i have noticed in some of my new reloading manuals that IMR 4350 in some cases has a higher grain load than H4350 of the same round. i remember 25-30 years ago where it was said that you could use IMR 4350 powder load data to load H4350 powder because the H was slower. but not the other way around. it doesn't look that way now..

Consider those two powders similar but not identical. Personally I would never interchange the data between them (or any two powders). I might carefully work up a little past the published data if the velocity doesn't show like it should but to just arbitrarily use the other data is not recommended. I have always found top charges a little heavier in the IMR version and velocities a bit faster too when compared to the H version (at least in the cartridges that I load for). The H4350 has a deterrent coating giving it it's "extreme" properties and that changes the effective burn rate as compared to the IMR version.

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I have always found top charges a little heavier in the IMR version and velocities a bit faster too when compared to the H version (at least in the cartridges that I load for). The H4350 has a deterrent coating giving it it's "extreme" properties and that changes the effective burn rate as compared to the IMR version.

20-25 years ago H4350 had the heaver load and the higher velocity, and even on todays burn chart, H shows slower than IMR

I get slightly higher velocities with a little less powder using H4350 vs IMR in 6.5CM, 30-06, 308, and 300 H&H. The "H" also seems to endure the wildly fluctuating temps (freezing-115 degrees) where I live better than the IMR. They are both great universal powders across a wide range of cartridges.

Reloading manuals are all over the place from book to book with the same powder and bullet weight. For the exception of a decent starting load, they are otherwise pretty much useless.

Remember that the Hodgdon range of H powders are simply relabeled Australian manufactured powders known as the AR series by us down-under types. The Australian manufacturer originally known as Australian Defense Industries (ADI) produces them as temperature insensitive. They have a good reloading book downloadable online for free with extensive listings of their powders. AR2209 is H4350, AR2208 is Varget etc.

Throughout the years, I have noticed that powders do change their performance, but not enough to worry about it.

This happens even in the same rifle.

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Throughout the years, I have noticed that powders do change their performance, but not enough to worry about it.

Last year I bought a .300 Win Mag. I started working up loads with an old batch of AR2209 ( H4350 ). Got a good load with expected velocity, then ran out of powder. So I bought some new AR2209 and made more cartridges with the same charge weight. Through the Chrony they were close to an honest 100 fps faster ! Alarmed at a possible mistake I carefully loaded more to double check, and again found the new batch gave higher velocity. Well, lesson learnt and have now lowered the charge weight.

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Originally posted by 30.06king:

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Throughout the years, I have noticed that powders do change their performance, but not enough to worry about it.

Last year I bought a .300 Win Mag. I started working up loads with an old batch of AR2209 ( H4350 ). Got a good load with expected velocity, then ran out of powder. So I bought some new AR2209 and made more cartridges with the same charge weight. Through the Chrony they were close to an honest 100 fps faster ! Alarmed at a possible mistake I carefully loaded more to double check, and again found the new batch gave higher velocity. Well, lesson learnt and have now lowered the charge weight.

What you are finding is exactly why ammunition manufacturers do not just load their ammunition for any particular cartridge by powder weight. Often reloaders wish to know how many grains of what powder is used in factory loads and then hope to duplicate this, or they dissect factory ammo themselves to get this information.

It just doesn't work this way and is why manufacturers do not reveal what and how much powder they use in any particular cartridge as it will vary from batch to batch of ammunition as they load these over a period of time.

Manufacturers actually blend their powder to get the ballistics they want. Reloaders could do something similar if they could afford to buy powder in larger quantities and blend all the different batches together to give consistent results over a long period of time.

Very early milsurp 4350 Powder named 4350 DATA powder was actually more simular to that eras H4831 and so marked depending on the year of production for the military as I recall or something like that.

I have a 150 lb. capacity stainless steel lock top container within a heavy wood crate of milsurp 4831 or 4350 DATA..Its the stuff that Jack O'Connor used..I still have about 30 lbs of that stuff..Jacks load was 62 grs. of it for over 3200 FPS in his 270s and in my .270, all fwt Mod. 70s, that's a full case compacted btw..My max load in todays 4350 and 4831 is several grains less. If I use todays 60 grs of IMR-4831 it pushes the bullets out over night enough so as not to fit in the magazine or chamber in some guns, and pressue were low and velocity was high..That old stuff sold for $50. a pound on the black market at one time in the 1950s to maybe the 1960s best I recall, as it kicked up velocity maybe as much as 150 to 200 FPS at about 48 to 50,000 PSI, so I sold about a 100 lbs of mine. I bought it from and old bench rest shooter in twin Falls for a dollar a pound and got that neat container that's used to store oats in today. My 30 pounds transferred to cans. Those were interesting days.

They sold the Mil Surp 4831 in 50lb. cardboard kegs also. I think that we all used a bunch of it. One thing to keep in mind is that the military powder does NOT exactly translate to that which is sold to civilians. The lots that the arsenal's buy is within certain specs but it might not be the same. Lets take for example M852LR. If you want to duplicate it, what you have to do is to chronograph the military ammunition and then using your civilian powder, put enough in your case to get the same velocity. You also have to weigh the Military case. Then weigh your case and get the difference in weight. Multiply that difference by 12% and that will give you a start weight in grains of powder to make up the difference. between the two.
Bye the bye, I went out to the bunker and found two flats of TULA LR primers. I have had such good luck with them in gas operated guns. 210M's are a wee sensitive in that platform.
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