Relationship Between H 4350 and IMR 4350

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Although not new to reloading by any stretch, I have yet to figure out the relationship of these two powders. Some manuals give heavier loads for H and some give heavier loads for IMR. Looking through all my manuals that show these two powders for various suitable cartridges, there seems to be no rhyme or reason to the data. It would appear to me that there is probably more difference lot to lot than there is in actual burn rate.
Anyone who has extensive experience with these two powders have any insight?
I have extensive experience with many cartridges and IMR 4350 and know pretty much what to expect, but the H stuff isn't acting like the IMR stuff does at all.
 
I've noticed the same with listed max loads as well...not sure why???

I do know the H is a lot more temperature stable though. :)
 
IMR is listed as a bit faster burning on any powder burn chart I've seen. IMR kernels are like firewood logs, H is much more svelte. I wouldn't just jump right to using ones data for the others, but it's usually close enough to use as a starting point. They are definitely different powders though, which is easy to confirm visually. I stopped using IMR since it doesn't meter as well as H, and H is more temp stable.
 
Douglas, no one is in a better position than you are to make a test. Why don't you load up each and then tell us the velocities. .
 
I used to do some consulting work with IMR and in the process developed a good library of their inside information.

IMR powders had (probably better now) a significant variation from lot to lot. So when Nosler tested with their 180 gr bullet they actually had a different IMR 4350 than Speer when they tested with their 180 gr bullet.

Powders are made to a recipe, just like baking a cake, but each lot is a bit different. A certain burn rate is considered the "canister" grade that we buy in the little 8 pound jugs. The faster and slower lots are sold commercially as Fast 4350 or Slow 4350. The commercial buyer buys all 2000 pounds and develops the load for the specified velocity for that caliber/bullet.

Changes in lot number speed are annoying when we finish one jug and open the next. If you have a Chrony, it is not difficult to load and test a half grain more and less to see what best matches the last load. Some of the "change" in lot speeds is the fact that your can of powder dries out a bit over the time you use it, so it changes speed and will be different than the next can.

As for the difference between H and IMR, and manual to manual, forget it. All the book does it get you into the ball park for a Start load. The difference between rifles is HUGE and much larger than the difference between manuals and powder brands.

Open tha can, start with the Start load, and work up. (Just like it says in the book.) And your millage WILL vary.
 
Found this little gem in an old handloaders digest.
"It took handloaders nearly twenty years to find out that IMR 4320 is slower than IMR 4064--most of the time."
 
billdick said:
I think AKA Ron would be the best guy to ask
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Are you sure you don't have your name backwards......................:d:d

Actually I've been expecting "Sunray II" to grace us with his infinite wisdom.............:rolleyes::rolleyes:

The problem Bruce, is that in some cartridges it lists higher loads of H and in others it lists higher loads of IMR and different manuals differ as to which powder you use more of as well..........I'd have to do load tests for 20 or 30 different cartridges, with both powders to learn anything. I'm getting too old for a test this long, hell I can't finish the projects that have been going on for years now............I also hear what you're saying about 4064/4320, different capacity cases will sometimes change the burn rate relationship between two similar powders.

Ganderite........I hear what you're saying and I know all that stuff, I just wondered if there really is a definitive difference, other than temp sensitivity, between the two. I see it all the time with H 110 and Win 296, but I have used so much of these two that I know they are in fact the same powder and the differences in the manuals are merely differences in the lots.
 
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With IMR and Hodgdon being owned by the same company, I wonder if it is possible to talk to someone at the company (other than customer service) who might know?
 
Yep HM2, I have all the burn rate charts as well but the manuals do not correlate consistently with the charts as to which is actually faster or slower, in different cartridges. It seems to me these two are one of those handloading anomalies like 4320/4064 that Bruce mentioned. I suspect that these two jump back and forth, as to burn rate relationship, depending on lot and case capacity. It's all so confusing........think I'll just go back to bed, maybe the answer is written on the inside of my eyelids........:):)
 
Here's my 2 cents. When I first got into shooting and reloading for my 300WM years ago, I started out with my Dad's reloading equipment. He reloads for his 300 so it was easy to learn from him. His goto hunting round was a 180gr Nosler partition with IMR4350. That's the powder I started with. After some reading, Hodgson's extreme powders caught my eye. I went grain for grain, switching from IMR to H4350. I do not recomend this, but it was a low velocity accuracy load. Once I got into the H4350 world, I haven't looked back. I will admit, I have not done any actual testing between the two different brands, nor do I care to because I found my perfect load using H4350. I think at this point, preference for one brand of powder vs another brand is like chevy vs ford, or vortex vs leupold. If you find something that works well for you, keep to it :)
 
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