Powder burn rate for reloads?
Andy J.
Thanks,
Andy
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Ronald Shin, PhD
"Andy J." wrote:
# How do you know when to use a fast burning powder or a slow burning one?
Assuming we are talking about handguns, that depends on the caliber, and the
desired properties of your loads.
If you want to save money, you would go with a faster burning powder, since
you use less powder per charge.
In general, the high pressure calibers, such as the magnums and the 10 mm
tend to favor the slower burning powders, such as Blue Dot or AA#9.
Some guns do not reliably function when faster powders are used. I believe
that Accurate Arms mentions this as a warning, that Glocks may not function
too well with AA#2.
If you want to get a higher velocity while keeping pressures at a safer
leve, you would want to go with the slower burning powders.
If you have a short barrel firearm, a faster powder may be better, since you
will not lose nearly as much velocity due to the shorter barrel.
Personally, I like Alliant's Power Pistol for all of my loads. I use it for
9 mm Parabellum, .40, 10 mm, .357 magnum, .38 Special (with JSP's only), and
..45 ACP. It has some muzzle flash, but it's clean burning, and you can
safely propel bullets at some pretty high velocities using it.
fl...@alaska.net
#How do you know when to use a fast burning powder or a slow burning one?
That information is found in reloading manuals....how many have you
looked at? ;^)
Jay T
Bill Barott
and in this a good starting load is a MUST.
BUT there are certain generalizations that can be made.
(1) For light bullets use faster powders. For heavier bullets, use
slower powders.
(2) For short barrels use faster powders. Longer barrels like slower
powders.
(3) For gas-operated weapons, use faster powders. For bolt guns, use
slower powders.
(4) For slower twist rates use faster powders. Fast twist rates like
slower powders.
(5) Cartridges of limited case size like .458 win mag and 8mm mauser
require faster powders as you can't stuff enough of the slow stuff in
the case.
(6) For best accuracy, use a powder that burns in the barrel, with a few
exceptions this means avoid the slowest-burning powders.
B.
"Andy J." wrote:
> ...
Clark Magnuson
1) peak efficiency at 1:14
2) peak horsepower at 1:12
And likewise there are two powder speeds for a cartridge and bullet:
1) peak economy with a faster powder [Bullseye in a 45 acp]
2) peak power with a slower powder [Power Pistol in a 45 acp]
Another way to look at it, is size and shape of the powder chamber and
weight of the bullet drives the optimum powder speed:
1) [Longer] .357 mag and 9mm both shooting 125 gr bullets have one main
difference: the .357 has a longer powder chamber and so peak power is
with H110, a slower powder. Meanwhile, 9mm peak power is with Powder
Pistol, a faster powder.
2) [ Bigger] .308 and 50 BMG have the same shape, but 50 BMG is bigger.
The optimum powder for .308 is in the middle of the powder speed
hierarchy [I use IMR4895], where as 50 BMG uses the slowest powder
~H8700.
3) [Heavier ] The 124 gr 9mm and 147 gr 9mm have different weight
bullets. The 124 gr is optimized with Power Pistol, while the heavier
147 gr is best with the slower powder, 3N37.
4) [Necked down Shape ] The .243 and .308 have the same size and shape
bodies, but the .243 is necked down to a smaller diameter bullet. Both
can both shoot ~100gr bullets. The necked down .243 would be optimized
with the the slower 4350, while the .308 would use a faster powder like
IMR4895.
Pankoski
the powder manufacturer.
"Andy J." wrote:
> ...
JOHN GARAND
#How do you know when to use a fast burning powder or a slow burning one?
#
#Thanks,
#Andy
Check the recommended powders (and range of load weights) in a manual
for the caliber you have in mind?
Andy J.
fl...@alaska.net wrote:
# Someone wrote:
#
# #How do you know when to use a fast burning powder or a slow burning
one?
#
# That information is found in reloading manuals....how many have you
# looked at? ;^)
#
# Jay T
Take a look at other answers to my post. How many different manuals do
you think one would have to read to distill concise, valuable
information like that? Maybe all of them. I have read many and still
felt compelled to ask the question. What about you? How do you choose
between fast and slow powders on a particular load? Also, if you can
be specific about a particularly good chapter on this topic in one of
the manuals, let me know which it is.
