IMR 4350, H4350.. are they interchangeable?

[geneackley]

Are these two powders basically the same thing just made by two different manufacturers??? Thanks for any insight,
Gene

[Danatkins8605]

They're close but not quite. Also H4350 is more temp stable

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[Dave Hoback]

I agree. Burn rate, they are on top of each other...H4350 being 1 place slower on the chart. But they do have slight difference in burning characteristics. As stated above the IMR is a “bit” more sensitive to temperature, caliber, case capacity, etc.

As for basic things like the cartridge choice & starting loads, yes, pretty much the same. Every cartridge that works with one will work with the other. But it’s in dialing in a load where the slight bit of difference make itself known.

[Robinhood]

I agree with whats been posted. In a larger cartridge like the 06 case I have shot smaller groups with IMR. The creed likes the H better.

[NF1E]

Both are close, made in Australia and packaged in the US.

[gbflyer]

I don’t know where it is but there was a poster that pulled the MSDS sheets on both and found them identical. I’m no chemist, so that may not matter. As a practical matter I’ve found them to be the same for all intents and purposes.

[NF1E]

We all know the composition is not what counts, it's the packaging and wife's tales that really make the difference.

[Robinhood]

We all know the composition is not what counts, it's the packaging and wife's tales that really make the difference.

Don't forget what you read on the internet...Might be substituted for wives tales.

[NF1E]

Don't forget what you read on the internet...Might be substituted for wives tales.

Yes, and only the wisest of readers would come to that interpretation without assistance.

[Harry Pope]

Yes, and only the wisest of readers would come to that interpretation without assistance.

And what better “assistance” than Hodgdon’s own website? The data below is for the .30-06, clearly substituting data between the two powders could result in dangerous overpressures.



https://i.postimg.cc/PNkDgy0s/4-B66-FD7-E-8186-4-C11-A940-A7-D137-BBE9-A0.jpg (https://postimg.cc/PNkDgy0s)

[charlie b]

Kinda like IMR4895 and H4895. Close but not the same. I kept hoping that Hodgdon would get rid of all the overlap when they took over the IMR line.

Historically they were supposed to be the same powder, made for the military .30-06. But, very slight changes in batches can cause differences in loads. Not an issue for the military contracts. They just work up a load for that lot of ammo that produces the velocity required. They really don't care if the load is a grain different from lot to lot.

But, when sold to us reloaders those slight changes cause more trouble since many folks do not measure their velocities. Which means that, yes, there is a difference in the powders. It may only be half a grain but if you are loading to max or to a specific velocity, then you have to be aware of the differences.

That is also why the powder mfgs recommend a new load workup if you change the lot# of the powder.

[CFJunkie]

charlie b is right and H4350/IMR4350 comparisons are a lot like the H4895/IMR4895 comparisons for the same reasons.

Hopefully, this might provide a bit more background on the differences regardless on whether they are manufactured in the same country:

H4350 is temperature insensitive powder (classified as an extreme powder) - with about an 8 fps change in velocity from 0 to 125 deg F.
IMR4350 is temperature sensitive - with about a 155 fps change from 0 to 125 deg F.
The changes over that temperature are just about linear for both powders (for all practical considerations) so the difference in changes per degree F. can be described as:
0.064 fps per degree for H4350
1.24 fps per degree F for IMR4350.
That rate of change is 20 times greater for IMR4350 than for H4350.
Check the Hodgdon Extreme Powder site to see other comparisons since the impacts can vary by caliber.

The increases or decreases in velocity are the result of changes in chamber pressure caused by the differences in the way the powders burn under different temperature conditions.
They may not be much difference between the two powders at some equivalent temperature (whatever that might be) so the tables that are referenced are valid but those same tables would be totally different at the extreme ends of the temperature spectrum.
When you understand the impact of temperature on the powder performance and if you stray off the temperature used in the creation of the tables, the two powders become very different and the difference increases as you stray further.

The powder tables that are listed in this thread were usually created at a single temperature.
(Most US powders use 59 deg F. as the nominal temperature while European powders generally use 70 deg. F. as the nominal temperature.)

Unfortunately, we all shoot under widely different temperature conditions than that and the two powders have totally different results at different temperatures.
If you are shooting in the American desert in the sun and like to load near Pmax, you may find you could be over pressure with IMR4350 while still well within Pmax with H4350.
If you shoot in the mountains in winter, IMR4350 loads will produce a lower velocity than expected and H4350 will drop only a few fps from what was anticipated.

