Do we trust Gordon's Reloading Tool?

[Creigh]

I loaded my new .243 win with the min and max figures from the powder manufacturer in mind. Also listened to someone who hunted with a. 243 for almost two decades.
Today I had a dedicated reloading guy at my favorite gun shop spin up a session on Gordon's and I was shocked to hear I was 6 grain low on my charge weight. The recommended load was way over the max value from the powder manufacturer.
Obviously the manufacturer has conservative values for a reason and Gordon's seems to be taking a very detailed approach to the powder's make up, but 6 grains?! And Gordon's tells me I'm still in the safe zone with its value.

Do I take the risk and load over the manufacturer max value?

 

[Inline6]

I use it all the time, I would double check what is entered into the program.

What powder are you trying to use with what bullet?

Always error on the safe side of things, not replacement for common sense.

 

[cajunchefray]

I use it all the time, I would double check what is entered into the program.

What powder are you trying to use with what bullet?

Always error on the safe side of things, not replacement for common sense.

I cross reference at least 3 published loads from powder or bullet companies, then compare to online data.
I work within the average data. Some online data has some outliers. I seek to, in a statiscal sense to eliminate the outliers on the bell curve, and work within the mean.

if I want more velocity, outside the mean for a given cartridge, I go to a bigger cartridge.

 

[Inline6]

I cross reference at least 3 published loads from powder or bullet companies, then compare to online data.
I work within the average data. Some online data has some outliers. I seek to, in a statiscal sense to eliminate the outliers on the bell curve, and work within the mean.

if I want more velocity, outside the mean for a given cartridge, I go to a bigger cartridge.

It's not all about velocity, the tool helps you find accuracy nodes. That saves components and range time. Also helps with projected velocities. It is very useful tool.

 

[RLL]

With conventional bullets I’d say they are close. Even CEBs model well. Gordons and quickload both do not estimate loads with Hammer bullets very well in my experience.

Either way, I start conservatively and work up to pressure signs slowly.

 

[JimP]

If you read the fine print on any and all loading manuals either printed or on line you will read that you need to work up your loads and that they take no responsibility for what you do.

 

[Alistair]

Do I trust Gordon's Reloading Tool?

Yes, to a degree. It's a useful resource.

However, it is quite sensitive to the variables entered, as you'd expect, and if you don't understand what data it references, how those variables interact, and ensure that the assigned values line up with reality, then it is not accurate, and can be dangerous.

I DO NOT trust the 'default book values' assigned in all cases. Not without checking them myself. I've seen case capacities a long way off reality in several cases as an example.

I also DO NOT simply take a Gordon's load as gospel, assume it's safe, load it and then shoot it. I wouldn't do that process even with a book max load in a respected manual without testing, and the Gordon's system is a lot less conservative (i.e more accurate) than many traditional manuals. You still need to work up from the low end, and assess for yourself.

Is loading over book max an issue? Maybe, maybe not.

I've loaded plenty of rounds outside book values, but only after careful testing with my components in my rifle. Book values represent values that are almost certainly safe in almost all rifles in almost all conditions. That's a great starting point for your development, and manages liability for the manufacturer. It does not however tell you what is 'safe' in your rifle, and staying within them MAY leave safe performance on the table. It's also possible that the 'max' for your rifle is in fact below 'book max'. I've seen more of the first scenario than I have of the second, but I have seen both.

For your specific question, well.

Six grains above book max is a lot of extra powder in a .243, so my immediate gut feeling would be that they've assigned the wrong powder density figure in the database, or that the user incorrectly assigned a value somewhere. I would be very cautious going that high and I'd certainly start much, much lower within book values and work my way slowly up the charge ladder before trusting it.

Who knows though, once you test it, you may find that Gordon's is correct.

 

[cajunchefray]

I cross reference at least 3 published loads from powder or bullet companies, then compare to online data.
I work within the average data. Some online data has some outliers. I seek to, in a statiscal sense to eliminate the outliers on the bell curve, and work within the mean.

if I want more velocity, outside the mean for a given cartridge, I go to a bigger cartridge.

 

[HWL]

QL and never look back.

HWL

 

[Creigh]

QL and never look back.

HWL

Can't get in South Africa.

 

[Creigh]

Thanks for the common sense replies.

Yeah online data seems wildly off some times. I'll put up the screenshot of all the details. All the inputs look okay to me, the only question mark is what they believe the behavior of the powder to be. I'd like to know if they got those details from the supplier or was it a product of their own testing. Then batch numbers come in to play. All the inputs are accurate, maybe the Pt temperature of the env the powder in is on the low side.

The thought did occur to me that maybe they give loads based on where the maximum percentage of powder is burnt. So like keep going until you reach 100% kind of thing.

 

[Creigh]

I use it all the time, I would double check what is entered into the program.

What powder are you trying to use with what bullet?

Always error on the safe side of things, not replacement for common sense.

Check the attached image for those details.

 

[Tex .416]

Reloading manuals and software are general guidelines. The only truly correct answer is the rifle in your hands.

Each combination of components and the way they are put together, each barrel, how the chamber is cut, and ambient temperature are a lot of variables.

Learn and heed the early signs of excessive pressure.

Velocity is one indicator of pressure.

As one example, I mainly hunt deer with a MRC .308, while my wife uses a custom .308. We both use the Barnes 130 TTSX at 3100 fps. My rifle needs 47.5 of Varget, which is below max in that rifle. Her rifle hits 3100 at 45.3 grains with all other factors the same. Her rifle has a sticky bolt at 46.0.

Computer programs and reloading manuals do not pick up those differences.

Watch the chronograph and your brass and stop at the first hint of excessive pressure.

Again, the only correct answer is the rifle in your hands.

 

[Creigh]

...

For your specific question, well.

Six grains above book max is a lot of extra powder in a .243, so my immediate gut feeling would be that they've assigned the wrong powder density figure in the database, or that the user incorrectly assigned a value somewhere. I would be very cautious going that high and I'd certainly start much, much lower within book values and work my way slowly up the charge ladder before trusting it.

Who knows though, once you test it, you may find that Gordon's is correct.

I'm loading Somchem S365 (local) 35 gr charge weight with a 100g Hornady Interlock.

I plotted some lines on a graph based on charge weight vs f/ps to get a general idea of the speed I'd get with my powder selection. I expected I could get a good feel about what speeds to expect when pushing to the max figure. Now I trust this output for other reasons and perhaps I'm out by 40 f/ps either way because the powder manufacturer tests on a 24" barrel, but if was serious about the accuracy of the graph I would crono this load to compare. Gordon's tells me I'm at 2400 f/ps with my load where I think I'm around 2700 f/ps, assuming the relationship between speed and powder is linear. It might not be but only by a small amount imo.

I've highlighted some of my preferred loads by adding either the speed I want or the load I want.

243, Hornady 100g SP, Somchem S365

www.desmos.com