Thread: Good old Plop shot

that's a new one, whats mpi? The one I deal with loves auditing us

mean point of impact?

whatever the f that 'mean's. Is it like a gun that shoots good groups but each time somewhere else on the target?

How do you even get a random mean?

Originally Posted by Gibo

whatever the f that 'mean's. Is it like a gun that shoots good groups but each time somewhere else on the target?

How do you even get a random mean?

Draw a box around all the shots and the center of that box will be close enough

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Originally Posted by R93

Draw a box around all the shots and the center of that box will be close enough

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I know what mean is. Nothing random about it though.

tis when ya plurry scope base screws are loose.......very plurry random

Originally Posted by Gibo

I know what mean is. Nothing random about it though.

Keep away from the mean ones Gibo. Find a nice one.

Good that you have 'mates' that can take a good opportunity to take the piss out of you thought Philipo.

The theory is that the population of all possible shots has a mean value and each shot has a random deviation from that location.

You try to estimate the location of that mean point of impact from a sample of shots fired on paper. At the same time you are estimating the size of the typical deviation (often we talk about group diameter but its mathematically easier to handle the standard deviation which is the root mean square deviation).

Now, the more shots you fire, the closer the observed sample's mean point of impact is to the theoretical population mean point of impact. You also get more information on the group size.
Groups of 1 shot each are pretty random. Groups of 3 shots are better and usually good enough to sight in with. Sometimes you'll get 3 consecutive shots all on the same side but mostly the mpi will be inside the triangle. Groups of 5 shots will almost always contain the true population MPI within them and you are starting to get an idea how good your grouping is.
So, if someone tries to sight in with 1 or 2 shot groups, they don't know the mpi and they don't know the amount of deviation, so the underlying population mpi will have a lot of randomness compared to where they see the shot fall.

If you're like Phillipo and you already know the grouping is 0.75 MOA then you can adjust pretty quickly to get the gun sighted in within 0.75 MOA by firing one shot at a time.