A personal observation on results with IMR4350 before I was even aware of extreme powders:
In my experience, IMR4350 loads performed great with my 30-06 and .270 Winchester hunting rifles.
I did most of my load development for my hunting rifles more than 10 years ago. Unfortunately, my measured results were made before I got any H4350 powder.
I shot IMR4350 in a variety of temperatures, some groups below 18 degrees F because I needed to know how my hunting loads would perform in the field, and I knew that the velocity dropped when it got cold and added to the powder charge for fall/winter hunts.
I also found I got better results and more consistent groups with magnum primers when it got really cold.
I was unaware of the amount that temperature impacted IMR4350 at the time but now I know that the magnum primers were adapting for the velocity drop in IMR4350.
I got about 12-15 fps more muzzle velocity with the magnum primers at low temperatures and was happy to have more muzzle velocity and more consistent groups sizes.

My more recent 6.5mm CM results with two different rifles tell another story.
With my first 6.5mm 12 LRP, H4350 out performed IMR4350 by about 3% but most of my loads were shot with IMR4340 because H4350 was hard to find and I got it late in my 12 LRP's life. (I had a limited time to tune my H4350 loads but still get slightly better results.)
With my more recent 6.5mm 12 FV, with hundreds of groups to compare, H4350 out performed IMR4350 by almost 13% and the standard deviation among the groups was smaller, indicating that the group sizes with H4350 were more consistent. (Another testimony as to why you can't rely on conclusions without significant statistical samples.)
(Just a note, since I learned the impact of temperature sensitive powders several years ago, I currently adjust all my loads to for the temperature forecast when the loads will be fired and manage to be within 3 to 5 degrees.
That just about eliminates the effect of severe temperature changes making the comparison of performance between temperature sensitive and temperature insensitive powders somewhat more credible.

I hope this helps.
I can now happily report that having kept detailed notes on groups shot over 10 years ago can still support interesting comparisons long after the data was gathered even though those comparisons were never envisioned at the time the data was gathered.

[geneackley]

In March I ordered a 280 Ackley Improved barrel from X-caliber and its due to be delivered in a few days. One of the recipes I found in the reloading manuals calls for H4350... but I can only find IMR 4350 locally right now. I was just wondering if I could temporarily use the IMR powder (with a lower power load) until I can get the right stuff eventually... Sounds like I CAN - if I am very conservative in my approach... Correct?

Thanks.

[CFJunkie]

There is nothing wrong with IMR4350. I hope that I didn't give the wrong impression.

I shot IMR4350 for years with my .30-06 and .270 and never knew of its temperature sensitivity.
I did have access to powder tables for IMR4350, though, but when I was shooting when it was really hot in the summer, I probably was shooting at a much higher pressure than I thought I was.
But since I was usually in the middle of the powder table, I wasn't really in any danger.
If you start with loads near the lower end of your reference table, you shouldn't have any problem.
As with any new load, it would be wise to work up from a lower end starting point.
Sounds like your plan is fine.
If you keep track of temperatures, (and the reference table you are using provides the temperature at which tests were made) you can track the impact in velocity increase or decrease relative to H4350 data using that fps degree factor I listed.

It is just that the loads for H4350 will be a bit off for IMR4350 (even at a starting load) and an increase in temperature with the same powder charge will make IMR4350 a bit more of a hot load than for the H4350 data.
Decreases in temperature will actually have it lose some pressure, so you can be a bit safer if the temps are say 20 deg cooler than the temps listed in the reference table you are using. When it gets colder, I wouldn't worry about it.

[charlie b]

Why not just go to the Hodgdon website and look up the data for your cartridge. It lists both powders.

https://www.hodgdonreloading.com/reloading-data-center

[shagerott]

One can also look at the selected accuracy loads on Nosler data - for instance on 280AI, the start loads of IMR4350 are the more accurate loads for lighter bullets. As the bullet weights are heavier, it gos toward the max loads for accuracy. I have used IMR4350/H4350 start loads for light bullets and switched to H4831SC on the heavies in -06 sized cases.

As CFJunkie mentioned - magnum primers for hunting loads. I didn't want to have a slower load at 20 to 40 degrees F when I usually am building loads at 70 to 90 degrees. Maybe it would have been OK with the std primers but I felt I was gaining some consistent loads for the cold weather hunting using magnum primers.

[GrenGuy]

They are NOT interchangeable. Neither are any of the other 4350’s. We know this because of the obvious differences in the load manuals. Stick with the manuals.

The only powders I know of that are interchangeable, are H414 and Win 760. They are “literally” the same powders.

[lastedtiger]

Why not just go to the Hodgdon website and look up the data for your cartridge. It lists both powders.

https://www.hodgdonreloading.com/reloading-data-center

...Or the Nosler manual
https://www.nosler.com/280-ackley-improved

[darkker]

They are NOT interchangeable.

