IMR 4831
- Thread starter Big Bob
- Start date
bigedp51
H4831® & H4831SC®
H4831SC - Ballistically, this Extreme Extruded powder is the exact copy of H4831. Physically, it has a shorter grain size, therefore, the designation SC or short cut. The shorter, more compact kernels allow the powder to flow through the powder measures more smoothly, helping to alleviate the constant cutting of granules. With the smoother flow characteristics comes more uniform charge weights, while the individual grains orient more compactly, creating better loading density. Available in 1 lb. & 8 lb. containers.
http://www.hodgdon.com/extreme.html
H4831SC - Ballistically, this Extreme Extruded powder is the exact copy of H4831. Physically, it has a shorter grain size, therefore, the designation SC or short cut. The shorter, more compact kernels allow the powder to flow through the powder measures more smoothly, helping to alleviate the constant cutting of granules. With the smoother flow characteristics comes more uniform charge weights, while the individual grains orient more compactly, creating better loading density. Available in 1 lb. & 8 lb. containers.
http://www.hodgdon.com/extreme.html
jonbearman
I live in new york state,how unfortunate !
It is the same as regular long kernal 4831 according to hodgdons own powder burn rate chart.How did you arrive at the conclusion it burns faster?
Gary in MD
Gold $$ Contributor
The title says IMR, which is different and faster burning than the Hodgdon powders
Hodgdon's 4831 was one of the company's founder B.E. (Bruce) Hodgdon surplus US government numbers that got this family concern going just after the end of WW2. As with many such powders sold by the late Mr. Hodgdon from his retired railroad boxcar stores on a rented Kansas farm in those early days, individual powder lots varied greatly and were sold as such with a lot number and advice that it was a 'fast' or 'slow' lot. (I read the reminiscences of a handloader from that era who said surplus '4895' could have burning rates and hence max loads that ranged from 1980s IMR-3031 through to 4320.)
In the early postwar period, the large US ammunition and ammunition component companies were opposed to handloading as they believed it threatened their sales, so IMR-4831 was not made available to the retail market for some years, likewise Winchester and Remington unprimed cases, bullets etc. This allowed a new breed of entrepreneurs into the market luckily, the big boys' refusal to play seeing farm and garage based outfits such as Speer, Hodgdon, and Hornady to become established and grow into respected secure businesses by the time that Big Corporation America woke up to the damage it was doing to its reputation and sales.
When newly made IMR powders did reappear on the retail market, Hodgdon's surplus 4831 was nearly used up, but was moreover now very old dating from 1944/45 and had become noticeably slower burning as a result of this prolonged storage. So, the (newly made) IMR version was faster burning than the old 'Hodgdon' originally IMR type - enough to cause serious pressure problems by straight substitution of IMR for H in a maximum load. When I started handloading 30 plus years ago and read every book on the subject I could find whether current or out of date, warnings about IMR v H4831 were normal currency.
In any event, when Hodgdon finally ran out of surplus IMR extruded powders, he and his heirs turned intially to ICI Nobel in Scotland, later ADI in Australia to manufacture replacements. It's said that Hodgdon specifically asked ICI Nobel to mirror the late model surplus powder's slower burning characteristics as his customers had got used to them.
Whether there is a significant difference today is more questionable, but some burning rate charts still list H4831 as a little slower burning.
HOWEVER ................ and this is the crucial part as far as I'm concerned, close or identical relative burning rates on a chart or list DO NOT mean they have the same properties or allow the use of anything like the same charge weights safely. Burning rate is only an indicator of likely suitable application in that something around H110, N110, Ramshot Enforcer suits cartridges with similar needs to heavy .44 Magnum and standard .22 Hornet applications while 4831, Re19/22, N160 etc suit 6.5X55, .284 Win, and .30-06. Having loaded both Hodgdon and IMR versions of 4895, I regard them as significantly different powders in cartridges like .308 Win, the IMR version allowing heavier charge weights before pressure signs kick in and also producing significantly higher MVs. That is despite their often being shown with identical burning rates on charts. Talk to any .284 Win F-Class user and he or she will say H4831 is THE powder for 168s to 180s. Nobody, or at any rate very few, recommend IMR-4831.
So, to go back to the OP's question, IMR and either version of Hodgdon 4831 are different powders but with similar applications and need to be worked up to what will likely be different maximum loads. Charge weights that give the smallest groups in any barrel / cartridge / bullet combination may vary significantly too. So far as Hodgdon H4831 alone is concerned, the company says the two versions give identical performance allowing substitution of charge weights in any cartridge / bullet combination. Since Hodgdon / ADI powders tend to vary a bit, sometimes more than a bit, by manufacturing lot and since one presumes 'standard' and 'sc' cut versions are by definition different lots anyway, I'd always look to go down marginally anyway in this substitution and work back up to get satisfactory results.
In the early postwar period, the large US ammunition and ammunition component companies were opposed to handloading as they believed it threatened their sales, so IMR-4831 was not made available to the retail market for some years, likewise Winchester and Remington unprimed cases, bullets etc. This allowed a new breed of entrepreneurs into the market luckily, the big boys' refusal to play seeing farm and garage based outfits such as Speer, Hodgdon, and Hornady to become established and grow into respected secure businesses by the time that Big Corporation America woke up to the damage it was doing to its reputation and sales.
