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Old September 15, 2020, 06:33 PM   #1
lugerstew
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I hate large conflicting load data

I'm loading for my 243 26 inch barrel. I have already found a couple sweetspots at a 100 yards, for a hornady 105 grain Amax with H4350, 39g and 40.5. I am going to load more to take them out further, i rechecked the Hodgdon site and for the same 1 in 10 twist 24 inch barrel, they say 35 to 37.5 max. My hornady reloading manual for same 1 in 10 twist, 24 inch barrel, they say 38 to 41g max. Like i said i have already loaded these and shot them from 38 to 41g and had no overpressure issues. Why cant these data places stop confusing me?
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Old September 15, 2020, 10:11 PM   #2
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I see the same phenomenon for 6.5 Creedmoor, 130 Nosler Accubond. Hodgdon data for max load using Varget shows 34.9 gr. and 2610 fps. Nosler data max load is 38.5 gr. and 2812 fps. I use 37.6 gr. and it produces around 2775 fps over two different chronographs. The Hodgdon data except for Winchester 6.5 Staball is all pretty anemic for that bullet.

For 100 gr. Barnes ttsx in the 6.5 Creedmoor, Barnes load data using Hodgdon H4350 shows max load of 47.7 gr. at 3222 fps. Hodgdon data shows max load of H4350 at 44.7 gr. and 3133 fps. I used Barnes data, and during load development the Hodgdon data was bogus. 44.7 gr gave me about 2990 fps. My load is 47.0 gr. H4350 and the average velocity is around 3190 fps.

This conflicting data has been explained as being the difference between test rifles. Perhaps that's true. Still annoys me.
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Old September 16, 2020, 12:04 AM   #3
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Quote:
Why cant these data places stop confusing me?
If you are confused, its probably because you have been misinformed about what to expect.

Different guns, different brass different lot# of bullets, powder, primers, you and I don't, and can't have exactly what they used, so our results are slightly different from theirs.

Same goes for each different company testing loads and publishing data.

They aren't all identical. They CAN'T be.

In a way, its like cooking. Every see cooking instructions that include "heating times may vary" or "cook 10 min OR until tender" ??

Every individual "stove" can be different from another. When the difference is slight, the data is useful as a guideline. When the difference is large, well, that's why we say start low and work up...

Most data is similar, because most gun & ammo combinations are similar, BUT, it is a bell curve, and combinations at both ends DO exist.
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Old September 16, 2020, 01:20 AM   #4
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If you had the same gun as used for testing using the same cases, primers, bullet lot number and powder lot number, you might get the same results as the manual.
If you are using a different bullet, it will have different geometry. Powders do very lot to lot.
For safety, and I know I'll be laughed at, I use the LOWEST starting load I can find. I may not fire more than a couple of rounds, but I prefer that to being surprised.
This effect has been reduced over the last decade as all testing by SAMMI is done with transducers that plot pressure vs time and spot any pressure peaks or other problems. So, today, a reloading company might spot a pressure peak outside SAAMI limits in their tests and thus lower their max load.
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Old September 16, 2020, 06:55 AM   #5
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I’d try the lower data first and if I get what I’m looking for then that’s the end. If not, then I’d very carefully work up using the high point of the previous data up to either the max recommendation or when first encountering pressure signs.
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Old September 16, 2020, 07:21 AM   #6
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Quote:
Originally Posted by lugerstew View Post
I'm loading for my 243 26 inch barrel. I have already found a couple sweetspots at a 100 yards, for a hornady 105 grain Amax with H4350, 39g and 40.5. I am going to load more to take them out further, i rechecked the Hodgdon site and for the same 1 in 10 twist 24 inch barrel, they say 35 to 37.5 max. My hornady reloading manual for same 1 in 10 twist, 24 inch barrel, they say 38 to 41g max. Like i said i have already loaded these and shot them from 38 to 41g and had no overpressure issues. Why cant these data places stop confusing me?
In addition to using different cases and primers, there is a large difference in cartridge over all length between the Hornady and Hodgdon reloading data. Hornady loads the 105 gr A-Max to 2.630 inches, while Hodgdon loads it to 2.760 inches, a difference of 0.130 inches. There is likely to be differences in the bullet jump to the rifling in each test barrel that affected the maximum charge for each load. What cartridge over all length did you use?
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Old September 16, 2020, 07:28 AM   #7
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reload

Reloading is a long process and lots of paperwork.

