What, If Anything, Can Be Learned From One Tuned Load to Another?

[Dimner]

So I really don't know how to phrase this question properly. So bear with me.

If I have a rifle, not a benchrest rig, but a custom barrel, custom action, in a McMillian stock, bedded properly, and all that. And I have a fully tuned load that I am happy with that shoots 1/2 moa at distance... 300 yards. So I'm happy with Load A, but I want to start to tune another called Load B

Have you seen anything reflected on Load A's target that can be used as a clue to where to focus the tune when beginning Load B. Load B using the same brass and primer but different powder and bullet.

The variables I'm looking to discuss are

Seating Depth (without getting into an argument of how to measure the lands)
Neck tension (in the sense of using the nomenclature of 0.002, 0.001, etc)
Some other variable I have not considered?

I'm looking to tap into the probably combined 250-500+ years of load development experience on this site. Imagine how many successful tuned load experiences are available for consideration! We talk a lot about how load tuning works in theory, but the actual target is the end all decision maker. For similarities between Load A and Load B, my brain tells me the answer is 'nothing'. Or at least that's the theoretical answer. However, the targets always tell a different story than what 'should be'. So that's what this thread is about. Actual observations.

So I'm wondering if anyone has seen anything in practice, meaning on the target, where there has been some indication of similarity between two tuned loads on the same rifle.

Or have you never seen it happen even once? Or have you seen false positives?

 

[BoydAllen]

So I really don't know how to phrase this question properly. So bear with me.

If I have a rifle, not a benchrest rig, but a custom barrel, custom action, in a McMillian stock, bedded properly, and all that. And I have a fully tuned load that I am happy with that shoots 1/2 moa at distance... 300 yards. So I'm happy with Load A, but I want to start to tune another called Load B

Have you seen anything reflected on Load A's target that can be used as a clue to where to focus the tune when beginning Load B. Load B using the same brass and primer but different powder and bullet.

The variables I'm looking to discuss are

Seating Depth (without getting into an argument of how to measure the lands)
Neck tension (in the sense of using the nomenclature of 0.002, 0.001, etc)
Some other variable I have not considered?

I'm looking to tap into the probably combined 250-500+ years of load development experience on this site. Imagine how many successful tuned load experiences are available for consideration! We talk a lot about how load tuning works in theory, but the actual target is the end all decision maker. For similarities between Load A and Load B, my brain tells me the answer is 'nothing'. Or at least that's the theoretical answer. However, the targets always tell a different story than what 'should be'. So that's what this thread is about. Actual observations.

So I'm wondering if anyone has seen anything in practice, meaning on the target, where there has been some indication of similarity between two tuned loads on the same rifle.

Or have you never seen it happen even once? Or have you seen false positives?

I think that we need a little more information about your theoretical second load. Same powder? Same bullet? What you are trying to accomplish? Your question may be too broad to get useful answers.

 

[Dimner]

I think that we need a little more information about your theoretical second load. Same powder? Same bullet? What you are trying to accomplish? Your question may be too broad to get useful answers.

It's in the OP, different bullet different powder.

However, I should add that 1/2 MOA @ 300 is the goal for the 2nd load

 

[BoydAllen]

It's in the OP, different bullet different powder.

However, I should add that 1/2 MOA @ 300 is the goal for the 2nd load

Sorry about that. Sometimes, when someone writes a book I have been known to skim a bit. To answer his question, I would do a complete load workup from scratch.

 

[Doom]

Changing bullet and powder is a new workup.

EDIT: GLAD I AGREE WITH @BoydAllen!

 

[Bill Norris]

Group formation does play a role in tune as Mike Ezell has stated here many times but not sure one load could be judged by another or could be used to help figure out what the changed load would look like on paper.

 

[K22]

Any time you change the powder and bullet it is a new ball game, especially the bullet, at least that has been my experience. I just have not found any short cut to the dreaded process of load development when seeking varmint grade precision.

With regards to the two variables you mentioned, seating depth can be a significant issue if you change bullets especially with different ogives, I think that is fairly obvious to anyone. I have not done any extensive testing on bullet tension. For me, as long as it is relatively consistent, I have obtained good results for my purposes, but I have a set of dedicated cases for each rifle and rotate their use which I believe helps consistency.

