An Argument for 3 Shot Groups for Testing Precision

try some 3 and 5 groups in the same test and see if the 5 shot groups provide any more info

Hmmm so many things to consider...and your current methodology isn’t bad at all...but my god it’s time consuming. 


I test pellets when it’s windy. And I test them when it’s calm. I can tell in ten minutes in either condition whether I have a good pellet for the rifle I’m shooting. At 50 yards you should get three shots falling into one hole occasionally. You’ll rarely get five falling into one hole. If that’s not happening with a pellet I’m testing. I MoveOn. Once I find one that shoots really good. Then I start looking at velocities for that pellet. Almost all pellets (except EBR rifles) shoot best right around 885 ft./s. A gentleman named YRRAH taught me this. He lived down under in Australia, he called it OZ. I tested for about a year, to prove him wrong. He was NOT wrong. It not only need to shoot well in Calm conditions, it needs to shoot well and at least consistently in the wind.

Then I try to find a lot and diameter of the pellets that I’ve just identified as shooting the best in this certain rifle out a certain velocity, I buy as many of those as I can get my hands on. Usually they shoot really well in all of my rifles. Good lots of pellets are very precious. I’ve been shooting what I call silver tin 18 Grain JSbs this morning. They are awesome. They haven’t made them for 10 years.

keep doing what you’re doing. Just maybe think about some other modifications.

three shot groups that are really tiny are really fun. And they mean nothing statistically. IMO. 


mike

You probably aren’t missing anything so long as you are analyzing a large sample of 3 shot groups. Most people are using one selected group to make definitive claims about their equipment.


Mike

I’ll look for the post on here that contained a link to using various sized groups to determine accuracy and precision. In the study it concluded that statistically 3 shot groups did not provide enough information to be definitive. The study was with firearms, not airguns. The second link has the associated math…


https://www.thetruthaboutguns.com/understanding-rifle-precision/amp/

http://www.geoffrey-kolbe.com/articles/rimfire_accuracy/group_statistics.htm

From a purely scientific method standpoint...data data data...the more data you have the more accuracy you have.

3 shot group doesn't say much. So if I shoot 2 shot and its hole in hole at 100 yard. Can i say my gun shots single hole at 100 yard? How about 1 shot group. Oh I hit bullseye at 300 yards with 1 group. My gun is so accurate. No, its just luck. Ted once said that 10 shot is the min. Anyone can do .01 at 100 yards with 3 shots but can someone do .01 at 100 yards with 10 shots. Nope.

A very large sampling of 3 shot groups that is averaged would be valid.


Mike 

A bunch of people say a shot group is only 3 shots butttt I feel like consistency and accuracy go hand in hand. Sure you might have some awesome 3 shot groups but can you do it over and over? I always do 10 shot groups. Whats the harm in trying to repeat accuracy with more shots? I don't get people that rant over groups being only 3 shots.

It’s interesting stuff. I have the ability to shoot in LDs tunnel at 52 yards. No wind. So when I get to the point that I am undecided between two pellets, I shoot in the tunnel like the below, four 5 shot groups with each pellet. One after the other without cherry picking. What I posted is when I was trying to decide which .30 pellet to use at EBR 2018 with the FX Bobcat Mk2. I finally decided on the 44.75 since the last group I shot was lower left, the groups were slightly smaller, and it just seemed to be more “predictable” in the wind outside the tunnel at 100 yards.

I think the 3 shot group thing came from shooting high power, firearm, hunting rifles. The barrel will heat up and cause fliers and who gets more than 3 shots at game anyway. With airguns, you can shoot as many in a group as you want that matches your discipline.

My two cents: I shot some MOA and below 3-shot groups at 100 yards. But few and between 5-shots, and no 10-shot groups. Shooter's error?

I often use three shot groups to avoid poi drift changes due to wind. I can usually manage a three shot group between wind changes but with a five shot a group that is seldom the case. I can do multiple three shot groups if needed. But I only do five shots when there is next to no wind which is very seldom.

del

I collect best data when there's no wind like between 11pm and 4am. Checking the weather forecast mandatory either way.

I never check for data when it's forecasted to be expecting 5mph+ winds. Useful to Kentucky windage a little bird at 65+ yards though.