Question for precision and reloading geeks

[NevadaMike]

Bipod is bouncing
you need carpet or something on the bench

Great idea thanks!

 

[Shortschaf]

Twist is 1:8

Ok then stability shouldn't be a problem. (Will cause bad accuracy at distance with simultaneous good accuracy at 100)

So I agree with others on checking for loose components/screws or stock contacting barrel to start

 

[Lawnboi]

I would go retry on a better day. Maybe check torque on my rifle as well.

Personally I don’t subscribe to the hard bipod load because it can’t easily be replicated in the field. A 6 creed even if lightbwith a suppressor, recoil shouldn’t be an issue.

Strange things can happen when weather shifts. That’s a little large. After that much shooting in a day fatigue may not be helping. On top of that be aware that mirage can cause some shifts when things get hot.

I highly doubt your 1moa load went to 5moa at 300

 

[Vern400]

So if the bullet is heading to the right at 100 yards and goes to sleep, it veers to the left past 100 yards? And bullets going left veer right? Low bullets veer up? High bullets veer down? How do they know when and where to veer?

No, it's a wobble. So the path is somewhat like a tight corkscrew. Ever seen someone throw a football that wobbles for a short distance and then smooths out and flies straight? It's like that only a bit faster. This is why almost all short-range benchrest shooters use flat base bullets. They stabilize quicker.

I shot several 0.68 inch groups of 5 (100 yd).
Then I shot several 1 inch groups at 200. No way! (I thought). I alternated groups at 100/200/100. The 200 yd groups were never once 2x as big as the 100 yd groups. I called Nosler tech support with pictures, and they were like, "yeah, you found it. That is indeed a thing".

 

[Harvey_NW]

Also might not hurt to get a cheap front bag like the Caldwell Tack Driver for confirming loads off the bench. I'm way more solid on bags than a bipod so I try to do all my verification on them first, then switch to the bipod and go prone.

 

[Axlrod]

No, it's a wobble. So the path is somewhat like a tight corkscrew. Ever seen someone throw a football that wobbles for a short distance and then smooths out and flies straight? It's like that only a bit faster. This is why almost all short-range benchrest shooters use flat base bullets. They stabilize quicker.

I shot several 0.68 inch groups of 5 (100 yd).
Then I shot several 1 inch groups at 200. No way! (I thought). I alternated groups at 100/200/100. The 200 yd groups were never once 2x as big as the 100 yd groups. I called Nosler tech support with pictures, and they were like, "yeah, you found it. That is indeed a thing".

The Nosler "tech" is using imaginary science.
Brian Litz, the ballistician from Berger, has had an open challenge since 2015, to anyone that could prove non-linear dispersion (bullets going to sleep). In 9 years it has never happened.

You are being redirected...

You are comparing 2 seperate groups. If you want real data, set up a target at 100 yards and a target behind it at 300 yards. Shoot thru the first one and into the second one.
What you will find is 1) the group shape is always the same 2) the group at 300 yards is always 3 times larger than the one at 100 yards.

 

[Vern400]

The Nosler "tech" is using imaginary science.
Brian Litz, the ballistician from Berger, has had an open challenge since 2015, to anyone that could prove non-linear dispersion (bullets going to sleep). In 9 years it has never happened.

You are being redirected...

You are comparing 2 seperate groups. If you want real data, set up a target at 100 yards and a target behind it at 300 yards. Shoot thru the first one and into the second one.
What you will find is 1) the group shape is always the same 2) the group at 300 yards is always 3 times larger than the one at 100 yards.

You said
1. Someone disagrees. I'm sure you're right there
2 I was comparing two groups. I wasn't.
3 a virtually impossible test would prove something. A first Target any of us has available would certainly upset the bullet path for a second target.
4 dispersion is always linear with distance.
It is not.

I'm always open to learning from other people. I can only relay my experiences and be truthful about it. It was never my intention to cause consternation. There are many people who understand more about exterior ballistics than me.
But this is not a solid argument you make.

Thanks for commenting.

 

[wintersoldia]

no one became an expert overnight buddy my advice is take your time and try all the valuables
You get perfect when you have had enough practice

 

[ResearchinStuff]

I wonder if your Mk4hd crapped out. Have a reliable scope you can put on there?

