is mechanical, too.
Let's assume a MOA accuracy.
Once sighted, would the shooting deteriorate over shots fired? Statistically speaking?
Just a question...
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March 16th, 2011 06:52 AM
#43
Senior Moderator
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Originally Posted by oakchas
So, let me pose a hypothetical..
Let's assume a rifle not a handgun.
Let's assume a completely mechanical set up, trigger pull is mechanical, too.
Let's assume a MOA accuracy.
Once sighted, would the shooting deteriorate over shots fired? Statistically speaking?
Just a question...
I believe you can answer that. Here's the setup: exactly the way you said. The test is setup with the target 500 yds away in a shelter that protects the entire test from drafts.
One shot is fired from the setup and the shot placement is recorded. Do you think the next shot fired will be in the very same hole, exactly?
I'm too young to be this old!
Getting old isn't good for you!

March 16th, 2011 10:47 AM
#44
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Originally Posted by Tangle
I ran across this on Wikipedia (therefore you are apprised). It seems that the more shots fired, the larger the group grows. That sounds kind of counterintuitive to me, but here is a table listing the number of shots fired vs group size. All fired from a MOA accuracy gun.
No of shots.....Group Size(′/MOA)
2...................1.77
3...................2.41
5...................3.07
10..................3.81
20..................4.45
100................5.69
I guess the lesson here is if you do get that great, impressive first shot, or 2 shot group, stop shooting, it's just going to get worse.
Without seeing the article or the way the data was collected, I would say that it is merely showing the the small number of shots would be overstating the accuracy due to a sample size that is too small. Plus, I would like to see the conditions in which the gun was shot. Was the barrell cleaned after every shot, every ten shots.... ? How did they compesate for barrell fouling? Also, how much time in between shots? Barrell heat will affect accuracy. The barrell is going to be cooler on the first shot. It would be very hard and time consuming to cool it down to the same temperature as the first shot for every subsequent shot. The type of statistical analysis will have an effect also. Were outliers thrown out? As the sample size increased, the chance for an outlier also increases.

March 16th, 2011 10:58 AM
#45
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This thread has helped my ego. I now know it's not me, it's the statistics! Gotta love that.
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