Thanks,
Andy
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Ron Seiden
# you think one would have to read to distill concise, valuable
# information like that? Maybe all of them. I have read many and still
# felt compelled to ask the question. What about you? How do you choose
# between fast and slow powders on a particular load? Also, if you can
# be specific about a particularly good chapter on this topic in one of
# the manuals, let me know which it is.
One of the things I did was to get those caliber-specific manuals
(especially Midway's "LoadMAP"). Then I was able to quickly compare
velocity, pressure and (with some math) volume amongst different loads of
various powders. What I looked for was best velocity at lowest pressure that
most nearly filled the case. I also considered whether there was much room
to play between min & max loads for a powder (I prefer to have some "elbow
room" when working up loads). Sometimes the answer isn't very clear and
sometimes it sorta jumps off the page at you.
This is why you're having trouble getting any simple direct answers -- and
why there are so many powders for sale. You gotta consider what caliber
you're looking at, are you going for most accurate or highest velocity or
cleanest burning or . . . Even when I want to experiment with another
powder, I also have to consider what's available locally. No easy answers,
but that's part of the fascination with the hobby.
fl...@alaska.net
#...Take a look at other answers to my post. What about you?
# How do you choose between fast and slow powders on a particular load?....
Gee, no need to become so defensive. Realize that your post gave zero
clues as to your experience level, it didn't even supply a distinction
of handgun, rifle or shotgun powders. Other posters also
misunderstood you post and gave a response similar to mine - does that
make us all guilty of not giving you the answers you wanted? Most
basic questions like yours which are posted in this NG are from those
who have not read the reloading manuals. If my response offended you
( as it appears to have done ) then I appologize.
The problem with some of the answers posted here is that some are not
correct. One example is the suggestion to use faster powders in short
barrels. If one wants the best velocity in a short barrel, this idea
has been proven incorrect many times. For practical purposes the
powder which produces the highest velocity in a long barrel will also
do so in a short barrel - handgun or rifle. There are other
examples. Most responses were correct or made sense, but how do you
know which ones to trust?
Most manuals - the Lyman is one example which is commonly cited in the
NG as a good one; the Nosler Manual also discusses choosing fast or
slower powders as did Hodgdon - either begin to answer the question or
give clues to which powder may be best for a certain use if they give
no verbage answering your specific quesiton. Many times powders are
recommended in the individual cartridge data section, stating that a
certain powder gave better accuracy or higher velocity or low recoil
with good uniformity. Since these are the usual goals for reloaders (
though not always the only ones ) the manuals have pretty well covered
the bases.
Jay T
WVanhou237
writes:
#
#How do you know when to use a fast burning powder or a slow burning one?
#
#
Roughly speaking, heavy bullet/ large case/long barrel = slower powder.
Light bullet/ small case/ shorter barrel = faster powder powder.
For instance, in 6.5x55 of 140/129gr weight I get good accuracy with
IMR4350. But with 85/100gr bullets I go to IMR4320.
Most roading manuals give a range of powders and calibers that go
together.
Bill Van Houten (USA Ret)
"No matter how hard you try, you can't throw a potato chip very far."
"Linus"
Andy J.
# # How do you choose between fast and slow powders on a particular
load?....
#
# Gee, no need to become so defensive. Realize that your post gave zero
# clues as to your experience level, it didn't even supply a distinction
# of handgun, rifle or shotgun powders.
Thanks, Jay. Sorry if I seemed defensive. It wasn't my intention. I
purposely left out the specifics on the caliber, etc. in my original
question because I am only looking for the generalities surrounding the
process (like fast burn for lighter rounds or higher velocity or
whatever). Specifically, I am loading .45ACP and .308 for accuracy and
I've tried the loads in the books; now I'm just trying to predict, in
general, what will happen if I change powder burn rate. I was afraid
if I was too specific with the question that the answers would have
been too specific. Anyway, thanks for taking the time to answer in the
first place. I'll check out the chapters in Nosler (et al) that you
recommend. Sorry that I sounded so abrasive, hard for me to
communicate as clearly in email sometimes. Good shooting, ...Andy
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Carl Vickery
# How do you know when to use a fast burning powder or a slow burning one?
# Thanks,
# Andy
The other posters have offered excellent advice.