Make sure your brass vis-a-vis headspacing is correct for your rifle.
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Old September 16, 2020, 08:44 AM   #8
lugerstew
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My COAL was 2.710, and for my headspacing i always use my fireformed sample as my chamber size, and then resize all my brass .002 less. I know most books are different, its when the difference is like this one of over 3.5 grains, or ones max is the others starting point that gets irritating, I'm not really confused about the idea of all the tests are done with different rifles and conditions etc, i fully understand that, and I ususally try to find the low start data and go by that. I think ive heard it recommended before on here, but in general, what is the best reliable data, the one from the bullet manufacturer, or the powder manufacturer?
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Old September 16, 2020, 09:56 AM   #9
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If one source says 41 gr is a max load, and another source says 37 gr is max all that means is that one tester stopped testing at 41 gr and another stopped at 37.

Few of the companies testing loads push them until they find the max safe load. Just until they reach a point where they accomplish their goals.

That said, I don't like to load above what the book says. But anytime I see things like this it is almost always OK to use the data showing more powder. The key is to always start low and work up. I really like to use a chronograph and watch velocity as I work up.
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Old September 16, 2020, 10:54 AM   #10
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Quote:
The key is to always start low and work up. I really like to use a chronograph and watch velocity as I work up.
+1

Caution combined with common sense and a awareness of over pressure signs goes a long way
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Old September 16, 2020, 02:44 PM   #11
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Many of you already stated the sources of variation among the testing conditions that relate to the barrels, the primers, etc.

Of course, there is also the variation among different lots of powder and changes in temperature, especially with non-extreme powders.
QuickLOAD warns that there might be as much as 10% variation in powder lots.
That range might be at the extreme probability but over the years, several manufacturer have modified their powder mixes while keeping the same 'name'.
Some of the data in manuals is years old and could be out of date for the current powder mix. I think Sierra's Volume 5 was published at least 9 years ago.

And, since most of us don't have the luxury of testing the pressure, we really don't know when we're at Pmax.
Many of the manuals creators don't have the equipment to test pressure either so their determination of max load is based upon whatever indicators they choose to use.
Berger's manual uses QuickLOAD for its data so there is no testing at all.

Personally, I don't trust my personal observation 'pressure indicators' all that much, although I have documented signs of pressure in my 6.5mm Creedmoor rifles when I attempted to get a bit more velocity than was available with loads under PMax - primer flattening, headstamp flattening and tight bolt release. Those signs were obvious and expected because QuickLOAD had warned me that I was loading over PMax and the signs proved them right.
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Old September 16, 2020, 05:35 PM   #12
lugerstew
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I totally agree as well with using a chronograph, ive developed hundreds of pistol and rifle loads, and my initial testing is always with a chrono, it helps give me an idea of where I am according to all my manuals and online data. Thanks for all the responses, i think what I conclude from this, is in the end, I am ultimately responsible for the round I develop, by keeping good records, using a chrono, starting low and carefully working up. I have had a few hard bolt lifts and ejector marks on my brass, when I see those, I stop and take them home and disassemble them and record the results. It appears I need to do a little more work studying load data before jumping into it, because I don't like finding out after Ive already loaded and shot some test rounds, that somebody else's data says I'm over by 3 or 4 grains.
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Old September 16, 2020, 06:07 PM   #13
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Don't the vendors all use the same universal receiver and 24" test barrel?
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Old September 16, 2020, 06:28 PM   #14
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Quote:
Don't the vendors all use the same universal receiver and 24" test barrel?
No. For example, 223 Rem:

Hodgon uses the 24" barrel in a universal receiver.
Hornady uses a Remington 700 26" bbl
Barnes data shows a Wiseman 24" barrel. Not sure what receiver.

