High Group Variance within a Ladder Test

[birddog 68]

Is there any chance that deeper seating might improve groups versus being as close to the lands as I can get?

If you do a search you will find that some people find the seating depth first before tweaking with the charge.
I used the Berger method for some 154 interbond in my 280 AI which is close as possible and shortening OAL in .030 increments (although I did .020) with a middle of the road charge. I must say it worked well.

 

[FireFlyFishing]

Nodes are a fairy tale. If you shot a 20 shot group or some other large number that is statistically meaningful, it will probably fill in and look like group C, just with more holes.

According to my load development, definitely not a fairy tale.

 

[QuietTexan]

If the "good" groups are over an inch, you have a mechanical issue in the rifle to work on still, or the bullet/powder match is not suitable. Sucks if you have a lot of components, but fighting a mismatch is begging to be frustrated. What does it do with factory ammo?

Personally if I got a discount rifle shooting about an inch with Red box bullets I'd call it good, stop messing around with lead development, and shoot more/further.

it will probably fill in and look like group C, just with more holes.

Yes. Group C isn't a "massive outlier" because if he repeats this same ladder test four more times there's a decent chance the other groups open up to a similar average, and even that C shoots a decent group somewhere in there. So far the rifle has shown to be at best 1.1MOA capable, and that's being generous assuming he can get repeatable results out of one of the other groups.

Will Frye, how many different 20 shot groups should he shoot, and specifically, at what charge weights to determine the best charge weight?

I know you're being sarcastic because Will said nodes are a myth, but the truth is that three shots at a time resulting in these 1MOA+ groups aren't telling him anything other the rifle isn't capable of much better than an inch right now. Tuning happens after major issues are solved. At 1MOA+ there are major issues that hide the result of load tuning. This is a 7mm-08 not a 30-375 Weatheryby, the base precision of the rifle should be better than what those groups show. If he comes back and says the rifle shoots bugholes with facotry ammo then all I'm seeing here is component mismach.

If he comes back as says factory ammo does about the same groups as this, that's what the barrel can produce. It's a Savage Axis II, not a benchrest rifle. I wouldn't waste time chasing the load any further and would start using the heck out of it how it is.

Caveat - he should find the max load for the combination. If he's still 2 grains under need to go up and hit the top and see what happens there. That's a significant amont of case volume that could change the pressure curve pretty drastically still. Maybe there's a bughole load at peak pressure.

 

[VinceMule]

Prarie Hunter, Federal brass will show pressure and loose primer pockets faster than another brand, about the same with Nosler.

Copper fouling will be a deal killer in your Axis, clean frequently.

 

[sveltri]

I've recently changed my thinking on seating depth. I used to think that how the bullet engaged the lands and that distance was the same regardless of powder charge. Now I think it it just a way to fine tune pressure with powder charge providing the greatest effect. However, I did just shoot 4x2 shot groups last night (just shooting the rest of my virgin brass) and the different seating depths certainly showed on paper. Now I'm not sure what I think.

 

[Phil Rizzo]

If the "good" groups are over an inch, you have a mechanical issue in the rifle to work on still, or the bullet/powder match is not suitable. Sucks if you have a lot of components, but fighting a mismatch is begging to be frustrated. What does it do with factory ammo?

Personally if I got a discount rifle shooting about an inch with Red box bullets I'd call it good, stop messing around with lead development, and shoot more/further.


Yes. Group C isn't a "massive outlier" because if he repeats this same ladder test four more times there's a decent chance the other groups open up to a similar average, and even that C shoots a decent group somewhere in there. So far the rifle has shown to be at best 1.1MOA capable, and that's being generous assuming he can get repeatable results out of one of the other groups.


I know you're being sarcastic because Will said nodes are a myth, but the truth is that three shots at a time resulting in these 1MOA+ groups aren't telling him anything other the rifle isn't capable of much better than an inch right now. Tuning happens after major issues are solved. At 1MOA+ there are major issues that hide the result of load tuning. This is a 7mm-08 not a 30-375 Weatheryby, the base precision of the rifle should be better than what those groups show. If he comes back and says the rifle shoots bugholes with facotry ammo then all I'm seeing here is component mismach.