I have found the chart below to be useful.
Powders are listed by burn rate (fast at the top, slow at the bottom)
and by density (dense at the right, 'fluffy' at the left).
I have often found that powders close to each other on the chart have
similar characteristics.
If a load manual recommends a specific powder for a particular
application, the chart below can sometimes point one at other suitable
powders.
Hope this helps.
.40 .50 .60 .70 .80 .90 1.00
|----|----|----|----|----|----|----|----|----|----|----|----|----|
Hodg Clays x
Vihta N310 x
Herc Red Dot x
Herc Bullseye x
IMR 700X . . x . . . . . . . . . . . .
Accur AA2 x
Vihta N320 x
Win 231 x
Hodg HP-38 x
Win WST . . . x . . . . . . . . . .
Hodg Intl Clays x
Herc Green Dot x
Vihta N330 x
IMR 7625 x
IMR PB . . . x . . . . . . . . . .
Win WSL x
Hodg Univ Clays x
Herc Unique x
Win WAP x
Accur AA5 . . . . . . . . . .x . . . .
Win WSF x
Vihta N340 x
Win 540 x
Herc Herco x
Hodg HS6 . . . . . . . . . . x . . .
IMR 4756 x
Vihta 3N37 x
IMR 800X x
Vihta N350 x
Hodg HS7 . . . . . . . . . . . x. . .
Herc Blue Dot x
Accur AA7 x
Win 571 x
Herc 2400 x
Vihta N110 . . . . . . . .x . . . . . .
Accur AA9 x
Hodg 110 x
Win 296 x
IMR 4759 x
Vihta N120 . . . . . . . . . x . . . . .
IMR 4227 x
Hodg 4227 x
Vihta N130 x
Accur 1680 x
Vihta N133 . . . . . . . . . . x . . . .
IMR 4198 x
Hodg 4198 x
Hodg 4198SC x
Herc RL7 x
Accur 2015BR . . . . . . . . . . x . . .
IMR 3031 x
Hodg 322 x
Accur 2230 x
Win 748 x
Hodg 335 . . . . . . . . . . . . .x .
Hodg BL-C(2) x
Accur 2460 x
IMR 4895 x
Hodg 4895 x
Herc RL12 . . . . . . . . . . . x . . .
Vihta N135 x
IMR 4064 x
Accur 2520 x
IMR 4320 x
Vihta N140 . . . . . . . . . . x . . .
Accur 2700 x
Herc RL15 x
Hodg 380 x
Win 760 x
Hodg 414 . . . . . . . . . . . x . .
Vihta N150 x
Accur 4350 x
IMR 4350 x
Hodg 4350 x
Hodg 4350SC . . . . . . . . . . . x . . .
Herc RL19 x
Vihta N160 x
IMR 4831 x
Hodg 450 x
Hodg 4831 . . . . . . . . . . . x . . .
Hodg 4831SC x
IMR 7828 x
Accur 3100 x
Vihta N165 x
Herc RL22 . . . . . . . . . . .x . . .
Win WMR x
Hodg 1000 x
Vihta 170 x
Hodg 870 x
Accur 8700 x
|----|----|----|----|----|----|----|----|----|----|----|----|----|
.40 .50 .60 .70 .80 .90 1.00
Carl Vickery
ca...@ti.com
fl...@alaska.net
#...Specifically, I am loading .45ACP and .308 for accuracy and
#I've tried the loads in the books; now I'm just trying to predict, in
#general, what will happen if I change powder burn rate.....
