Need confirmation if Hodgdon H4198 and IMR 4198 can be used interchangeably or are essentially identical.

I seem to recall they are, but my memory isn't what it used to be.

Thanks.

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-Bob

No.

But why does it matter to you anyway? You are using the manufacturers load data - right? I.e. you go to Hodgdon for H4198 and IMR for 4198 - right?

The Hodgdon web site burn rate chart lists them as #71 (IMR) and #72 (H) out of 145 powders listed, from fastest to slowest.

Hodgdon owns IMR and Winchester powders. One source for load data.

I know on olde powder there was a slight difference. But now Hodgdon is the maker of both brands, so the answer is MAYBE. Check with them. There was never any difference in IMR4227 and H4227, and there is still a difference in IMR4831 and H4831 and H4831SC, so do not assume anything. Ivan

In many sources they have different data shown for each. In my mind I say it's the same thing. In my reloading, I don't.

Why not just call Hodgdon and ask? That's how we got the info on W231/HP-38 and W296/H110.

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Quando omni flunkus moritati.

My sources say yes, but I wouldn't trust me if I were you.

Hodgdon isn't a powder manufacturer, they are a powder marketer.

I don't care who makes the powder or what they list in their data....................

I still take it with a grain of salt.........
starting or maximum loads.

My chrony has proved to me that the numbers are "Ball Park" with their testing equipment used and the guns that we shoot.

Only data that I sort of like is Lyman and it can be a little far from my figures, also.

I have used large quantities of IMR 4198 over the years in .45-70 and 7.62x39. It works so well for me in both of these cartridges that I would never think of substituting H 4198, no matter what anybody says. Stick with what works for you.

Dave Sinko

Ditto in Lyman's 49th Ed.
Same sequence on another/different burn chart of 114 powders:
#59) IMR-4198
#60) H-4198

Not exactly the same, like 231/HP38. I have used both in 6ppc benchrest rifle. For one thing Hodgen is their extreme series and much less sensitive to temperature changes. They are close but not the same.

The key here is NOT to substitute data. They are NOT the same. Burn rate charts don't tell you squat.

So you go to the Hodgdon site and get load data for each of these powders. That is ONE source, the manufacturer, for the data. They list each of the powders with their loads...what is the problem?

ONE example from the Hodgdon load data for a .222 Remington. They do vary
Cartridge Loads - Hodgdon Reloading Data Center - data.hodgdon.com

50 GR. HDY SP IMR IMR 4198 .224" 2.130"

17.0 2850 37,100 PSI

19.3 3152 49,000 PSI
................................................
50 GR. HDY SP Hodgdon H4198 .224" 2.130"

18.5 2890 34,000 CUP

20.5 3160 44,200 CUP

From what I have read, they used to start with the same basic formula but were different in the final product because Hodgdon specified some final performance coatings (whatever they were) that IMR didn't. Thus there was a slight difference in burn speed. Then when Hodgdon took over the IMR line, they carried on the status quo for a while. Then I read that they were discontinuing the H because the I was more popular, but that they were going to package the IMR powder in Hodgdon branded containers going forward.
My head is spinning trying to figure that one out.

No, they are not the same, but they are close enough in burning rate and characteristics that they are more like different lots of the same powder in spite of the fact that they are made by two different manufacturers on two different continents.

Comparing loads using everything but the different powders will give you different results, the same as changing lots of the same powder. This is why every quality loading data source will tell you to start low and work up. They also tell you to do this when ever you switch lots of components used in an established load.

Hodgdon started in business by buying large quantities of surplus military powders and repackaging them. As the surplus ran out they contracted with various powder companies to make copies of the originals. Sometimes these were very close, sometimes not so much, so each case must be looked at separately. They don't tell you who made their powders, but they usually do tell you where they were made, ie. Australia is the location of ADI, Canada is where IMR is located, and etc.

dla's statement about burn rate charts is good to remember. The charts are based on the powders burn rates in a lab device called a "bomb". The actual burn rates of powders will vary depending on the volume and shape of different cartridge cases, sometimes to the point of changing their relative positions. Also, the powders are listed on charts in a sequential order that only shows how they line up, such as no. 1, no. 2, no. 3, etc.. If they were given a value that showed their true relationship to the next powder it would look more like this, 1, 6, 7, 7, 9, 12, 16, 17...

As you can see from all the above posts, no, IMR4198 and H4198 are not identical although they are very close much in the way IMR4895 and H4895 are very similar but not interchangeable. Most of the data is very close or even the same though. (no, I'm not saying you should mix the data)

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Freedom is never free!!
SWCA #3437

I just went through this myself-I can't find the IMR, Hogdon is available. Hogdon 4198 is a wee bit slower than the IMR version-however, I've got some old burn rate charts that reverse that. That said, you can't use the same data, the Hogdon version also being denser (heavier weight for equal volume) than the IMR stuff-at least in my lots of the two powders.

Oddly enough, a powder measure set for my charge of IMR4198 threw the correct (but different) weight of H4198. PLEASE BE AWARE THIS WAS TRUE FOR MY POWDER MEASURE, MY POWDER LOTS AND MY LOAD DATA!!!!! IT MAY NOT BE TRUE FOR YOUR POWDER MEASURE, POWDER LOTS AND LOAD DATA!!!!! Readers assume all liability for any possible use of this information.

BTW, the Hogdon had better velocity uniformity.

Addendum to the above post:

Powder manufacturers generally work up their data in test barrels specially made to create worst case sceanarios from their point of view: minimum chambers & headspace plus minimum bore & groove diameters. As a result, you will almost never achieve their velocities with their powder charges and they will reach maximum pressures at comparatively lower charge weights. Some powder manufacturers do better than others in producing real world load data.

Hogdon's .223 test barrels being a case in point. Their maximum listed loads for IMR4198 with 55 gr bullets are roughly 2 grains below maximum in multiple load manuals I have going back 40 years. You may wish to bear this in mind while working up loads with H4198 WHILE USING DUE CAUTION. These comments are listed for information purposes only and readers assume all risks and liability.