When newly made IMR powders did reappear on the retail market, Hodgdon's surplus 4831 was nearly used up, but was moreover now very old dating from 1944/45 and had become noticeably slower burning as a result of this prolonged storage. So, the (newly made) IMR version was faster burning than the old 'Hodgdon' originally IMR type - enough to cause serious pressure problems by straight substitution of IMR for H in a maximum load. When I started handloading 30 plus years ago and read every book on the subject I could find whether current or out of date, warnings about IMR v H4831 were normal currency.
In any event, when Hodgdon finally ran out of surplus IMR extruded powders, he and his heirs turned intially to ICI Nobel in Scotland, later ADI in Australia to manufacture replacements. It's said that Hodgdon specifically asked ICI Nobel to mirror the late model surplus powder's slower burning characteristics as his customers had got used to them.
Whether there is a significant difference today is more questionable, but some burning rate charts still list H4831 as a little slower burning.
HOWEVER ................ and this is the crucial part as far as I'm concerned, close or identical relative burning rates on a chart or list DO NOT mean they have the same properties or allow the use of anything like the same charge weights safely. Burning rate is only an indicator of likely suitable application in that something around H110, N110, Ramshot Enforcer suits cartridges with similar needs to heavy .44 Magnum and standard .22 Hornet applications while 4831, Re19/22, N160 etc suit 6.5X55, .284 Win, and .30-06. Having loaded both Hodgdon and IMR versions of 4895, I regard them as significantly different powders in cartridges like .308 Win, the IMR version allowing heavier charge weights before pressure signs kick in and also producing significantly higher MVs. That is despite their often being shown with identical burning rates on charts. Talk to any .284 Win F-Class user and he or she will say H4831 is THE powder for 168s to 180s. Nobody, or at any rate very few, recommend IMR-4831.
So, to go back to the OP's question, IMR and either version of Hodgdon 4831 are different powders but with similar applications and need to be worked up to what will likely be different maximum loads. Charge weights that give the smallest groups in any barrel / cartridge / bullet combination may vary significantly too. So far as Hodgdon H4831 alone is concerned, the company says the two versions give identical performance allowing substitution of charge weights in any cartridge / bullet combination. Since Hodgdon / ADI powders tend to vary a bit, sometimes more than a bit, by manufacturing lot and since one presumes 'standard' and 'sc' cut versions are by definition different lots anyway, I'd always look to go down marginally anyway in this substitution and work back up to get satisfactory results.
bigedp51
Big Bob said:
What is the difference between IMR 4831 and 4831 short cut ?
IMR 4831 is made in Canada at the old DuPont plant, H4831 and H4831SC are made in Australia.
The old DuPont plant in Canada is now owned by General Dynamics Weapons Division. And the Australian ADI powder plant is now owned by a French company.
The two powders IMR-4831 and H4831 share the same roots as the Australian plant was set up by DuPont during WWII. BUT they are now two separate powder companies and only share a similar number. Meaning they are close in burning rate but not identical powders.
The H4831 powders from Australia are one of the "Extreme powders" and designed to be less temperature sensitive than their American counterparts.
IMR-4831 is number 121 on the Hodgdon's burn rat chart and H4831 and H4831SC are number 125.
http://www.hodgdon.com/burn-rate.html
H4831 & H4831SC
I've used only two different lots of H4831SC, compared to too many lots of H4831 to recall - including quite a bit of the old original WWII surplus 4831. In my experience, the SC version is consistently about 2% slower than any of the lots of H4831 I've had. The most consistent & often proved example in my loading experience is in the straight 284 Win with 175-180gr bullets. 54.5grs of H4831 is my max load with moly'd bullets - I get loose primer pockets rather quickly with heavier charges. 2% of 54.5 = 1.09grs, and that's roughly how much additional 4831SC it takes to get the same velocity in this case. However, in most of the 284 bbls I've chambered, I got better accuracy with plain ol' 4831.
As has often been discussed, burning rate charts are not a particularly good reference for determining safe powder charges by interpolation. IOW, burning rate can & will change based on case capacity & expansion ratio. As an example, when comparing H4831 & the SC version in my 280 AI, it takes quite a bit less than 2% more SC to get the same velocity as was obtained using straight H4831. In this case, the 280 AI has just under 6grs more case capacity than the 284 with WW brass. Very similar cartridges, yet different results with these two powders. Which is one big reason I dislike posting load data - too many variables involved, and so many shooters looking for a shortcut in load development. Quite understandable with the component shortages which continue to plague our sport, but not a safe route to take, nonetheless.
I've used only two different lots of H4831SC, compared to too many lots of H4831 to recall - including quite a bit of the old original WWII surplus 4831. In my experience, the SC version is consistently about 2% slower than any of the lots of H4831 I've had. The most consistent & often proved example in my loading experience is in the straight 284 Win with 175-180gr bullets. 54.5grs of H4831 is my max load with moly'd bullets - I get loose primer pockets rather quickly with heavier charges. 2% of 54.5 = 1.09grs, and that's roughly how much additional 4831SC it takes to get the same velocity in this case. However, in most of the 284 bbls I've chambered, I got better accuracy with plain ol' 4831.
As has often been discussed, burning rate charts are not a particularly good reference for determining safe powder charges by interpolation. IOW, burning rate can & will change based on case capacity & expansion ratio. As an example, when comparing H4831 & the SC version in my 280 AI, it takes quite a bit less than 2% more SC to get the same velocity as was obtained using straight H4831. In this case, the 280 AI has just under 6grs more case capacity than the 284 with WW brass. Very similar cartridges, yet different results with these two powders. Which is one big reason I dislike posting load data - too many variables involved, and so many shooters looking for a shortcut in load development. Quite understandable with the component shortages which continue to plague our sport, but not a safe route to take, nonetheless.
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