I NEED A EXPLANATION!!!

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Just because you see max loads listed that doesn't mean that is the max safe load. It just means that is the max load that source tested.

It isn't unusual to see data from source "A" show a max load at one point. Then you find source "B" showing more powder as their max load. There could be several reasons but one is simply that source "A" achieved the results they were looking for and simply stopped testing at that point. Source "B" continued to add powder and keep testing with more powder.
 
To me loading manuals are all over the place, Lee, Hornady, Lyman. I prefer load data from the manufactures. And some of the best info does come from people on these sites that shoot strings and through a chronograph, which I like to use myself.
Data from manufacturers is absolutely the best!

But would that be the bullet manufacturer, the powder manufacturer or the mold manufacturer?

I don't know which manufacturer you're referring to, but as a general rule, I'd trust any of 'em a helluva lot more than I'd trust loads posted by individuals on the internet.
 
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Yes indeed, load data from different published sources can seem to be all over the place. However, within one bullet profile and weight, you should see a trend that lower max charges are used with shorter OAL's. Also, take a look at the test barrel if available. Some will state what model of gun they are using, and the barrel length, some will use "universal receiver". A universal receiver with a 6" barrel will typically show higher velocity than a 4" Smith&Wesson M&P. Some books load to minimum spec Sammi chamber dimensions, some load somewhere between min and max chamber dimensions. This will have an effect on pressure and velocity in a given test platform. That is the main reason one publisher's max load may be very near another's starting load....which can be frustrating when starting out. That's also the reason its important to do a proper work up on any new load, or when changing components for an existing load. Very rarely will there be load data using the exact bullet you have, loaded to the exact OAL you're loading to, using the exact test platform the tester used. That's why its advisable to have several manuals, and between 2 or 3 or more sources, kinda read the tea leaves and get a sense of what range your work up should fall between. Good rule of thumb is to load the longest OAL that will fit your chamber and feed from the magazine. Longer OAL=lower chamber pressure. However, you can go too low and stick a bullet in the barrel. Also, you can go too low and have function problems in autoloaders, or poor accuracy. I find 115g 9mm rounds traveling less than 1050fps from my CZ75 have a tendency to impact high and to the left of my point of aim. Though, on a work up, I'd rather have that than too high of pressure and have a catastrophic failure of the gun
 
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…I don't know which manufacturer you're referring to, but as a general rule, I'd trust any of 'em a helluva lot more than I'd trust loads posted by individuals on the internet.

This. It is normal for different published sources to have differing data - that’s just the way it is for the reasons stated above. Internet forum data is not generally reliable - some is good but some is….terribly dangerous. Never start at the maximum published data, but which one? Answer, the data with your bullet at your overall loaded length.




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All published reloading sources vary. It is just something that as reloaders we have to live with. Reloading is not an exact science and there are multiple factors that play into the amount of pressure created in a load. Some load sources like Hornady are notoriously conservative. This is why we do load workup. You take the data from multiple sources and come up with a reasonable but safe starting load and work your way up checking for pressure signs with each load. Then you come up with the best load for your application. To me that is one of the fun parts of being a reloader.
 
Reloading is an applied science. You conduct your first test "experiment" with the lowest possible charge "risk" and work to a stated goal. My goals are good function and accuracy. I punch paper. Some people need velosity for proper terminal ballistics in hunting or self defense. Loading for a revolver is easier than an auto pistol because in a revolver function is not a requirement. If you have 3 or 4 different charge weights with the same or similar bullet to a close oal use the area they overlap. The middle ground here is the sane choice.
 
Data from manufacturers is absolutely the best!

But would that be the bullet manufacturer, the powder manufacturer or the mold manufacturer?

I don't know which manufacturer you're referring to, but as a general rule, I'd trust any of 'em a helluva lot more than I'd trust loads posted by individuals on the internet.

Why I mentioned that I like the information best from people themselves is I can hear what loads they shoot and see what the manufactures/manuals data showsand then I make my own decision on where to start and work up my loads. let's be real, many powder manufacturers data is usually on the lower safe end. I know this is a fact from using powders like BE-86.
 
My son wanted to load about half of the max powder load, in all four bullets. 115 RN, 124 HP, 124 FP, & 147 RN so we should be safe.

Hopefully we will go to the range Sunday ... Will inspect the cases for things like bulging or cracking but with half the Max load we should be fine. Right?
Any range report from the OP?
 
Just a heads up. None of my 5 or 6 loading manuals had information on a 300AAC. I have a Hornady 9fh edition which lists the 300AAC and the 300 Whisper as interchangeable, and the case length as 1.400. I proceeded to cut and size 100 casings to that size, ran them through the sizing die, and dressed the case mouth. (WRONG)! I didn't have good load data an went searching. Found most of what I needed on SAAMI and the net, and discovered the case length error. Back to cutting and sizing. Obtained a new Lee manual which I now use. Lesson: Just because a manual lists something doesn't make it gospel. Paper doesn't reject ink. Check multiple sources, both loading manuals and manufacturers data. Many of you have said it - start low and work up.
 
Piezo pressure testing equipment isn't quite as good as most people imagine. It will easily give answers 1000 PSI different on samples drawn from the exact same batch of ammunition. So it is not surprising that two different labs following the same process will get different answers, just from random sampling error.

The SAAMI maximum pressure specs include a "finagle factor" to account for sampling error. The 30-06, for example, has a maximum spec of 61,500 PSI in reality. But the number we use is 60,000 PSI to provide a safety margin because we know our sampling system is imperfect.

Of course, there are the other factors mentioned, such as seating depth, bullet geometry, etc.
 
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