Differences between the loading "bibles"

.260 Rem has a case capacity of apx 53.5 grains of water

Hogdon says for H4350 using a 140 gn bullet (Nosler Partition) the min 39.0 max 42.0 142 gn . For 142 gn ( SMK)it shows 41.5 min and 44.5 max

Now the 6.5 CM has a case capacity of 52.5 gns or 1 gn less. For the 140 gn bullet 36.0 to 40.0C (Amax bullet) and the 142 gn (SMK) is 38.8 min and 41.5 gn max.

Now that tells me that is bad data. Now if anyone wants to argue angels on a head of a pin then feel free but common sense says that the .260 Rem data for the 142 is out in left field. Just speaking for myself but I will never trust single source data again
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Now that tells me that is bad data.
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WHY?????


Why does it tell you it's "bad" data??

because it's different? because its not what you expected to see??

My "Common sense" doesn't tell me the .260 data is out in left field, it just tells me that is what they tested and the results they got. Why does your's tell you different??


There is an important point being missed here. EVERYTHING involved, all our stuff, and all the stuff used in the load testing, every bit of it, is physically somewhere within a range of tolerances.

Every component of the ammo, and the fit in each individual gun, can be as identical as we can get it, and STILL BE SIGNIFICANTLY DIFFERENT.


Most of the time, things tend to be generally similar and usually fairly close to the same result, but it's not a given, and its not possible for it to be one.

People are writing about min/max loads, and acting as if they are absolute safety boundaries, and work the same in every gun in the world. They aren't.

It just doesn't work that way.

You've got to understand that the results the testers get and publish are what they got with what they tested. You and I don't have EXACTLY what they tested. Got a chamber that is tighter or looser than the one they used? You're going to get a different range of results. using thicker or thinner brass? using a different lot# of the same powder? Using the same weight bullet but a different amount of bearing surface? or a different alloy jacket? All these, and much, much more will potentially change what you or I get from what they got doing their testing.

Most of the time, its not a significant difference, which is why loading manuals/published data are useful as GUIDELINES.

But, sometimes, tolerances "stack up" in ways to produce very different results from what the testers got.


Blowing primers two grains before reaching a listed maximum load doesn't mean their data is bad, it means YOUR gun and ammo combination is DIFFERENT. Get the chamber reamed and now you can go up to the listed max means you have altered your rifle to be closer to what was used in the test. That's all.

I'm a fossil, turned to stone in the ancient days when we didn't worry about the pressure numbers as much as we worried about the actual results in our guns. And we understood that what you got and what I got, using the same stuff as much as we could, might be drastically different.


These things are NOT linear. XYZ in gun A can give you the same as XYZ in gun B, but it might not. I know I'm beating a dying horse here, but it's something few people seem to understand, based on their questions and assumptions I've been seeing here.

Different guns with identical barrel lengths firing the same ammo can give much different velocities. It happens. Every factor involved can be just enough different between them that widely different results can happen.

Likewise, things can be close enough to each other that the results are essentially the same. There's no way to know which is going to happen until you actually test.

I don't see "bad data" anywhere, I just see data that is different. Might be different enough to not be right for your gun. But it was "right" in the gun they used for testing.

The difference in load data for the .45-70 was mentioned, and tis a good example. Certain guns can take loads that other guns can't handle safely.

Doesn't mean the data itself is "bad" means its only the appropriate data for certain guns, and not every gun.
 
Ok, peoples! Lets get back to the issue of helping Hmonnier with his hadgun powder issue.

Faster powders are ok to use, just depends on what cartridge/ bullet combination.
For example, i use Alliant Red Dot in my 45 ACP for my 185gr LSWC.
What you have to watch is the bullet type, bullet weight, and their listed COAL.
As opposed to rifle cartridges that list Max length, pistol cartridges list Min length. And they differ from manual to manual.
Best to make a dummy round, remove barrel frol you pistol( auto), and see if it drops into your chamber.
And adjust seating depth accordingly. Next check to see if it will fit the magazine. (It should).
 
Since the OP hasn't yet said what cartridge(s) he is looking at loading, here's some general info about powders and speed...

Fast powders give "better" results in smaller cases. In smaller cases they usually can give full power performance.

In large cases, fast powders hit the pressure limit, before full velocity possible is obtained. For example a max load of 231 in a 9mm gets you "full" speed, but a max load of 231 in a .44 Magnum only reaches around 1000fps and several hundred more fps can be obtained with a slower powder in that round.