 

[Castle Rock]

It is easy to measure the same group at various distances using shotmarker

 

[NevadaMike]

I wonder if your Mk4hd crapped out. Have a reliable scope you can put on there?

Always a possibility but my Leupold scopes have always been good. I am going to load up a new batch and I will test at 100 again but I had two touching just before dialing out to 300. It was not submitted to a drop test yet.

 

[wind gypsy]

It is easy to measure the same group at various distances using shotmarker

That was my thought as well. It would be easy to test it now with current technology, no need for it to hit anything at the first "target".

Stolen from the hide:

 

[Lawnboi]

I think what a lot of people see with dispersion at 100 is caused mainly by mirage and parallax, sometimes together. Not uncommon to have to change my parralax once my barrel is hot when shooting for zero. Getting perfect parralax with a high power scope at 100 can be difficult, at 4 or 500 yards it’s not hard at all.

 

[Shortschaf]

4 dispersion is always linear with distance.
It is not.

I think the point @Axlrod was trying to make is that actual experts on the subject completely disagree with your above statement.

Not that you can't observe smaller, seperate group sizes at distance, but that the theory of self correcting flight is not sound.

 

[Vern400]

Sometimes the experts don't agree with the experts. Nosler thinks that flat base bullets stabilize and are frequently more accurate at close ranges for that reason. Obviously long slender boat tail bullets or Superior as you reach 300 and 400 yd. But don't go to 100 or 200 yd interest contest expecting to win with a high BC bullet because it pretty much ain't going to happen.

Attached is one of several emails from Nosler tech support.

That's all I got.

 

[ResearchinStuff]

any aeronautical/astronautical engineers on here that can talk intelligently about 4 and 6 DOF aerodynamics and explain in detail how/why "going to sleep" doesn't actually happen?

no disrespect to hornady Nosler, but they do not have the $ to afford the folks who actually understand aerodynamics and ballistics at this level.

 

[Harvey_NW]

any aeronautical/astronautical engineers on here that can talk intelligently about 4 and 6 DOF aerodynamics and explain in detail how/why "going to sleep" doesn't actually happen?

no disrespect to hornady, but they do not have the $ to afford the folks who actually understand aerodynamics and ballistics at this level.

Have you listened to the external ballistics episodes? I think Jayden understands what's going on, and can substantiate it. There are also publications by Litz, and the government on the matter. I'm not an engineer, but I've read and listened to a lot of context on the subject trying to comprehend it, so I'll take a stab. The way I understand it, there is an initial yaw cycle and the bullets do "go to sleep" (gyroscopically stabilize), and then velocity, center of gravity, center of pressure, drag, wind deflection, etc., determines what happens downrange. The conflict is that yaw cycle doesn't effect the flight path the way people who believe in non-linear dispersion think it does, and has never been proven in formal testing. Same as "nodes" identified in Audette ladder tests. Longer range shots in a real world environment induces the potential for physical characteristics or effects like wind deflection, drag, magnus, Coriolis, to possibly show up and further increase dispersion.

 

[ResearchinStuff]

i have listened to them, and recall Jamie saying explicitly that they do not go to sleep in a manner that results in smaller groups at longer ranges. It's been a few months, and I was driving in heavy traffic, so maybe i misheard.

also, realized an error in my previous post, meant to call out Nosler, who supplied the info in post 35.

 

[Harvey_NW]

i have listend to them, and recall Jamie saying explicitly that they do not go to sleep in a manner that results in smaller groups at longer ranges. It's been a few months, and I was driving in heavy traffic, so maybe i misheard.

No, I'm pretty sure he says that. Just that there technically IS a yaw cycle before gyroscopically stabilizing.

also, realized an error in my previous post, meant to call out Nosler, who supplied the info in post 35.

I was going to say, he dives pretty deep into 4 DOF and 6 DOF in a couple episodes. I actually listened to the 4 DOF one yesterday and will have to probably listen to it a few more times to get it to sink in (I listen while driving so sometimes what I retain is patchy too) because that's some dense material.

 

[ResearchinStuff]

my takeaway was that Jamie knows 4 and 6 dof exist, and with difficulty (i.e. the years of development effort they mentioned) was able to get the math to work well enough to program their 4dof app. However, there are people out there at companies like SpaceX, lockheed and northrop that are solving 6 dof flight problems all day every day. hopefully one of them finds this thread