[rsilvers]

http://www.shootersjournal.com/Features/WHICHONE.pdf

It shows that using radial standard deviation you can determine which load is best with 40% greater accuracy than using extreme spread EVEN if 25 shots are fired!

It also shows that with 3 shot groups, you can never be more than 47% certain of which load is best. With 10 shot groups, you can be 75% certain, and with 30 shot groups, you can be 90% certain.

[Halo]

Good link. I felt like I was back in my Intro to Statistics class in college!

[rsilvers]

Most people do extreme-spread testing with 5 shot groups. It should bother us to know they are only 57% certain of their results!

What is interesting is that the best method is not significantly more accurate with 5 shot groups than using extreme-spread. RSD seems to make sense with 10 or more shot groups.

30 shot groups using RSD seem to be the way to go as the curve has flattened out.

Another link:
http://fuzzylimey.net/coachtalk/skillanal.html

[rcmodel]

In many varmint and mag rifle calibers, you could burn the barrel out shooting 30 shot groups doing extensive load testing!

By the time you had a load, it would be time to rebarrel it and start over again!

rcmodel

[Walkalong]

With experience, you can tell when a load is "shootin" or not. You will be able to tell if it is ammo, wind, shooter, etc. Many a Benchrester, myself included, has been walking back from the line mumbling something like "The gun is trying to shoot, I just keep getting in the way." or "The rifles shooting, It's just me" They can tell the rifle/load is OK, and that they are messing up.

[USSR]

With experience, you can tell when a load is "shootin" or not. You will be able to tell if it is ammo, wind, shooter, etc.

Walkalong,

When I was shooting in 1,000 yard F Class competition, I would be going along fine and all of a sudden, an "8" would come out of nowhere. My instinct would tell me it must be something I did, and I would not correct and would promptly place my next shot out in the 8 ring as well. Took me a year to break myself of that line of thinking and immediately make a correction.:(

Don

[Walkalong]

See, you could tell. You just needed to adjust. :D

I have seen guys change loads, scopes, even barrels, and continue to shoot poorly. It wasn't the rifle, it was them. 95% of the time it is us, the shooter just having a bad day. It can be tricky knowing when it is really the equipment, but with experience, we figure it out sooner than later, don't we.

Of course I am talking about 100 and 200 yards and trying to put em all in one hole, and you are shooting long range for score, but they are both demanding and difficult. :)

When I had one go out of the group, I assumed it was me, and made a correction. If unexplained things continued, then I would suspect equipment.

[rsilvers]

http://www.rawilson.net/shareware/index.html

RSI Shooting Lab also does it.

[rsilvers]

http://www.rawilson.net/shareware/Gsc/madd.pdf