"H" vs "IMR"

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I'm probably going to step into it - probably because there are more experienced people here that know better - but my rifles do not shoot any different between H or I powders.
 
Not a whole lot of difference, at least not with my lots.

According to the reloading manuals, and my own little testing, there are differences. But based on my chronograph data, the velocity differences between the two are not much more than what I would expect in normal lot to lot varience.

If I had a pressure barrel, maybe I could see differences between pressure curves, but I don't have one. So I can tell H4895 is green, IMR black, and H4895 powder particles are a little longer than IMR. For the lots I have. Big whoop.

But....

Powder lots vary, within brand and make. So, if you are shooting loads on the upper end of "hot", you need to be very particular, and not assume you can duplicate charge weights with a different lot of the same powder. You can end up blowing primers.

Both of these powders shoot excellently with 308 and 30-06 cartridges. I highly recommend them for folks shooting M1a's and Garands.


ReducedIMRnexttoH4895.jpg



ReducedIMR-H4895oncard.jpg
 
H4895 is good stuff. I am sticking with that. no need for me to try imr 4895 if i am very happy with h4895.
 
DO NOT try to interchange near Max load data.

It is not the same stuff!

And I had the blown primer & welded shut bolt-action rifle to prove it one time years ago! (Before I knew any better!)

rcmodel
 
Hodgdon powders are made in Australia, IMRs in Canada. Do not assume that the Canadians and Australians can faithfully copy original DuPont or each other.

Use current and brand specific data.
 
you sure jim
my imr trail boss says made in australia
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Since Hodgdon is now the US importer and distributor for both ADI powders from Australia (with Hodgdon designations and labels) and IMR powders from Canada, they can pretty well call the shots. I don't know why they chose to label Aussie-made Trail Boss as IMR instead of H.

Hodgdon is also the distributor for Winchester powders and they get their Spherical powders from the same plant in St Marks, Florida that makes Winchester.

Hodgdon does not own any of these powder mills, all they make in their own facilities are Pyrodex and 777 fakes.

Oh, yes, redneck2, IMR stands for Improved Military Rifle. There were also MR Military Rifle powders before them. They still make some SR Sporting Rifle powders... but in pistol-shotgun burn rates.
 
Even if they were exactly the same before extrusion, the length of cut will change the surface area to volume ratio, and the packing density, so they would end up with different burn characteristics. And that's before the added coating that changes the color, which would also have an effect. Add it all up and you need a pressure barrel to know exactly how they'll perform in any given situation.

Am I stating the obvious?
 
I read an interview with one of Bruce Hodgdon's sons (Bob I believe, not J.B.) on the subject of "ours vs. theirs" during a Shot Show just after Hodgdon purchased IMR in 2003. According to his statements in the interview, the differences are so minor that their internal protocol uses chemical tests (not actual live-fire shooting) to keep each powder consistent in quality control. He said that they could inversely balance the density of the material with its energy content to help keep each powder consistent from lot to lot. But since the published data is based on separate live-fire tests through the universal receiver, he urged that you follow H data for H powder and IMR data for IMR powder.

Have you noticed that the online Hodgdon reloading guide lists the exact same data for W231 & HP38? Also for H110 & W296, etc.? These are instances where the powders are in fact the same. But they don't do that for H and IMR powders, do they?

Each of us should develop our own conclusions based upon reliable published information.
 
The ADI powders, Hodgden's Extreme Powders, are supposed to be less sensitive to temperature extremes. That means the load you produce and shoot in summer @ 90 degrees, shoot nearly the same @ 20 degrees in the winter. The same cannot be said of the IMR powders which can vary wildly from hot to cold days in pressure and velocity and that can lead to changes in poi.

NCsmitty
 
the IMR powders which can vary wildly from hot to cold days
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That must be why they keep making it for going on 80 years or so! :rolleyes:

Why, it's a real Wonderment we could go from beating Rommel in the Sahara desert in WWII, to the "Frozen Chosin" in Korea using that wild IMR powder in every round of 30-06 ammo!

rcmodel
 
ants,
If you check the Hodgdon data closley,when the other manufactures data is provided, you will usually see that the pressures are higher than the Hodgdon powder at the max loads. It is just one way they promote their powder. Yes they give data on IMR ALLIANT and WICHESTER
 
rcmodel, no disrespect for IMR powders, I use them in many of my loads, along with Alliant powders. I just don't let them set out in the sun in the summer and rarely shoot in the winter. I have seen several articles where ambient temperature extremes affects both pressure and velocity in both reloads and factory loads. I'm sure you know this, as a consummate reloader. As I mentioned previously, Hodgden's Extreme Powders are supposed to lessen this effect, but here's a little tidbit from 6mmBR.com review of Quickload.

QuickLOAD Potential Pitfalls--What to Watch Out For

Even with its impressive level of sophistication, and its amazing store of data, QuickLOAD has a few shortcomings. Some of them are far from obvious and a novice QuickLOAD user might not understand the significance of them.

Temperature--QuickLOAD does have a function to adjust loads for ambient temperatures. However, it essentially treats all powders alike, except for the Hodgdon Extreme powders. As to those, QuickLOAD cautions "Do not use with Hodgdon Extreme Powders". Well any seasoned reloader knows that all powders don't react the same to swings in temperature. And we can tell you that even the Hodgdon Extreme powders deliver more pressure in very hot summer conditions, compared to cold winter days.
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So we just try to do the best that we can with what's available. I personally never stop trying to improve my ability to do better in whatever I attempt.
Why, it's a real Wonderment we could go from beating Rommel in the Sahara desert in WWII, to the "Frozen Chosin" in Korea using that wild IMR powder in every round of 30-06 ammo!
Click to expand...
There's no wondering; the US provided it's troops with the best rifle and it's ability to compensate for all environments and shooting the best round.

NCsmitty
 
IMR and Hodgdon differences

The only Hodgdon powder I use is H4350 which burns a tad slower than IMR4350. I tried IMR 4350, but prefer and use H4350 in my fast .243 Winnie loads. A 62 grain Barnes Varmint Grenade left my muzzle at 3489 fps today. I'm trying to hit a steady 3450 fps at 70 degrees, so I'm getting close. Ambient temperatures affect all powders I've ever tried. These Varmint Grenades are really accurate at 3430 fps, like six rounds at a 100 yards into a 3/4" group, and I'm not the world's steadiest shooter. cliffy
 
They are similar but as was said different enough so you should not interchange data.
As a rule powder data is not interchangeable.
I favor IMR 4895 for .308 and .223.
 
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