Author Topic: H or IMR? (Read 506 times)

gwindrider1 · « **on:** March 27, 2006, 06:40:22 AM »

I'm hopeful that someone can give me some insight as to which of these powders are the least temperature sensitive. Is there any real difference between the two in comparable canister grades?

Bullseye · « **Reply #1 on:** March 27, 2006, 06:56:51 AM »

Think all are temperature sensitive other than the H's that are labeled as Extreme powders. Actually I think at least one of the IMR powder is an extreme powder since H bought them. Not sure sure which ones have been converted to Extreme Powder, check their websight.

Questor · « **Reply #2 on:** March 27, 2006, 07:27:29 AM »

For 4198 I found that altough the load data was the same for H and IMR, H4198 had considerably more muzzle flash for the application I was using. Apparently they're not the same.

dave375hh · « **Reply #3 on:** March 27, 2006, 08:47:10 AM »

I don't know about the load data, but IMR 4198 is the long kernel while the H-4198 is the newer short cut extreme variety. They don't label it as short cut because there is no long cut in the Hodgdon line. They label the 4831 as short cut because they still make both styles, long & short. All the H-4350 is short cut extreme also.

gwindrider1 · « **Reply #4 on:** March 28, 2006, 03:57:43 AM »

Thanks for the replies folks! My recent interest in this was prompted by a range outing with my .458 Win. one cold afternoon in February. Using a book max load of IMR 4895, I got less than expected velocity over the screens of a reliable chrono. It occured to me that shooting at 15-20 degrees may have produced that effect.

Being somewhat set in my ways, I have relied on IMR powders over my 37 years of handloading, but am now considering other powders which might not be as temp sensitive. Seems that I have heard at one time or another, that the Hodgdon powders were less sensitive to temp variations. One way to find out; I'll pick up a pound of H4895, and give it a try before it warms up too much.

Steve P · « **Reply #5 on:** March 28, 2006, 04:20:35 AM »

I am not positive, SO DON'T QUOTE ME ON THIS. I think a lot of the powders are labelled such due to early market competition. IMR-XYZ came on the market so the other company labelled their similar burning powder to H-XYZ to compete. Because H-XYZ was labelled such, IMR then changed their IMR-abc to IMR-123 to compete with H-123.

H4350, AA4350, and IMR4350 ARE NOT THE SAME!!
H4227 and IMR4227 ARE NOT THE SAME!!
They have similar burning rates, but you CANNOT substitute one for the other without safely working up to your load.

H4831 and H4831SC are same powder with different extrusion length. The longer extrusions of the original cut often hang up in powder measures, funnels, or case necks when loading .22 - .243 calibers. I would not jump from one to the other without working up loads. Density in the case and minute difference in burning rate could change a near max load to over max.

Anyone have better information on this? I think it would make good reading.

Steve

JCM · « **Reply #6 on:** March 28, 2006, 07:59:12 AM »

I'm not to experienced with reloading and this really doesn't apply to what you're asking,........ but I'm really happy with the H4350 that I've tried.

It's the only thing I've tried so far in my 30-06. I'm still working on loads for it,.....starting low and working up..... So far I've worked through 7 different H4350 loads for 150 and 165 grain bullets.

All but 1 load have been under an inch. I'm liking this reloading stuff.....

Take care,
JCM

PA-Joe · « **Reply #7 on:** March 28, 2006, 08:23:59 AM »

In very cold areas you may have to cut the charge a little and use mag. primers!

gwindrider1 · « **Reply #8 on:** March 29, 2006, 03:28:42 AM »

Thanks again for the input! I would not assume a same for same load without working up to it in stages, and I do use mag. primers when lighting off large compressed loads in any cartridge.

One thing that I believe is an advantage with the H powders is the smaller kernel size of the powders. I am only about a year into loading for the .458, and am as frustrated as any of it's owners with the case capacity. It's really not that large of a case to be pushing that size bullet, and it is tough to get enough powder in there without compression. Yes, I vibrate the charged cases to get the powder to settle, but it's still a tight fit. I know that the ball powders settle in, and fill the case more completely, but I have stayed away from them because of the compression/temp sensitivity issue.

Yet another handloading learning experience to go through. Ya gotta love this stuff! :-D :-D :-D :-D