The .45 ACP, like other straight-walled cases, makes powder burning
rates a bit easier to understand. In general terms, a lightweight
bullet like a 185-grain HP can be driven faster than a heavier
230-grainer, which means that the 185 accelerates more quickly to the
muzzle. As it accelerates the bore volume behind it increases more
rapidly too, needing a faster burning powder to keep up with the
expanding space. If the same powder was used with the 230-grain
bullet, the slower increase in bore volume behind the slower bullet
would mean that the fast powder would raise pressures higher because
the 230-grain bullet was not moving out of the way fast enough.
Conversely, the heavier, more slowly accelerating bullet needs a
slower burning powder to keep the expanding bore volume full without
creating excessive pressures.
Looking at .45 ACP load data can muddy things a bit, because sometimes
the same powder gives the highest velocities with both bullets.
That's why generalities can be confusing.
The data below came from a G&A article in September 1987. The
magazine started with a 24" barrel chambered in .308 WCF, and
developed two equal-pressured loads ( 52,000 psi ) with 180-grain
bullets using IMR 4320 and IMR 4198. They cut off the barrel in
increments got the following velocity results:
Powder 24" 20" 16" 12"
4320 2710 2620 2480 2300
4198 2460 2380 2280 2140
Clearly the faster powder never worked "better" in the shorter barrels
for velocity generation; the slow powder was always superior - this
continued when the barrel was only 8" long. But if velocity isn't the
primary concern, a faster powder will create less blast and flash, may
give better accuracy, and will give less recoil. This is because the
fast powder is more fully consumed by the time the bullet exits, and
the bore pressure is lower. The slow powder is still burning and bore
pressure is higher, so noise and flash will be greater too.
Jay T
Paul Mays
that you want a full burn of charge before the projectle leaves the muzzle (
or gas port on gas operated autoloaders) Loading tables for powders will
give the best load for a powder for case/barrel/bullet combo. If you check
them you'll note as caliber gets larger or velocities get lower a slower
burn rate powder is more offten recommended. Then you pick and chose to fit
your need ... as example if I load 444 marlin rounds I'll use a dupont
slower burn so that I get all powder burnt just before the projectle leaves
the muzzle but still burning just before... but load a 25.06 with a 75gn
and you have to burn the powder fast cause that bullet is at the target
before the firing pin hits the primer! So... my rule big and slow burn it
slow...small and fast powder be fast.....
Paul Mays...
(my new gun needs powder grains the size of golf balls...
http://members.tripod.com/~BennyJets/cannon.html )
"Andy J." wrote:
> ...
Ken Marsh
In article <3A614E01...@Mays.com>, Paul Mays <Pa...@Mays.com> wrote:
So... my rule big and slow burn it
#slow...small and fast powder be fast.....
So, how do you reconcile this with the fact that the 444 does best
(velocity-wise) with powders like 4198 or 4895 and the .25-06 with
powders like 4350 and 4831? What happens when you try to achieve
4831-like velocities in the .25-06 with 4198? (Hint, you can't without
massive overpressures).
Large bores drop pressure fast upon debulleting, as the wide bullet
leaves a large swept volume behind as it moves small distances. A 444
effectively doubles chamber volume when the bullet moves about one
cartridge length. In order to keep the pressure high enough to keep the
powder burning at all, you have to have a fast powder to maintain the
pressure.
In a heavily necked-down cartridge, the bullet has to move half way down
the barrel before chamber volume even doubles. In this case, pressures
with a fast powder will go through the roof. You need a powder that will
continue to burn slow under sustained high pressures- a "slow" powder.
Ken.
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Clark Magnuson
Ken Marsh wrote:
# Large bores drop pressure fast upon debulleting, as the wide bullet
# leaves a large swept volume behind as it moves small distances. A 444
# effectively doubles chamber volume when the bullet moves about one
# cartridge length. In order to keep the pressure high enough to keep the
# powder burning at all, you have to have a fast powder to maintain the
# pressure.
#
# In a heavily necked-down cartridge, the bullet has to move half way down
# the barrel before chamber volume even doubles. In this case, pressures
# with a fast powder will go through the roof. You need a powder that will
# continue to burn slow under sustained high pressures- a "slow" powder.
#
To get this and other insights, I had to stare at load tables until I could
find a pattern.
I don't recall reading it anywhere before this post.
Clark