burn rate
- Thread starter roaddog1
- Start date
do you mean 4198? If so, same number but NOT the same powder... Do not substitute H4198 for IMR4198 at the same charge weight!
On the 2015 Relative Burn Rates list published by Hodgdon, IMR4198 and H4198 are next to each other but that does not mean that they can be substituted for each other at the same charge weight.
The staff at Hodgdon are very helpful. You can always call for free advise and information: 913-362-9455
f.y.i. Some powders are identical but numbers don't match. Example: H414 is Winchester 760
On the 2015 Relative Burn Rates list published by Hodgdon, IMR4198 and H4198 are next to each other but that does not mean that they can be substituted for each other at the same charge weight.
The staff at Hodgdon are very helpful. You can always call for free advise and information: 913-362-9455
f.y.i. Some powders are identical but numbers don't match. Example: H414 is Winchester 760
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Being beside each other on the chart just means there isn't a powder between the two; it doesn't mean they are very close. There is no way to tell how big of a gap in actual burn rate there is.
It's similar to saying Bob came in 1st place in the race and Dave came in 2nd. For all we know they could have been 1ms apart or 1min apart in the race; all we know is the order.
I have swapped IMR and H 4198's before in cast bullet loading. In that instance you are using greatly reduced charges so even if one is a little faster than the other it isn't that big of a deal. Going from 2/5 max pressure to 3/5 max pressure is still safe. If you are talking full power loads the difference in burn rates could possibly take it over the max rated pressure.
One way to check is to find load data for the two powders in question for the same weight bullet in the same cartridge. In this case if I look at 7.62x39 with a 125gr bullet we see:
H4198 - 24.5 to 26.5
IMR 4198 - 22.6 to 24.0
The starting load for H is above the max load for IMR. The IMR powder is producing lower velocity with higher pressure with less powder. This tells me it's somewhat faster.
If we look at a different combination; 308 Winchester with a 150gr bullet and H/IMR4895. The starting loads are only 0.4gr apart. This tells me these two are closer (but swapping them is still a risk).
It's similar to saying Bob came in 1st place in the race and Dave came in 2nd. For all we know they could have been 1ms apart or 1min apart in the race; all we know is the order.
I have swapped IMR and H 4198's before in cast bullet loading. In that instance you are using greatly reduced charges so even if one is a little faster than the other it isn't that big of a deal. Going from 2/5 max pressure to 3/5 max pressure is still safe. If you are talking full power loads the difference in burn rates could possibly take it over the max rated pressure.
One way to check is to find load data for the two powders in question for the same weight bullet in the same cartridge. In this case if I look at 7.62x39 with a 125gr bullet we see:
H4198 - 24.5 to 26.5
IMR 4198 - 22.6 to 24.0
The starting load for H is above the max load for IMR. The IMR powder is producing lower velocity with higher pressure with less powder. This tells me it's somewhat faster.
If we look at a different combination; 308 Winchester with a 150gr bullet and H/IMR4895. The starting loads are only 0.4gr apart. This tells me these two are closer (but swapping them is still a risk).
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Very well explained Lutnit
I have burned about 20 lb of each of the 4198 powders over the years, much in the 222 Rem and straight-walled rifle cases.
They are slightly different in burning rate, but in my experience, unless you are running a pretty warm load in a small case,
it would be hard to get into trouble by substituting one for the other.
That being said, cautious and judicious loading practices demand that one start lower and work up, even when changing lot numbers of one specific powder.
This means that if you went from IMR 4198 to H 4198 [or vice versa], you should always work up your load from a lower value for safety.
Regards, Dave.
They are slightly different in burning rate, but in my experience, unless you are running a pretty warm load in a small case,
it would be hard to get into trouble by substituting one for the other.
That being said, cautious and judicious loading practices demand that one start lower and work up, even when changing lot numbers of one specific powder.
This means that if you went from IMR 4198 to H 4198 [or vice versa], you should always work up your load from a lower value for safety.
Regards, Dave.
All powders have a wave of pressure, build up and then decrease. The pressure wave is extremely important mainly to semi autos. A good example is the Garand which needs to have a powder that has the correct wave, which IMR4895 has. And if you decide to use different powders which have a different pressure wave you need to get an adjustable regulator to control it so the gun doesn't get over taxed by the different pressure build up and blow itself up over time. That is your wave. A spike is an extreme climb whereas a wave is a build up to a high point, more gradual( softer ) than a spike.
Sorry. These two powders come from different companies and have different compositions.
But, 4895 and 4064 have the same composition and the difference is the grain structure, with 4895 being much finer.
Only meaningful burning rate chart I was able to find is from Eurenco Bofors.
Their chart provide relative velocity rate and relative pressure for each powder on the list so you can actually compare powders to each-other.
Their ballisticians tested the same powder charge (43.2 grains) using the same bullet (143-grain FMJ) loaded in the 308 Winchester - they used IMR 4350 performance as a reference. This chart may not be any more accurate than any other but, compared to most, it does give significantly more information about how the relative burning rates were derived and it does relate to at least one real-world situation.
Another one is Lapua's chart which gives you side by side comparison in respect to burning velocity of each powder.
Their chart provide relative velocity rate and relative pressure for each powder on the list so you can actually compare powders to each-other.
Their ballisticians tested the same powder charge (43.2 grains) using the same bullet (143-grain FMJ) loaded in the 308 Winchester - they used IMR 4350 performance as a reference. This chart may not be any more accurate than any other but, compared to most, it does give significantly more information about how the relative burning rates were derived and it does relate to at least one real-world situation.
Another one is Lapua's chart which gives you side by side comparison in respect to burning velocity of each powder.