If he comes back as says factory ammo does about the same groups as this, that's what the barrel can produce. It's a Savage Axis II, not a benchrest rifle. I wouldn't waste time chasing the load any further and would start using the heck out of it how it is.

Caveat - he should find the max load for the combination. If he's still 2 grains under need to go up and hit the top and see what happens there. That's a significant amont of case volume that could change the pressure curve pretty drastically still. Maybe there's a bughole load at peak pressure.

I'm asking a question that I don't know the answer to.
trying to learn what satisfies statistical needs and precision needs, based on his requirements with a 300yd hunting gun.

 

[PrairieHunter]

If the "good" groups are over an inch, you have a mechanical issue in the rifle to work on still, or the bullet/powder match is not suitable. Sucks if you have a lot of components, but fighting a mismatch is begging to be frustrated. What does it do with factory ammo?

Personally if I got a discount rifle shooting about an inch with Red box bullets I'd call it good, stop messing around with lead development, and shoot more/further.


Yes. Group C isn't a "massive outlier" because if he repeats this same ladder test four more times there's a decent chance the other groups open up to a similar average, and even that C shoots a decent group somewhere in there. So far the rifle has shown to be at best 1.1MOA capable, and that's being generous assuming he can get repeatable results out of one of the other groups.


I know you're being sarcastic because Will said nodes are a myth, but the truth is that three shots at a time resulting in these 1MOA+ groups aren't telling him anything other the rifle isn't capable of much better than an inch right now. Tuning happens after major issues are solved. At 1MOA+ there are major issues that hide the result of load tuning. This is a 7mm-08 not a 30-375 Weatheryby, the base precision of the rifle should be better than what those groups show. If he comes back and says the rifle shoots bugholes with facotry ammo then all I'm seeing here is component mismach.

If he comes back as says factory ammo does about the same groups as this, that's what the barrel can produce. It's a Savage Axis II, not a benchrest rifle. I wouldn't waste time chasing the load any further and would start using the heck out of it how it is.

Caveat - he should find the max load for the combination. If he's still 2 grains under need to go up and hit the top and see what happens there. That's a significant amont of case volume that could change the pressure curve pretty drastically still. Maybe there's a bughole load at peak pressure.

Thanks. For reference, this rifle produces 3-shot groups of 0.5 to 0.8 inches as the best I've tested. The best factory loads were Federal Fusion 140's @ 0.8", and the Nosler Custom 140 accubonds @ 0.5". I have gotten groups as tight as 0.6" with the Hornady 154's and Varget, but am playing with H4350 to see if that is better. I don't like paying $60+ per box of 20 hunting bullets, so I am experimenting to find an acceptable load for the hundreds of 154 Hornady's that I have.

Believe me, for the purpose of my 7mm08 rifle and what I use it for, any of those sub-MOA groups would do the job (inside 300 yards). I'm not a good enough shooter or interested in bench shooting or I would be asking about fine-tuning a load for my custom Blue Mountain 7 PRC instead of my cheap Savage!

 

[FireFlyFishing]

I know you're being sarcastic because Will said nodes are a myth, but the truth is that three shots at a time resulting in these 1MOA+ groups aren't telling him anything other the rifle isn't capable of much better than an inch right now. Tuning happens after major issues are solved. At 1MOA+ there are major issues that hide the result of load tuning. This is a 7mm-08 not a 30-375 Weatheryby, the base precision of the rifle should be better than what those groups show. If he comes back and says the rifle shoots bugholes with facotry ammo then all I'm seeing here is component mismach.

I've had groups like that in load development with single digit SDs. I wouldn't have known that without a Chrono though. Knowing that my powder charge is spot on, I could then move to seating depth testing/tuning while still keeping an eye on my velocities. Bingo…tight groups. You don't need a Chrono for load development, but it sure speeds up the process.