[edit] Oh, I see the wiseman is a pressure test system.
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Old September 16, 2020, 06:48 PM   #15
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QuickLOAD warns that there might be as much as 10% variation in powder lots.
that might be a bit overcautious, but it hurts nothing.

Last I knew, different lots of cannister grade reloading powder were allowed to vary UP TO 3%. More than that, that batch wouldn't be sold under the usual number/name.

That being said, sometimes things were worse. I can remember a time where there were 3 different burn rates of H110 on the market, and max loads differed by more than 3%. Further complicating the matter was that if there was data about which lot# did what, it was not well communicated.
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Old September 16, 2020, 09:21 PM   #16
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It's common to see several people shooting the same rifle and ammo have a few dozen fps spread in velocity across them.

They will also have different range zeros on the sight.
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Old September 16, 2020, 11:00 PM   #17
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I had to look those numbers up my self and sure enough the OP is correct . Why does it sound like I'm surprised , because this is the first time I've ever seen Hornady data be much higher then pretty much anything else . I've seen it close to others but never seen it way over others . It's pretty much known in the reloading world that Hornady is pretty conservatives when it comes to it's charge weights . I read somewhere that some have questioned some 30-06 data Hornady put out in there most recent manual , wonder if this is another one that needs looking into ???
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Old September 17, 2020, 06:25 AM   #18
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Quote:
Originally Posted by lugerstew View Post
I totally agree as well with using a chronograph, ive developed hundreds of pistol and rifle loads, and my initial testing is always with a chrono, it helps give me an idea of where I am according to all my manuals and online data. Thanks for all the responses, i think what I conclude from this, is in the end, I am ultimately responsible for the round I develop, by keeping good records, using a chrono, starting low and carefully working up. I have had a few hard bolt lifts and ejector marks on my brass, when I see those, I stop and take them home and disassemble them and record the results. It appears I need to do a little more work studying load data before jumping into it, because I don't like finding out after Ive already loaded and shot some test rounds, that somebody else's data says I'm over by 3 or 4 grains.
This is it pretty much in a nutshell.
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Old September 20, 2020, 07:39 PM   #19
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For safety, and I know I'll be laughed at, I use the LOWEST starting load I can find. I may not fire more than a couple of rounds, but I prefer that to being surprised.
I am not laughing at all. I have my own approach, but that said, lowest is the safest.
Not a thing wrong with that.

Many times I have been sorry when I was not safe (working or play) but I have never been sorry when I was safe.
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Old September 20, 2020, 09:43 PM   #20
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44AMP is right on the money. When I make Gumbo, it's never the same because there is always variance in the preparation, ingredients, and seasoning. 50 years of reloading has taught me the same. Rifle, barrel, twist, bullet lot, powder lot, primer lot, brass lot, bullet depth, neck tension, etcetera, etceteraaaahhhhh. I have manuals from every manufacturer and a subscription to Loaddata.com. They are a guide. Now, I don't use Hornady data if I'm shooting other brands of bullets. I mostly shoot Hornady bullets in my later years and I confess that I use their powder choice recommendations on 243, 260 6.5GR, 280, 7MMRM, and 308. Have found loads that shoot great, have low SD and ES on the Chrono.
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Old September 21, 2020, 12:51 PM   #21
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Manuals reflect the conditions on the day of the test, using the exact components and firearm only. Even environmental differences(temperature, humidity, etc) on the day of the test matters. And it's entirely possible the data found in any manual, even the most recently published manual, was tested years and years ago.
"...vendors all use the same..." Nope. Hodgdon's site shows they used a 1 in 10 twist when 1 in 9.125 is "normal" for the .243.
"...brass vis-a-vis headspacing..." The brass has nothing to do with headspace.
The number of rounds loaded without a chronograph is probably in the billions if not more. How do you think we reloaded before they became cheap enough for anybody who wants one could?
QuickLOAD is not a manual. It's a computer program. Far too many variables that may or may not have been programmed into it.
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