The only powders I know of that are interchangeable, are H414 and Win 760. They are “literally” the same powders.

Correct, and good man.
IMR 4350 is made by General Dynamics in Quebec, H4350 is made by Thales in an Australian arsenal. AND it gets worse then that, for those who care to go down the rabbit hole of how the world works.

The GD plant in Canada, was torn down and completely rebuilt a few years ago now. Partially due to it being extremely old and worn, and partially to update how things are made and a complete formulation change. There were a few ingredients that landed on the EU naughty list. This new list of ingredients is what Hodgdon is marketing as the "wondrous" Enduron line.

So older IMR branded powders and current are positively NOT the same parent powder. During the rebuilding process, Hodgdon was surfing from various sources, including Rhinemetal. So those were also not "the same" parent powder.

Unless there are no conflicts in the world, and no G is buying ammo, Hodgdon doesn't order and buy powder, they take pieces of lots that failed contract specs. They then blend to what they want, and sell to you. Could be from 2 different lots in one manufacturing run, could be from 10 different lots across several decades old. If you watch governmental auction sites, you'll also regularly find Hodgdon buying various bulk powders that have been surplused and discarded; again for any number of various reasons.

As to the "extreme" nonsense, it's 90% marketing wank. It is true that you can very effectively build a powder to be insensitive, when used in a specific set of conditions. That does NOT mean it is magically a universal property in any cartridge that you want. As a prime example, although Hodgdon won't tell you this(if they even actually know it) Varget was designed to be stable, when loaded as M80 ball ammo in the 7.62NATO. It also works extremely well for folks in the 5.56NATO, however.... Compared to the extremely old BL-C(2) powder (original patent date is the 1930's) Varget is incredibly UNstable. Dr. Denton Bramwell did some very good testing on this exact thing.

H414-Win760-AA2700 are all the same parent powder, but lot differences can make them different. Just like H335 & Blc-(2), Both of those come from WC846. In the roughly (to tired to double check) early 1970's Olin internally choose to voluntarily segregate the 846 batch. If part of the batch had 0.25% less CaCO² acid stabilizers, they called it WC844; but 844 isn't different because anyone planned it that way. ....... So knowing that formula patent is from the 1930's, do you still believe Hodgdon for telling the world for YEARS; that H335 was "designed for the 5.56"? 🤣🤣


Cheers

[yobuck]

Correct, and good man.
IMR 4350 is made by General Dynamics in Quebec, H4350 is made by Thales in an Australian arsenal. AND it gets worse then that, for those who care to go down the rabbit hole of how the world works.

The GD plant in Canada, was torn down and completely rebuilt a few years ago now. Partially due to it being extremely old and worn, and partially to update how things are made and a complete formulation change. There were a few ingredients that landed on the EU naughty list. This new list of ingredients is what Hodgdon is marketing as the "wondrous" Enduron line.

So older IMR branded powders and current are positively NOT the same parent powder. During the rebuilding process, Hodgdon was surfing from various sources, including Rhinemetal. So those were also not "the same" parent powder.

Unless there are no conflicts in the world, and no G is buying ammo, Hodgdon doesn't order and buy powder, they take pieces of lots that failed contract specs. They then blend to what they want, and sell to you. Could be from 2 different lots in one manufacturing run, could be from 10 different lots across several decades old. If you watch governmental auction sites, you'll also regularly find Hodgdon buying various bulk powders that have been surplused and discarded; again for any number of various reasons.

As to the "extreme" nonsense, it's 90% marketing wank. It is true that you can very effectively build a powder to be insensitive, when used in a specific set of conditions. That does NOT mean it is magically a universal property in any cartridge that you want. As a prime example, although Hodgdon won't tell you this(if they even actually know it) Varget was designed to be stable, when loaded as M80 ball ammo in the 7.62NATO. It also works extremely well for folks in the 5.56NATO, however.... Compared to the extremely old BL-C(2) powder (original patent date is the 1930's) Varget is incredibly UNstable. Dr. Denton Bramwell did some very good testing on this exact thing.

H414-Win760-AA2700 are all the same parent powder, but lot differences can make them different. Just like H335 & Blc-(2), Both of those come from WC846. In the roughly (to tired to double check) early 1970's Olin internally choose to voluntarily segregate the 846 batch. If part of the batch had 0.25% less CaCO² acid stabilizers, they called it WC844; but 844 isn't different because anyone planned it that way. ....... So knowing that formula patent is from the 1930's, do you still believe Hodgdon for telling the world for YEARS; that H335 was "designed for the 5.56"? 藍藍


Cheers
Are you saying that old Bruce was selling stuff that should have been labeled ( floor sweepings )? lol