IMR powder vs H-XXX powders...Difference?

covert1 · May 1, 2014

So I haven't understood this, what is the difference say, between IMR powders and a H-designated types.
Example: IMR 4198 vs H4198. Are these completely different with separate load data.? I can't see why they would name these so closely similar.

Trailboss · May 1, 2014

They are intended to be similar burning powders but are manufactured by different companies and are not guaranteed to be the same. Stick with one or the other for load development.

Benchrest · May 1, 2014

Covert1

Always start with published loads, and a simple check of any reloading manual will show any differences between two similarly named powders.

Sabertooth · May 3, 2014

.257 Roberts using H3031 ran out and used IMR3031 using same bullet. Shot group went from 1/2 in. at 100 yards to 5 in.
I used the amount of powder sugested in my reloading book to get the same muzzle volecty.

rick benjamin · May 3, 2014

Sabertooth
Glad you and your gun are ok.

There isn't any mention of "H3031" in any of my manuals.
Wondering what powder-bullet data you were using for 257 Roberts?

My favorite all-around rifle powder is IMR-4064.
I use a chronograph to compare and chart my reloads.
I shoot a box of factory loads over the chronograph to benchmark the gun.

Darkker · May 3, 2014

Trailboss has you on the correct path, but the rabbit hole is much deeper than you think...

Hodgdon has only ever been a surplus blender/reseller, and the WILL NOT tell you what their nominal production tolerances are. So depending upon how the powder was built (is it blended lots of surplus, or a contracted production run), it will vary. Hodgdon has also switched suppliers a few times.
IMR no longer builds their own powder either.
So the practical answer is: even if it is the same powder (only talking say IMR 4895) is the next lot really the same thing?

best defense · May 4, 2014

Most loading manuals have a burn rate chart somewhere close to the front of the book for reference.
Normally all of the different powders they used in any of the formulas in the book are listed in the burn rate chart.

The difference between an IMR and an H (Hogdon) powder can be significant, and should not be interchanged unless there is already a recipe for both of those in the book you are using.

If you do not have a reloading manual, you can look online to find a recipe if you go check out sites like Hogdon has put up. I think there are other powder companies that do the same, but Hogdon is the one I use the most.

AMProducts · May 6, 2014

A few years ago Hodgdon bought out the IMR and Winchester brands, and have consolidated them all under one roof. I'm not sure if they still offer the hodgdon equivalents, but yes there can be substantial differences between the two powders, I encountered this on more than a few occasions where we developed with "3031" and then went into production and got radically different results (nothing destructive, but found the load would no longer shoot accurately) and when we went back to trace the problem we found out that our lab sample was H3031 and our production lot was IMR3031.

Now as far as what's what... IMR4198 as sold in the US is made by ADI (Thales), how do I know? Because when I order bulk quantities the box says ADI on it. IMR3031 is manufactured by Expro (General Dynamics, Canada).

In reality, there are three sources of powder you are likely to find in the US, ADI (Thales, made in australia), Expro (General Dynamics, Quebec) and Saint Marks Powder (General Dynamics, Florida). ADI makes extruded double base powders, Expro makes single base extruded powders, and SMP makes ball powders. These are marketed by Hodgdon (sold as Hodgdon, IMR, Winchester) and Western. So it's likely that you may be buying the same powder marketed under two different trade names from either Hodgdon or Western.

I was just checking ADI's website, and they have a handy powder interchange chart:

http://www.adi-powders.com.au/handloaders-guide/equivalents.asp

Note: The above chart only covers powders they make, there is no interchange for SMP or Expro powders.

Some of these I know to be dead on accurate, as I've seen the containers they come in from the factory, other's I'm a bit dubious about. I don't think SR4759 (which I've loaded tons of) is the same as 2400, which I also load. But most of the others are spot on.

rick benjamin · May 6, 2014

AMProducts;
Outstanding website! http://www.adi-powders.com.au/handloaders-guide/
Tons of information on a single page!

Gentlemen, we are among rocket scientists!

AMProducts · May 7, 2014

*ahem* I'm actually a rocket surgeon.

Sabertooth · May 10, 2014

rick benjamin said:
Sabertooth
Glad you and your gun are ok.

There isn't any mention of "H3031" in any of my manuals.
Wondering what powder-bullet data you were using for 257 Roberts?

Both loads are reduced loads, Quit running max or hot loads the after the first year I stared reloading, saw no point in it. The load for the .257 was from my father in law who came up with it in the 50's or 60's. He also had some smokin hot loads for the rifle I never use. Just short of primer cratering. To hot for me.
Both

My favorite all-around rifle powder is IMR-4064.
I use a chronograph to compare and chart my reloads.
I shoot a box of factory loads over the chronograph to benchmark the gun.