Another issue with the fast powders and large cases is the possibility of a double charge going un-noticed. A double charge of a slow powder won't fully fit in the case, so its very obvious when it happens. A double charge of a fast powder might only fill a large (.44mag) case halfway, and could be overlooked. Enough pressure to destroy the gun, but not impossible to miss the difference in powder level between 6gr and 12gr in a large case.


The opposite side of the coin is the slowest (pistol) powders and small cases. Doesn't work worth a darn. Powders like 2400, W296 and H110 simply can't fit enough powder in small cases (such as 9mm) to give full regular velocity. Often they will not burn properly, either.


There's no reason to avoid fast powder in some cartridges, and no good reason to use it in some others. Use what works best, where it works best, don't use it where it doesn't, and all will be well.
 
Actually Std7mag the original post is all about minimum and maximum book loads with differing numbers, so my post was dead on subject as far as I am concerned.

@ 4 Amp, if you like those Hogdon numbers it's your gun and face so have at it. I think it is kinda weird though how all the 120 and 130 load data mirrors the 6.5 CM yet the Hogdon number for the 142 compared to the CM jumps 7 or 8 percent. To me that is a red flag

I reran the load test today with a milder charge and got very acceptable groups and SD's, no pressure signs and supersonic to 1000 velocities
 
I say use one book to load by!!! If you don,t like that book loads then use the other book. ONE book at a time
 
hmonnier asked:
"...'should I take the lowest of the max across the different books' as the max load?"
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No.

You should follow proper load development procedures and begin with the Starting Load (if there's a difference between manuals, use the lowest or take a consensus) and then work up incrementally until you get a load that 1) functions the gun reliably and 2) is accurate. Once you achieve this, stop. That's your load.

If you reach the Maximum Load and still haven't achieved reliable function and accuracy, then look to a different powder, bullet or primer and start developing the load again.
 
I think it is kinda weird though how all the 120 and 130 load data mirrors the 6.5 CM yet the Hogdon number for the 142 compared to the CM jumps 7 or 8 percent. To me that is a red flag
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I understand how the sudden dis-continuity for no apparent reason, gives one pause and makes you go "hmmm I wonder why that is???"

But I think that, rather than just saying "its got to be bad data", I think the key is apparent reason.
There is always a reason. In this case, we don't know what it was that caused the difference, and Hodgon didn't say. It's even possible the members of the test staff don't know the reason, but there is a reason.

Why do two guns as identical in all aspects as we can make them shoot the same ammo and show differing muzzle velocities? There are reasons, even if we can't pin them down, exactly.

they report what they got. Sometimes they say why they got what they got, often not. It doesn't have to make sense or be in line with all the rest of the data, if that's what they got, its what they got. It MIGHT be what you or I get, it might not.

years ago I had a rifle that loved a load that was a full grain over the highest listed max I could find in anyone's book. It shot well (which is usually NOT the case with max loads), there were no pressure signs on the case or primer, case life was normal, everything was as good as it ever got with anything. And yet, it was well over book max. For that rifle, and ONLY that rifle, that load wasn't "max".

Had another rifle, cratered primers with everything you put in it, low starting load, factory load, everything showed excessive pressure. And no, it wasn't the firing pin or the hole or any of those parts. It was the chamber. Just a little too tight in the throat, so the case mouth didn't have the usual amount of clearance to release the bullet, which raised the pressure on every load fired. in that case it was something that could be, and was, fixed. But it was just a tiny bit of not quite enough, and within the acceptable tolerance specs (though at the extreme end of the range).


Different things in different guns can cause different results, with different bullets. Apparently there was something just enough different between the rifle and the 142gr bullet and the rifle and the 120 nd 13gr bullets to cause a "weird" result. What it was, they didn't say.
 
Overall bullet length isn't the key measurement in making this comparison.
Given identical cases, seating depth and shank seating depth would be more important when determining pressure differences and where PMax might be.
Incidentally, no one knows if the specs of the cases tested were the same so the volume of the cases can't be compared.

For a 6.5mm Creedmoor according to QuickLOAD, using IMR4350 powder at identical seating depths (2.810) and cartridge trim lengths (1.910)

Hornady 140 grain A-Max #26332 (bullet length = 1.375) would yield 63,060 psi at 44.1 grains of IMR4350 at 59 deg. F. The seating depth would be .475 and shank seating depth would be .325.