 

[Dimner]

Starting from scratch isn't really the question. I'm always going to start from scratch, because I have OCD and I will never leave any variable untested (for the most part).

Again, this is about what you guys have seen on the target.

 

[BoydAllen]

Starting from scratch isn't really the question. I'm always going to start from scratch, because I have OCD and I will never leave any variable untested (for the most part).

Again, this is about what you guys have seen on the target.

All that I look at when working up a load is the target, so I still do not understand your question. I have a question for you. What is your exact load workup procedure? In my case, I seat very lightly into the lands, do a powder charge investigation, and them play with seating depth. A friend who uses tuners for many of his rifles does the same thing with the tuner turned out a half turn and when he has the load as good as he can without touching the tuner, he works with it to see if he can improve his results. BTW, in February, at a sanctioned group match, my friend shot a 100yd. HV agg (average of five, five shot groups) of .1398, and while that does not beat the NBRSA record, I believe that it is better than the IBS and European records.

 

[Dimner]

My load development goes:

1. First, create a goal velocity range and accuracy requirements
2. Find the 'lands' with my stoney point tool. subtract 0.020" as my starting COAL.
3. Test powder and bullet with two powder charges. Usually Max book load minus 1 or 2 grains, and then the second load is minus another grain. (these values change based on cartridge capacity) This is to compare the velocity I am getting vs what the book or my software tells me I should get.
4. Plug in velocity in software to get a pressure and burn rate estimate. Start over at # 3 if I cannot reach my velocity goals.
5. Develop a test plan for 5-7 loads in appropriate increments. Increments depend on what class of case capacity type cartridge I'm testing. Increments somewhere between 0.3gr to 0.6gr
6. Execute test and look for horizontal stability. Retest if there is any doubts.
7. Using the horizontally stable powder charge, develop OAL test. I use +/- 0.004" increments from my starting COAL. I'll usually go upto 0.004" off my 'lands' measurement and go down to 0.045-0.050.
8. If #7 results in a tune that meets my accuracy goals, I'll verify the tune again to make sure it repeats.
9. If I do not find a good tune in #7, and it is far off my accuracy goal, I'll start over with a new bullet.
10. If I do not find a good tune in #7, and it is reasonably close to my accuracy goal, I proceed with neck tension testing.

But again, I'm not going to be changing how I tune a load.
Let me ask a different way...

After you have tuned two loads from scratch on the same rifle and you get what you are looking for, have you ever seen any similarities on the target as to what the rifle likes?

Has anyone seen it?

 

[Bc'z]

editing... to answer Boyd's question..


Let me ask a different way...

After you have tuned two loads from scratch on the same rifle, have you ever seen any similarities on the target as to what the rifle likes?

It's more like unsimilarities that will cause you to lean towards 1 tuned load versus another.
Let me explain
I recently switched brass, powder, primer in 6br but kept same 105 Bart's
It shoots good, but now I need to shoot it against my old load.
I'm only going to load and shoot the 1 that shines the best.

 

[mgunderson]

Yes and no. It really depends on caliber, cartridge, and general approach. I have seen some bullet changes like the same seating depth. Even switching brands. Switching powder often suggests a similar speed ( plus or minus 50 f/ sec).

Sometimes it all falls apart. Typical for 223 is not typical for 7 magnum. I get the feeling you are playing with a br. If you are smart enough to find differences in neck tension.... try a different load. You will figure it out.

 

[Jager]

I'd agree with the comments above that suggest a new bullet and powder requires a new workup. Pretty much end of story.

But, broadly speaking, there are a few parameters that usually are going be seen in good, tuned loads. Things like a high case fill percentage and having all propellant burnt before the bullet exits the barrel.

Expansion Ratio (the volume of the chamber and bore relative to the case capacity with a seated bullet), something that changes with different brands or lots of brass and different bullet seating depths, is something to pay attention to.

And, finally, Muzzle Pressure (pressure on the base of the bullet when it exits the bore).

In a given rifle, good loads will see a commonality across these factors a lot more often than not-good loads.

 

[NZ_Fclass]

There's 2 reasons for me. 1) Improvement - can I make a good load even better ? 2) With possible supply issues I like to have alternative loads - different powders and projectiles ready.

