Home Forums Hunting & Shooting Ask The Gunwriters IMR 4350 & H4350

Whats the difference in these two powders? I assume the load data for one isn't interchangeable with the other. I'm looking at load data for a 300 H&H and H4350 is noted but not IMR 4350.

t's likely to be in another manual. I've seen that often.

GSPfan,
Go to the ADI website: www.adi-powders.com.au
They make H4350 and it's AR2209 here.
Cheers, Jack

Close in burn rates, but not the same powder. I’m no help for 300H&H loads...

I seem to recall reading that one is more temperature sensitive than the other. Can't say for sure. H4350 seems to be more popular in some circles.

I've used IMR 4350 in the 6.5 CM with no issues, but haven't had the chance to do any real comparisons between the two powders.

Paul

IMR4350 is usually quite a bit more temp sensitive then H4350. Then again, H4350 is among the most temp stable rifle powders commonly available.

What bullet are you using? I'd use H4350, if it is listed in the bullet manufactures load manual. IMR4350 is a great powder, but is more temp sensitive. I still use it because I started using it a long time ago and have found some damn good loads with it. When loading for hunting loads, I generally work up my loads in the fall or winter, so there's no issues with the temp stability issue. I've seen more than 100 fps difference with loads worked up in the winter and fired in the summer. That will cause a slight POI shift and bigger spread in group size.

Accurate makes a clone too.
A bit further from the mark if you check the burn rate charts.

YES. I recall Mule Deer saying they are very close and they're similar to 'different lots' of the same powder.
----------------------------

They're NOT exactly the same, approach the loads AS if you changed lots of powder.

MD, correct me If I'm wrong.


Jerry

You can look to 300 WSM data for 300 H&H Ioads.

All I know is the one time I used IMR4350 in my Sinclair powder measure I played hell getting consistent powder throws.

I used it because I had to. Never again.

This is what I do and have for several years now.

H4350 has been the most accurate powder i have used and i use it for several different calibers. never used imr4350 though

Have posted this here and there, and it's also part of Chapter 9 of the Big Book of Gun Gack II, "Different Batches of the 'Same' Powder."

For that I tested all three 4350s in the same .257 Roberts, by loading 45.0 grains of powder with the 100-grain Nosler Ballistic Tip in my Remington 722's 24" barrel. Here are the chronograph results:

IMR4350: 3083 fps
H4350: 2980 fps
A4350: 2917 fps

These were all recent batches of powder. In this test A4350 is closer to H4831 in burn-rate.

Should also comment that the results could be different with another cartridge and bullet, and also that temp-resistance can be affected both by primer choice and powder-charge compression. The primary load I've used for many years in my Mark X Mauser Whitworth .375 H&H uses a maximum (and hence very compressed) charge of IMR4350, and is VERY temp-resistant. In cartridge/bullet combinations where IMR4350 isn't compressed it can be not nearly so temp-resistant.

In this particular test A4350 was the least accurate powder--but the charge could also obviously be increased somewhat, whereupon it probably would be more accurate. Many modern powders result in better accuracy when pushed to the max.

I'm using a Sierra 165gr BTSP. The rifle is a Ruger #1 platform I used for a custom project. I picked the rifle up from the smith yesterday and I'm hoping to find something fairly accurate quickly as I'm leaving Monday for a Antelope and Mule Deer hunt in Wyoming. It would be nice to use the new rifle but if development of a decent load doesn't work out it's not a big deal. I'll look at some data for the 300 WSM as well.

John,
Do you have a "feel" for the relative volume or "packing" of the three 4350s?

Just curious if the key might be on the "the amount of powder that will burn" as controlled by the available oxygen...

There was a test done where the same barrel was chambered first to 300 H&H, then to 300 WSM. In summary, they're pretty much the same cartridge in different shapes.

Hopefully Mule Deer will elaborate. Typing on this phone is distracting me from tonight's episode of Inspector Morse.

Smokeless powder carries its own oxygen.

"At this point, what does it matter??"

Both are out-of-stock!

Glad I have ample supplies. Hope you do, too.

I’ve used the IMR 4350 a lot. I get very accurate results. I have two pounds of H 4350 to try. I need to try Reloader 22 in a few also. It does really fine in a 270 Weatherby. It’s hard to make time.

