Elements of dispersion-- why don't I get 1 hole groups?

[stagpanther]

The latest podcast by Hornady is excellent and does a great job putting some complex variables into easy to understand explanations.

[Scorch]

An old friend once told me "after the first shot, the groups can only get bigger". That said, consistency is the key to success. Absolutely no variation in the cartridges, no movement in the stock, no movement in the barrel, no wiggle in the trigger, no variation in shot-to-shot trigger pull, no variation in cheek weld, no variation in how you pull the trigger. Essentially, everything has to be exactly the same from one shot to the next. So it's easy! Just be a robot!

[higgite]

And the barrel has to be the same temperature for every shot. And the same level of cleanliness. And, and, and...

[Rimfire5]

Scorch,

You are right on.
IMO, the shooter set-up variation and trigger discipline causes most of the variation.
That is why test targets from custom rifle manufactures are usually shot with solid fixtures (not lead sleds).

I have test targets from Cooper and Les Baer that are all 0.1 or less with factory ammo.

[Recycled bullet]

The entire purpose of all my handloading experiments to satisfy a two step process: 1) is to clarify, review and if possible narrow the gap between operator error and equipment malfunction, and 2) it's what I would like to be doing.

Twenty shot groups satisfy both requirements for me.

[lugerstew]

I have watched a few of their podcasts now, they are very informative and make you understand all the variables is ballistics, they sound like they really know what they are talking about.
I would love to ask them though, since they work for Hornady, do they always use Hornady components? IMO Hornady brass is just mediocre quality, I would almost bet that they are using better quality brass like Lapua or Peterson or?

[stagpanther]

I've watched some of them--but I thought this was one of the best that I've seen so far.

[Unclenick]

It's all stuff that's been discussed here and on other forums over the years, but nice to see it in one place.

Originally Posted by Rimfire5

IMO, the shooter set-up variation and trigger discipline causes most of the variation.

That's because most shooters are not top-tier. When you get to top-tier marksmen, it often is no longer true, and all sorts of mechanical limitations of the equipment can be detected by them. In one of the books mentioned in the video, Harold Vaughn's Rifle Accuracy Facts, he induces dispersion with intentionally poor cartridge concentricity in loads fired from a special 6 PPC rifle that is built into a machine rest that has had all the deflecting recoil moments determined and eliminated, and firing that in his 100-yard sewer pipe range, shoots the same load into one hole consistently when the cartridges are concentric. A.A. Abatiello did something analogous with human shooters '60s by getting top-tier marksmen with match Springfields to shoot samples from 47 lot numbers of National Match ammunition that were first sorted by concentricity and was able to make a calculation of the effect based on the physics of the bullet's orbital off-center CG that matched with the added dispersion in the groups the shooters were turning in with that ammo.

Originally Posted by lugerstew

…do they always use Hornady components?

If you use their online 4 DOF calculator, you will find some Berger, Lapua, Sierra, and Warner Tool, and a couple of Nosler bullets have been included in their list of those they have measured drag functions for with their Doppler radar setup. I think you can expect them to want to know how their product compares to others, so they will be testing other things for that information and to decide what is worth trying to improve on in their own line. What you can't expect is that they will disclose when someone else's stuff does better. In the case of brass, so to speak, you can bet they have price points they don't want to exceed and, thus, will have limits on what they will spend to make brass as precisely as some others do. However, machining, in general, keeps getting more precise, so there may come a time when you can't really tell much difference between brands, accuracy-wise.

[Bart B.]

Checking 100-yard benchrest records shows the several group aggregates are about 1/3rd inch.

[old roper]

Here smallest 100yd group.

https://bulletin.accurateshooter.com...up-in-history/

[Scorch]

Here smallest 100yd group

And if I shot a group 10 times that size in competition I would likely still win the competition. Jim Carmichael won a match and set a class record 15-20 years ago with a group right around 1/4". An awful lot of club matches are won with pretty modest groups. If you can shoot a 10-shot groups around 1/8" in competition you are in pretty refined company. I remember an old friend of mine (a pretty good shooter) winning a match with around .010" difference in aggregate score.

[44 AMP]

why don't I get 1 hole groups?

Because you shoot more than once!

[higgite]

What’s the big deal about shooting one hole groups? I do that routinely with 9mm pistols freehand. Takes 50 to 100 rounds and the hole is usually about 2 inches in diameter.

[Metal god]

Higgite : me too , at 100yds . Dispersion-smersion bla-bla-bla