Yes, I've listened to the Hornady podcast. I understand their points and their statistical approach to load development. I don't, however, get wrapped around the axle with it though. I still develop and shoot tight groups with my handloads.

 

[Bob Wright]

With a chronograph recording every shot within each group it will tell you plenty. Group C was probably a velocity issue. Less so in the other 3 groups. I am so reliant on that speed data, I can only guess here. Just how I do every load development.
Group A and B could easily be a trigger pull issue, if you new the bullet speed variation was minimal. Beg, borrow or steal a chrono.

 

[Varmint Hunter]

My experience with ladder tests is limited. However, I did notice that I could repeat a ladder test on a subsequent outing and get different results. It's often hard enough to interpret a ladder test, but when identical tests result in different info than you have really nothing to go by.

 

[memtb]

Many will not agree with what I am about to suggest…..and perhaps not.

With any rifle, other than one that has a "match grade" barrel, I hand-lap the barrel …..before anything else is done.

This generally can't hurt a barrel, only improve it. Once the lapping is done, then the shooter can work on the plethora of other things that can affect it's grouping ability, bedding, free-floating or not, all things properly tightened base/rings properly aligned / torqued, action bolts properly torqued…… I like to use Loc-Tite to keep everything at the value at which I torque it!

The goal……eliminate as many negatives or variables as is possible. Then, start on load development…..with that chronograph previously mentioned. JMO memtb

 

[willfrye027]

According to my load development, definitely not a fairy tale.

Let's see your results. How about 10 shot groups "out of" the node and a 10 shot group "in" the node. 20 would be better but we can work with 10.

 

[willfrye027]

Will Frye, how many different 20 shot groups should he shoot, and specifically, at what charge weights to determine the best charge weight?

And for a hunting gun only, at 300yds or less, could he shoot less than 20?
say 5 shots or 10 or ?

There is GOOD quality evidence that precision does not change in any meaningful way with incremental charge weights, until you are at/above max pressure. Check out what Brian Litz is writing about and what hornady has done with accuracy fixtures and massive group sizes.

Personally, in the last 15 or so loads I have developed what I do is a single shot working up until pressure signs, over a chrono. Seated to fit mag length or whatever length is out of the lands.

10 shot group at a grain or so below pressure.

If it shoots, you're done. If not, change powder and repeat. If you've tried a couple powders, change bullet.

This, plus understanding normal distribution and having realistic expectations for group size, has mostly eliminated reloading headaches and surprises. No more "I found the perfect node!" Only to have it shoot poorly on the next range trip.

FWIW my hunting rifles are 1.0-1.5 moa for 10-20 shot groups.

It's a can of worms to open up but has been enlightening to take a deep dive into this subject.

 

[Phil Rizzo]

There is GOOD quality evidence that precision does not change in any meaningful way with incremental charge weights, until you are at/above max pressure. Check out what Brian Litz is writing about and what hornady has done with accuracy fixtures and massive group sizes.

Personally, in the last 15 or so loads I have developed what I do is a single shot working up until pressure signs, over a chrono. Seated to fit mag length or whatever length is out of the lands.

10 shot group at a grain or so below pressure.

If it shoots, you're done. If not, change powder and repeat. If you've tried a couple powders, change bullet.

This, plus understanding normal distribution and having realistic expectations for group size, has mostly eliminated reloading headaches and surprises. No more "I found the perfect node!" Only to have it shoot poorly on the next range trip.

FWIW my hunting rifles are 1.0-1.5 moa for 10-20 shot groups.

It's a can of worms to open up but has been enlightening to take a deep dive into this subject.

I use 100yd targets to get my scope on, 300 for load data and 500 for verification. Beyond that is play time on steel normally.
It allows more room for dispersion and separation, at distance. So I think.

What distance do you normally use for load development and proofing?
I'm wondering how others do the process, not claiming mine is the best.