Enough for complete consumption Mathman?
I dont know the formulas off hand and it's been a while since I played with stochiomitry.
Following up on bits and pieces from another thread

As I understand it, the amount of molecular oxygen available in the cartridge case from air is negligible. The "oxygen" in smokeless powder is provided through an oxidizing agent, namely the nitro groups of the nitrocellulose which accept electrons from the carbon of the cellulose portion of the nitrocellulose. This is similar to molecular oxygen accepting electrons from the fuel in open air combustion of fuels. In black powder, the fuel is the charcoal (carbon) and the oxidizer is the potassium nitrate.

Quote from Mule Deer, "The primary load I've used for many years in my Mark X Mauser Whitworth .375 H&H uses a maximum (and hence very compressed) charge of IMR4350, and is VERY temp-resistant.


I have found the same thing in my 280 Rem with a moderately compressed charge of IMR 7828.

I have used the same load of 46.5 grains of IMR4350 and H4350 behind a Speer 145 grain SPBT in a 7x57 Winchester Featherweight with almost identical results, same POI, velocity in 2800FPS range. 5 shot groups right @ MOA

The boys I hunt with call the 4350’s an old man’s powder.

Have you tried "Endeavour" yet?

I haven't yet.

Both H4350 and A4350 are "short cut" powders, with similar-sized granules. IMR4350 granules are about the same diameter but much longer.

Gunsmith Charlie Sisk performed that experiment, at my request for an article in HANDLOADER. It's probably also mentioned somewhere in one of my books, but can't remember which one. He first chambered a barrel for the H&H, then tried several handloads with different powders and bullets, recording velocity, strain-gauge pressure and accuracy. This was all done on the indoor range he had in Texas ( he's since moved back to his native Kentucky), so temperature was consistent and wind non-existent.

He then rechambered the same barrel for the .300 WSM, using the same throat placement, but obviously having to cut off the rear of the barrel some. He fired the same bullets and powder charges, under the same conditions, and the results were just about exactly the same--including which loads shot most accurately.

IIRC it's in GG1 in the chapter on the 300 H&H. I just re read that and will try some of your load data.

Go to the website and see there....

https://www.hodgdonreloading.com/

Thanks John.
I thought about phrasing my question around powder form factor later...
And that the ease of metering is a rough parallel to packing efficiency...


Thanks.
I found a NATO paper that discussed double base solid propellants (a 42%NC-52%NG mix having about 1,100 calories per gram)

NATO paper on solid propellants

Basically my takeaway was that the preheating zone of the powder breaks the bond between NO2//C&O allowing combustion to start.
Combustion goes in two phases NO2 and Secondly NO oxygenated...
No mention was made of ambient oxygen..

Interestingly though they found that copper and lead salts in addition to carbon black had a positive effect on the NO oxygenated portion of the flame.
This might provide some support for observations of a second shot being slightly faster than the proceeding fouler...

Sorry for the sidetrack....

Yup , maybe .

Call me a retro-grouch , but I've medaled at Camp Perry with IMR 4350 and 3031 using Sierra MatchKings . Ambient temperatures are enough to cause folks to pass out .

Oldmanofthesea,

My understanding from various readings is that by the time the bullet exits, the expanding powder gas is usually pretty oxygen-starved--which causes the HOT gas to reignite due to the oxygen in the atmosphere--which is what causes muzzle flash, NOT still-burning powder granules, as so many assume.

Also, if the powder charge produces enough pressure to be within the general design parameters of that powder, then all (or almost all) of the powder will have burned within a few inches of the chamber. If the pressure never gets that high, then some of the kernels won't burn, often a LOT of 'em. But accuracy can still be excellent, as I've found with various low-pressure loads over the years using easily-ignited powders.

It's when harder to ignite powders don't quite reach the "design pressure" that accuracy tends to suffer--one reason the accuracy of "starter loads" often has no resemblance to accuracy at max pressures.

