Minimum loads and lower safety question
- Thread starter Scottish Highlander
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Prof Young
New member
Risk of squibs . . .
Loading below the minimum and you'll risk having a squib. If you don't catch the squib when it happens, the next shot could blow up your gun and do serious harm or even death. I was an "bare minimum" loader when I first started. Made a couple errors and had some seriously dangerous squibs. Fortunately I caught them all before I pulled the trigger a second time.
Live well, be safe
Prof Young
Loading below the minimum and you'll risk having a squib. If you don't catch the squib when it happens, the next shot could blow up your gun and do serious harm or even death. I was an "bare minimum" loader when I first started. Made a couple errors and had some seriously dangerous squibs. Fortunately I caught them all before I pulled the trigger a second time.
Live well, be safe
Prof Young
FrankenMauser
New member
While I understand the reasoning for all of the "don't reduce starting loads" arguments, and agree with it, for the most part...
I must still point out that if you are never "allowed" to reduce charges, then very few of the cartridges that we enjoy today would exist.
Much of what we take for granted today originated as a wildcat cartridge, 20, 40, 60, or 80+ years ago. There was no load data. There were no "minimum" loads. There were simply a bunch of curious individuals trying to create new cartridges to suit a particular need. Many of those guys were using surplus powders. And the "Powley Computer" hadn't even been heard of by most wildcatters.
To figure out what load range the cartridge needed, they made an educated guess, started (very) low, and worked up until bad things happened. (If you don't know what happens at your true 'maximum' then you don't know how far you should stay away from it, either.)
Tonight, I was doing the same.
.475 Tremor + Norma 200 + Barnes 275 gr XPB = ?????
It's a wildcat based on a wildcat (.458 SOCOM), using an uncommon powder, combined with a bullet that has ZERO data for anything even close to this design.
There is no minimum load.
There is no established starting point.
The only known maximum load is the point at which powder overflows the case and it becomes impossible to seat a bullet.
Today, we do have computer programs that can offer reasonably accurate predictions of load performance for many cartridges, and give us powder charge recommendations based on that data. However, .458 SOCOM and its derivatives don't play well with internal ballistics programs, so that's not an option here. Sometimes internal ballistics programs will give a prediction that's 3% high. Other times they'll give predictions that are 15% high (or more!). Which one do you assume that it is this time? 3%? 15%? Somewhere in the middle?
(I've seen QuickLoad give predictions for .458 SOCOM that are physically impossible - there would be 5+ grains of powder overflowing the case, even with a 20" drop tube. And some people still just reduce that by 10% for their starting load, and give it a try...
)
What's left is an educated guess, and trial and error.
In this situation, I derived my data from a previously tested load that used a bullet of the same weight, but shorter bearing surface and larger available case capacity (not seated as deeply).
The difference in case capacity is between 9.6% and 10.3%, depending upon how precise you want to be. I rounded it to an even 10% and reduced the established load accordingly (dropping 4 grains from a 40 gr powder charge).
From experience, I know that the full 10% reduction will not be necessary. But, what I don't know is how much the longer bearing surface (by 0.145") will come into play.
Testing involves running a series of pressure test loads, typically in 0.3 gr increments, from the decided upon 'starting load', on up until something bad happens. I have to know how the cartridge performs through the whole range of powder charges, in order to understand how well it is suited to the load. And I need to know just how bad things get when 'maximum' is hit.
Given that this is based on the .458 SOCOM with a 35k psi max chamber pressure, and is also using large pistol primers (44k psi and they're done), I'm not likely to be experiencing bodily injury.
But, still, I have a mantra for testing new wildcat loads. I repeat it to myself every time: "Please don't blow up. Please don't blow up..."
Even for .458 SOCOM which, although technically a wildcat, does have published load data and quite a bit of (hobbyist-derived) established load data, I end up in the same situation.
My .458 SOCOM has a tight bore, a tight throat, and a tight chamber. As such, my loads for that rifle are actually BELOW published starting loads. (Yes, I got there the hard way. And, in some cases, had to.... start low and work down...)
The loads that I have to run are seen as ridiculously light by most SOCOM shooters (2.5 gr to 6 gr less powder). Yet, if I run half a grain more powder, I show pressure signs.
If I wasn't 'allowed' to reduce powder charges, I wouldn't be able to shoot that rifle.
So, even though the cartridge has been around for 15 years, there is published data, I have a very high quality barrel, and I'm using popular powders and bullets, I still have to reduce powder charges from "starting" loads and chant my mantra when I test something new. "Please don't blow up. Please don't blow up..."
Bottom line:
You can't make hard-and-fast rules about not reducing powder charges.
