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

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.