Are three shot groups valuable?

[LRNut]

Took an old Rem 700 and had one of my rifle builders add a McM stock and a lightweight Brux bbl chambered in 300 RUM. Shot a few ho- hum groups with 200 ABs and then loaded three sets of 3 each 225 ELDs w/88 gr Retumbo at three different seating depths (I am not a ladder fan as seating depth has always been key for me). The second load was good.

So I loaded two more to make it five shots and fired the next day. Any guesses what the group below looked like after two more shots?

 

[birddog 68]

Slightly bigger? lol I always do 3 shots until a group like yours and then jump to a couple 5 shot groups to confirm. I guess I'll have to wait to find out?

 

[LRNut]

So the next day I fired two more and got the group below. For the next week I banged steel with it at my CO place. But as I was doing so, I noticed my velocities were going up (bbl had less than 30 shots when I fired the group below). So this morning I took the same target to my 100 yard range, and fired two more. Seven shots in .483".

I do get a laugh when guys say "I never shoot 3 times at an animal, so why test loads using 5 shot groups?" Well, as you can see, while my seven shot group is great, it got bigger the more shots I fired.

 

[Pdvdh]

That's why I like one shot groups. Go home feeling good about my rifle precision and shooting abilities.

 

[birddog 68]

I always do 5 shot groups to verify and confirm that the load is consistent. Sometimes I shoot 15 shots into the same target at 3 different outings. This is very informative to me!

 

[LRNut]

That's why I like one shot groups. Go home feeling good about my rifle precision and shooting abilities.

The other day I hit my 3" square dead center at 1057; held 1 MOA for spin and a very slight puff of wind (338 Lapua). Quit for the day. In all honesty, I had exactly the same condition the day before and hit exactly where I was aiming (I was 1 MOA left). I was tempted to hold 1/2 MOA just for spin, but I was able to discard the "last bad wind call overcompensation syndrome."

Having the luxury of shooting steel every day every few hours as the wind changes has taught me one thing: a rifle that shoots 7 shots in .483" is great but I would rather have a .75" rifle and be able to call the wind perfectly every time. Sadly, no one can. CO mountains are sooo much harder to call the wind than the AZ desert or a flat plain somewhere.

That said, another lesson I have learned is that it is pretty much a waste of time trying to hit at long range with a relatively inaccurate rifle (1" or worse). A 1 MOA rifle should shoot 7.6 inch groups at 760 yards, which is what I practice at the most when the wind is blowing. My gong is a 15" circle and a "hit" is within a 10"x10" square. If I hit outside of that I never know if the rifle was at fault or if I had a bad wind call. With a 1 MOA rifle I must estimate the wind within .69 mph for a 100% chance of a hit. With a 1/2" rifle my tolerance is 1.4 mph. Big difference. A hit 6" from center with a 1 MOA rifle might have been a bad wind call, but it would have been a hit with a 1/2 MOA rifle. (Actually, it is a bit more complicated than that from a statistical perspective.)

I would also add when I can see mirage my hit rate goes way up; it is also higher using rifles with NF scopes because the mirage is so much easier to see when spinning the parallax knob. My March sucks for that.

 

[HARPERC]

That's why I like one shot groups. Go home feeling good about my rifle precision and shooting abilities.

One shot groups are very useful, as long as it's repeated enough, and always located where you want it.

Similar with 3 shot groups just has to be repeatable.

If you play games that require grouping more rounds, then not very useful.

 

[Bob Wright]

You barrel is speeding up a bit, but still shooting great. I would just put that load on "monitor status" and keep doing the same load. Your brass may fully fire form in a few more firings and raise pressure a bit. So watch for brass measurements as well and adjust powder to stay in this node.

 

[Mikecr]

I believe 3 shots is good for testing.
And when accuracy testing (cold bore) 1 shot at a time is exactly what I need.

 

[Coyote Shadow Tracker]

So the next day I fired two more and got the group below. For the next week I banged steel with it at my CO place. But as I was doing so, I noticed my velocities were going up (bbl had less than 30 shots when I fired the group below). So this morning I took the same target to my 100 yard range, and fired two more. Seven shots in .483".

I do get a laugh when guys say "I never shoot 3 times at an animal, so why test loads using 5 shot groups?" Well, as you can see, while my seven shot group is great, it got bigger the more shots I f

 

[wasskeet]

When they put three in a hole like that with the cold, fouled bore shot being one of them - you've found a great load. I've only had 2 rifles that I felt confident to be able to do that whenever.

 

[comfisherman]

I only care about the 3 shot cold bore groups on my hunting rifles. Varmint and target is a whole different animal.

 

[LRNut]

I only care about the 3 shot cold bore groups on my hunting rifles. Varmint and target is a whole different animal.

Really? Why? My first group was under 1/4 inch. Does that mean my rifle always puts the first three in 1/4"? If it did my group would not have grown larger. Cold bore? In my experience really accurate rifles don't care about cold bore or hot bore (within reason).

The more shots in a group, the better estimate you have for that rifle's inherent accuracy.

 

[Another Casual]

3 shot groups can be useful for some things. The groups can't get smaller by adding shots. In a light rifle that heats up quickly it can save a significant amount of time at the range on a hot day. In a round where you need to cover a lot of ground between min and max charges it saves time and components. I accept that, like you, I'll need to make a second trip to investigate the areas of interest identified with the 3 shot group trip.

I have a heavy barreled 223 and I did 10 shot groups for load development. Reading the groups was a lot easier and you could see as the barrel came on and off a node. If I picked 3 random shots from each of those groups it would be easy to see how 3 shots together aren't helpful.

Let's say you shoot a 3 shot group and two are touching and one is way out there. Maybe it's a good load and you fudged the powder charge or bumped the seating die. Maybe the bullet is a factory reject. Maybe it's a terrible load and the two together were a fluke. One flier in a 10 shot group is easy to disregard, in a 3 shot group it's 33% of your data.

In short, a single hole 3 shot group MAY be a good load, a single hole 10 shot group IS a good load.