Every rule has an exception, and this one has many.
I am not suggesting that it is okay to reduce charges of Blue Dot, H110/W296, or super-slow rifle powders. They have been proven to create dangerous (or incredibly unpredictable) situations when used below recommended charge levels. But with run-of-the-mill stuff, dropping a few percent isn't going to be a big deal. With many powders, even reducing the starting load by an additional 10% will only create a dangerous situation if you happen to have a squib and are too ignorant to notice the bore obstruction.
I must still point out that if you are never "allowed" to reduce charges, then very few of the cartridges that we enjoy today would exist.
Much of what we take for granted today originated as a wildcat cartridge, 20, 40, 60, or 80+ years ago. There was no load data. There were no "minimum" loads. There were simply a bunch of curious individuals trying to create new cartridges to suit a particular need. Many of those guys were using surplus powders. And the "Powley Computer" hadn't even been heard of by most wildcatters.
To figure out what load range the cartridge needed, they made an educated guess, started (very) low, and worked up until bad things happened. (If you don't know what happens at your true 'maximum' then you don't know how far you should stay away from it, either.)
Tonight, I was doing the same.
.475 Tremor + Norma 200 + Barnes 275 gr XPB = ?????
It's a wildcat based on a wildcat (.458 SOCOM), using an uncommon powder, combined with a bullet that has ZERO data for anything even close to this design.
There is no minimum load.
There is no established starting point.
The only known maximum load is the point at which powder overflows the case and it becomes impossible to seat a bullet.
Today, we do have computer programs that can offer reasonably accurate predictions of load performance for many cartridges, and give us powder charge recommendations based on that data. However, .458 SOCOM and its derivatives don't play well with internal ballistics programs, so that's not an option here. Sometimes internal ballistics programs will give a prediction that's 3% high. Other times they'll give predictions that are 15% high (or more!). Which one do you assume that it is this time? 3%? 15%? Somewhere in the middle?
(I've seen QuickLoad give predictions for .458 SOCOM that are physically impossible - there would be 5+ grains of powder overflowing the case, even with a 20" drop tube. And some people still just reduce that by 10% for their starting load, and give it a try...
)What's left is an educated guess, and trial and error.
In this situation, I derived my data from a previously tested load that used a bullet of the same weight, but shorter bearing surface and larger available case capacity (not seated as deeply).
The difference in case capacity is between 9.6% and 10.3%, depending upon how precise you want to be. I rounded it to an even 10% and reduced the established load accordingly (dropping 4 grains from a 40 gr powder charge).
From experience, I know that the full 10% reduction will not be necessary. But, what I don't know is how much the longer bearing surface (by 0.145") will come into play.
Testing involves running a series of pressure test loads, typically in 0.3 gr increments, from the decided upon 'starting load', on up until something bad happens. I have to know how the cartridge performs through the whole range of powder charges, in order to understand how well it is suited to the load. And I need to know just how bad things get when 'maximum' is hit.
Given that this is based on the .458 SOCOM with a 35k psi max chamber pressure, and is also using large pistol primers (44k psi and they're done), I'm not likely to be experiencing bodily injury.
But, still, I have a mantra for testing new wildcat loads. I repeat it to myself every time: "Please don't blow up. Please don't blow up..."
Even for .458 SOCOM which, although technically a wildcat, does have published load data and quite a bit of (hobbyist-derived) established load data, I end up in the same situation.
My .458 SOCOM has a tight bore, a tight throat, and a tight chamber. As such, my loads for that rifle are actually BELOW published starting loads. (Yes, I got there the hard way. And, in some cases, had to.... start low and work down...
)The loads that I have to run are seen as ridiculously light by most SOCOM shooters (2.5 gr to 6 gr less powder). Yet, if I run half a grain more powder, I show pressure signs.
If I wasn't 'allowed' to reduce powder charges, I wouldn't be able to shoot that rifle.
So, even though the cartridge has been around for 15 years, there is published data, I have a very high quality barrel, and I'm using popular powders and bullets, I still have to reduce powder charges from "starting" loads and chant my mantra when I test something new. "Please don't blow up. Please don't blow up..."
Bottom line:
You can't make hard-and-fast rules about not reducing powder charges.
Every rule has an exception, and this one has many.
I am not suggesting that it is okay to reduce charges of Blue Dot, H110/W296, or super-slow rifle powders. They have been proven to create dangerous (or incredibly unpredictable) situations when used below recommended charge levels. But with run-of-the-mill stuff, dropping a few percent isn't going to be a big deal. With many powders, even reducing the starting load by an additional 10% will only create a dangerous situation if you happen to have a squib and are too ignorant to notice the bore obstruction.
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