Powder burn rates

[crabo]

How do you determine when to try a faster or slower powder when working up a load?

Is it different for rifles, pistols and revolvers?

Do light or heavy weights for caliber make a difference?

Thanks,

[c3d4b2]

A rule of thumb is heaver bullets and bullets with longer bearing surfaces tend to do better with slower powders.

From my limited understanding.

The heaver bullets have more inertia and are harder to get moving which causes the pressure to peak before the bullet moves down the barrel to increase the volume of the gas chamber.

The longer bullets require more force to push them into the rifling which causes the pressure to peak before the bullet moves down the barrel to increase the volume of the gas chamber.

[MtGun44]

Some of it is pure economics. I can load Unique in my .45 ACP and use maybe 5 or 6 grains
of powder, if I use WW231 I would use 5.7 gr. But I choose Titegroup or Bullseye because I
get the same velocity with only 4.7 gr of powder. So, I get more loads per pound, saving
money.

Bill

[stubshaft]

I agree with both of the previous reaons/opinions and offer another reason to the mix.

Barrel length.

I have three different barrels for a 500 S&W to be mounted on an Encore frame. They range from 12 1/2" to 24" in length. Loads that perform well in the 24 incher will leave alot of unburned powder in the 12 1/2" barrel. For that particulaer barrel and even the 15 incher I would have to go to a faster powder.

[missionary5155]

Good morning
In my simple form of thinking Pressure to the base of the bullet is the key. All the mentioned facts above are part of the soup that ends up putting pressure to the base of my Boolit. If it is bare and 40-1 mix I want as little as possible Pressure on the boolit base but enough to get it moving to my desired FPS within the confines of the barrel that particular firearm has. A harder mix like WW will comfortably withstand more pressure before ugly things happen to it´s base to discourage accuracy.
There is a chart that gives the approximate pressure lead mixes can support. You can do a SEARCH and find that. Exceep that pressure for a given mix EXCESSIVELY and you will see evidence of deformation.
Boolit recovery from a reasonably soft material will generaly let you see your fired boolits base. Dirt works just fine. That Fired Boolit base will help you understand what your load is doing to that boolit base before it leaves the barrel.
It comes down to why I do not release Nitrous Oxide into the cylinders of my 1971 BMW 750 motorcycle. I just do not know if those piston tops will safely standup to that kind of pressure. Wack anything with enough pressure and something has to break and in our case the boolit base is the weakest link.

[lwknight]

If you have a short barrel, you will do best with a faster powder. Longer barrels cn do fine with slower powder. Short barrel loads can never outperform long barrel loads in a long barrel. Slower powders are generally more forgiving but will gives slow velocities in short barrels.

Same with bullet weights. light bullets usually do poorly with slow powder and fast powder cannot get the full potential from heavier bullets and especially so in long barrels.

[JohnH]

I have a 28" 243 Winchester Pro Hunter barrel for my Encore. I bought this barrel for Pdoggin. The two loads I use are (1) 42 grains of 4895 under a Nosler 55 grain BT. Load makes right at 3570 fps. Fast, accurate and deadly. (2) 52 grains of surplus 860 and the Nosler 70 grain BT. Load makes 2700 fps. Slow, accurate and deadly. Both loads hold up well to 400 yards which is about the mechanical limits of the rifles pdog accuracy

In making up a load for deer last year for this barrel, I used H450 (don't recall the charge), an old Hodgdon power H205 (think WW760 speed) at 42 grains and 34 grains 3031 all under the Remington 100 grain Corelokt. Surprisingly the 3031 load shot best at 200 yards though at 100 one could tell no difference between the groups.

I like what Mike Venturino once wrote "You can spend a life time and never find the best load for a rifle". The conventional wisdom is "light bullets fast powders; heavy bullets slow powders". But in the end, one has to shoot them so the gun can tell you what it likes best.

[MtGun44]

The idea that slow powders give slow velocities in short barrels is wrong for the magnum
pistols, as logical as it seems. You will find that W296/H110 (slow magnum powder) will
give higher velocities in .357/41/44 mag in SHORT barrels than the faster powders like
Unique (medium speed) or real fast like Bullseye, or Titegroup. Of course, the slow mag
powders give the fastest velocities in the long barrels, too.

I have not studied it for rifles, so don't know.

If you want the absolute fastest speeds, the slower magnum powders beat them all
in even short barrels in the magnum pistols. I know this because it surprised me when
I discovered it.

Bill