 

[BoydAllen]

Most shooters that I know would not change both powder and bullet if they had gotten good accuracy with one combination. They might test another bullet with the same powder, or a different powder with the same bullet. Some time ago, I asked a multiple record holding 1K BR shooter who was shooting a Dasher at the time (pre BRA) at what seating depth he usually found his best accuracy. He told me that it depended on the barrel but usually somewhere between six thousandths into the rifling and six thousandths out. At the time I believe that pretty much all of his work, based on earlier experimentation was with one bullet and one powder. I think that he probably uses the method that Alex Wheeler has discussed and recommended for finding touch. My friend who shot the agg. that I mentioned uses very simple and straightforward methods to tune. He knows that the competitive life of barrels is relatively short, so he chooses to be as efficient as possible with his load development. It works.

 

[Homerange]

In my somewhat limited experience compared to many here, there is little you can take from one good load to develop another especially when drastic changes are made like using a different powder and/or projectile.

I've blindly stumbled on a good load or 2 and worked up others however even just changing the projectile to another of the same weight can turn everything to poo.

You might have a great good shooting platform that just likes to be fed a certain cocktail and you need accept and live with it.
As others have said, start again from scratch..... and when you have that pet load, stock up large on the consumables.

 

[searcher]

The changes "on target" that are seen when changing loads (different bullet) in a particular rifle can vary a LOT. It depends on a number of factors. For example, a .375 H&H Magnum is a caliber that is known for the ability to shoot bullets of different weights in the same relative point of impact, however, most guns and calibers will not. Some barrels will shoot a fairly wide range of bullets with a particular powder - like any bullet from 50 to 60 grains, for example. Just because of the difference in barrel harmonics, it would be normally expected to see your grouping move on the target when changing bullets, especially in different weights. But when it comes to group size, you usually have to do the ladder test to find that 1/2 MOA or whatever you are looking for. And it might require the changing of powders for a new bullet before you are pleased. I have a .223 that requires four different powders to obtain 3/8" MOA with four different bullets. I have another one that will shoot most any similar-weight bullets into 1/2" using the same powder. In doing load development, I often try as many as six different varmint bullets in one day out of a new barrel. Rarely do the groups center in the same place - and rarely are they all accurate - even though the barrel is capable with what it likes.

 

[Ccrider]

There are some general things that I look for and expect to carry over, but more often than not, they don’t.

The only way I am comfortable that I have the best load is going through my process, flawed though it may be. If I can’t get the gun to shoot going through my process, I know I have not skipped any fine detail or adjustment that often effects the target results.

The same lot of bullets, barrels, brass and powder, chambered the same with the same reamer, should shoot close to the same tune from barrel to barrel. The more you change, the more likely you will have to put more into working up the load.

Otherwise, if you are looking to short change load development, good luck.

 

[Texas Solo]

If your going to change bullet & powder, you should only change one at a time.
Change only bullet & play with the seating depth. Compare that to load #1.
Then go back to original bullet and change powder, again working the load in .3gr increments. That's the only way to see what each change does.
After all that, pick the best #2 powder charge combined with the best #2 bullet depth and see what you have.
This is the only way that I see to compare #2 to #1.

 

[Dimner]

So the general consensus is that no one has seen much on the target (actual results) that points to any similarities "likes" or preferences between Load A and Load B. And if there were any similarities, they may have been coincidental.

Although, I do whole heartedly agree with @Jager on the details with Fill and Burn percentages. I always do my best to start my loads with those two variables within my own preferred range. 90%+ Fill and 98%+ Burnt if I can swing it. I have found nice loads outside of those ranges, but I have found more stinker loads than good loads outside of those ranges.

I'm okay with nope being the answer.

Like I said in previous posts, I'm always going to do a full tune on any load where I change one or two variables. There was no "question behind the question" with my original post. My mind wanders when I prep brass while putting together a 2nd load for a rifle of mine. I am starting the load from scratch like I always do, and I thought to myself. I wonder if there is some anomaly that those who have tuned dozens of loads may have witnessed.

Just thought there might be an outlier somewhere. Some sort of result on the target that you experienced fellas see from time to time that goes against the prevailing logic in load tuning.

I really appreciate everyone's answers.