Sierra 142 grain SMK #1742 (bullet length = 1.380) would yield 63,501 psi at 44.1 grains of IMR4350 at 59 deg. F. (That is over the 63,091 psi PMax.) The seating depth would be .480 and shank seating depth would be .290. Notice the difference in the shank seating depth between the two bullets.

Just for comparison,
A Sierra 140 grain SMK #1740 (Bullet length = 1.320) would yield 60,416 psi at 44.1 grains of IMR4350 powder at 59 deg. F. The seating depth would be 0.420 and the shank seating depth would 0.230.

A Hornady 140 ELD-M #25331 (Bullet length = 1.380) would yield 63248 psi at 44.1 grains of IMR4350 powder at 59 deg. F. (That is also over the 63,091 psi PMax.) The seating depth would be 0.480 and the shank seating depth would be 0.330. Note that the pressure data looks a lot like the data for the 142 SMK doesn't it.

The deeper placement of the bullet in the case increases the pressure.
Also, a heavier bullet should also increase the pressure with the same loads.

Also the temperatures during the testing weren't listed.
If the temperature during the testing of the 142 SMK was 37 degrees instead of 59 degrees, the pressure at 44.1 grains would drop to 61,288 psi.
At 37 degrees, 44.5 grains of IMR4350 would yield 63,051 psi (just below PMax).
Could be it was colder on the day they tested the 142 SMKs than it was when they tested the 140 A-Max bullets..
 
Sierra 142 grain SMK #1742 (bullet length = 1.380) would yield 63,501 psi at 44.1 grains of IMR4350 at 59 deg. F. (That is over the 63,091 psi PMax.) The seating depth would be .480 and shank seating depth would be .290. Notice the difference in the shank seating depth between the two bullets.
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computer theory is all well and good however in real life I got initial pressure signs at 42.0 grains and at 42.5 grains blew a primer. The Hogdon data uses a 142 SMK for it's 142 gn load data and I am seating between .040 and .045 off lands and shooting in mid 70's temps

I stopped at 42.1 yesterday and my primers were flush but beginning to show initial pressure signs flattening out and getting minor cratering. Pretty sure if I kept pushing just because the book or Quickload said it is ok I would have been splitting cases, blowing primers and taking a chance on having a emergency room visit.

I stopped a full 2.0 gns below what Quickload and 2.5 gns below the Hogdon calls dangerous because I used this thing called common sense. I know that some here won't believe this but sometimes the book is just wrong. Throw out all the esoteric theory in the world and those primers would still look just the same in real life.

Now who am I supposed to believe, the book, the computer program or my eyes ?
 
Hounddawg,

There are a lot more variables that cause overpressure with lighter loads than just powder charges.
For example, a tight chamber will also cause high pressure indications with loads that are far below PMax.
I had a Savage 12 LRP 6.5mm Creedmoor that would show high pressure indications with loads that were close to minimum on the powder tables.
Savage reamed out the chamber a few thousandths and the high pressure indications went away and I can now shoot loads close to PMax with no high pressure indications.

Even if you don't want to believe it, computer simulations based upon measurement data like QuickLOAD provide individuals who want to understand the relative effects of the variables related to powder type, load charges, seating depth, trim length and temperature with information that leads to understanding. Those relationships are all good to understand, but if you don't also consider all the other reasons for variations as well you are just fooling yourself as much as you would by refusing to use information to that is available to increase your understanding.
 
you are just fooling yourself as much as you would by refusing to use information to that is available to increase your understanding.
Rimfire5 is online now
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actually you are the one fooling yourself by believing what the book says over real life results. Books data is not infallible .There is no tight chamber causing over pressure, this was the 4th powder I have tried in that rifle using the same bullet.

Varget, H4831 SC, and IMR 4350 book loads all had normal velocities and no overpressure indications with the same bullet in the same barrel. I tested each one from min to max or near max looking for stable velocity nodes. I never had any pressure issues with any other powder using the book loads until I came to the H4350

baffles me as why anyone is still arguing this other than the sake of saying I am wrong. One poster even went as far as calling me a liar.
 
I don't think you are wrong so much as taking it out of context.

I suspect Quick Load shows a low load as well?

Given the chance I would cross check with my manuals, but those same manuals also disagree and sometimes by two (maybe upwards of 4) grains, that is a lot.

If you start low and work up like you should with any load, you may find that sooner than Quick Load or the highest Manual load showing there be dragons.

Its a guide not a firm, but then so are the manuals.

That is why we start lower and work up regardless of who says what.

So yes in the end you are right that its the real world that counts but that is true for both sources.
 
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