I bought an 8lb jug of IMR4350 military surplus a few years ago. Loaded up some for my newest toy, a 308 Remington. I used 42grn of the IMR4350 and 168grn bullets. Shot one round and the bolt locked up. got it opened and the brass had no primer and I never found it. Fortunately it didn't burn the face of the bolt. I don't know why and I never fired anymore of that load. After thoroughly cleaning the bore and chamber I fired a 3 shot group with the same bullet and 43 grns of BLC-2. It shot a .4" group and no pressure signs.
Don't know if it was missed packaged or what. First time I tried it and the jug was sealed.

Do you really mean 4350? 42 grains of IMR4895 is pretty standard under a 168 in a 308.

Thanks John I recall that (first 2 paragraphs) from a thread a couple of weeks ago, though I probably had forgotten the "few inches" bit.

Regarding Paragraph-3 (pressure) I was thinking the preheating (from the article) ties into how "hot" the primer is and how much NO2 is available at powder ignition leading to how fast the early burn is.

Anyway thanks for putting up with me as I work through the theoretical side of your many years of real world experience.

Never heard of milsurp IMR 4350.

...

Butch,

Along with that Craigster posted, my understanding is that IMR4350 never was a military powder. It was introduced in 1940, and was partly developed for use in the .300 H&H, which Winchester had chambered in the Model 70 a few years earlier.

Hodgdon sold some of what they eventually called H4831 as "4350 data" powder very early on, because the powder could be safely used with IMR4350 handloading data, since H4831 was a little slower-burning.

It’s like a Dodge diesel, ain’t the fastest, aint the sexiest, but it gets you there.

How appropriate as I hunt with old man calibers. I have no need for a 300 super mag when I have a 300 Savage and a 300 H&H. One of my favorites is a 7X57

There must be more than old men buying this powder if it's sold out.

I'm GLAD...

They will not be competing for MY powder !

I don't use it in everything but it will work it A LOTTA things!

Jerry

In my rifles with 7 mag.,25-06 and .270 The IMR4350 and IMR4831 were slightly less accurate than H4350 and H4831.

I have a couple of pounds of H 4350. You are making me really want to try it!

I guess having big jugs of both signifies a "real old man"...

Get it when you can, load up when you can.

Powder has a really long shelf life. I have vintage H-110 and H-4831 that are 50-60 yrs. old, still shoot like fresh powder. But ya gotta store'em right.

DF

John. ! just got back to this thread. I double checked the jug. It is marked Surplus military IMR4895. Grandson is coming over to load some for his M1 Tanker Garand. I will not use it at this time.
Sorry for the confusion.

Look at the size of your case, any case. Even a 105 Howitzer shell isn't big enough to hold enough oxygen to burn all that powder. Aslo, what little bit of Oxygen is in that case would be consumed probably by the primer. But neither the prmer nor the powder rely on outside sources of oxygen to burn. All the oxygen any smokeless powder needs to burn resides within it's chemical compound. It's like Rocket Fuel. OH YEAH it IS Rocket Fuel!

As far as comparing the 4350s, I've never had that experience but I have with the 4831s. They are very different. Max load of IMR-4831 in my .270 Win.= 57grains. Actually that's the max in my old Speer No. Nine manual. But in my rifle I'm getting into higher than desired pressures of anything over 56.7. That manual states that when you get within a half grain of any max load you need to slow increases of propellant to 1/10th of a grain. I know that sounds anal but if I would have followed that advice I wouldn't have had a sticky bolt and flattened primer, which was what caused me to drop my load down and work slowly up and 56.7 was the magic point. And that all brings up something else that's mentioned on here. A Chronograph is a great tool. If you use it right it can keep you out of trouble. Now we all see people that post unbelieveable Velocities from time. I've posted a few. But when working a load up, if you see a questionably high velocity it should give you cause to check things out. I've had loads that were on the high side that were safe. But like when I was working my .270 load up almost 40 years ago, if I'd had a chrono I would have something that would have told me I was crossing the line. Now my my book says the max velocity for a load is 3000 FPS and my load is over 100 FPS above that, I'm going to stop increases until I conform it's not causing the case head to expand. Usually when that happens I call a load good. Also, if the velocity is swinging over 30 FPS from shot to shot I call a halt to increases. Then I'm backing off a tenth of a grain until it calms down to a dull roar. I'm no ballistician but I've learned enough to be cautious enough to keep from blowing my face off.