Powder burning rate >< muzzle flash

[chriske]

Am I right in assuming that :
All else being equal (gun, caliber, primer, bullet,) a charge of slow-burning powder can achieve the same muzzle velocity as a load of fast-burning powder, but will do this at lower pressure ?

Does this also mean that the slow-burning powder charge will exhibit more muzzle flash ?

[pmeisel]

No, it's a little more complicated than that. For any given cartridge and barrel length, there will be a range of powders that will work effectively, then there will be some that are too fast or too slow to work well, usually.

Big bottlenecked cartridges and long barrels will tend to slower powders, straight necks and shorter barrels to lighter powders.

Heavier loads in a given cartridge are usually a little slower, relatively faster powders are usually better for lighter loads... but this is a generalization and should not be relied on for experimentation. The powder and bullet companies have paid people to experiment for us and publish the results, so use that information.

Slower powders, all else equal, will have more flash, more powder burning outside the barrel.

Slower powders will reach peak pressure later than faster powders, but that may or may not result in the same, or more, or less velocity depending on all the other factors involved.

If you are interested in researching this as a sort of semi-scientific investigation, get a big reloading manual and look at the data for the different powders in different calendars... chart powders across calibers and calibers across powders......

[Art Eatman]

Slower burning powders need a longer barrel to have near-complete combustion and have the maximum area under the curve of pressure vs. time. Regardless, there is no actual "complete" combustion with either fast-burn or slow-burn powders.

The amount of muzzle flash, by and large, is more dependent on barrel length than other factors. That said, some of today's powders have less flash than older compositions with the same burn rate--a function of the chemistry, not the burn rate.

[Go Kiwi]

As an interesting example - My 19 inch barrel .243 loaded with Varget works very nicely and has good velocity. Loaded with slower powder H414 which is supposed to be a "good" powder for .243 it blows the screens off the chrony every shot at 10 feet and makes a flash the size of a small car

You need "enough" barrel length to burn all the powder you are using if that makes sense. The cartridge and bore diameter also affects how much of the burning powder is trapped behind your projectile or wasted as a large muzzle flash

This isnt my picture but its a mean muzzle flash

[LHB1]

In my experience, faster burning powders are used for lower/midrange loads while slow burning powders are ALWAYS used for higher/full power loads. At max load levels, the sudden increase in pressure peaks for fast burning powders make them unsuitable and even dangerous for high velocity loads for a given cartridge in my opinion.

[DBotkin]

That pic looks like when I tried some 2400 loads in my 4" Model 29. Got an orange ball about the size of a basketball, and the concussion had the people in the adjacent lanes at our indoor range leaving in a hurry. My ears hurt, and I was wearing ear muffs.

2400 in a 4" .357 Mag worked fine. 2400 in a 4" .44 Mag, on the other hand...

[HiBC]

In very general terms,I believe you are thinking on the right track.

In very general terms,there will be a range of powders for a cartridge bullet combination.What is best for a 24" bbl,may not be best for an 18" or a 14" handgun bbl. The spectrum of powders gives you choices to tune to your application.

From older powders,I could load (for a bolt gun) very good loads with 4895 or 4350 for a 150 or 165 gr bullet.I would expect more flash from 4350.

I think the software my brother has is "Loads From a Disk"

He can use case volume in gr of water,caliber,bbl length,etc along with load data to estimate burn percentage.It seems like a useful software for estimation.

[Unclenick]

Yes, your thinking in the original post is on the right track in principle, but isn't something I would suggest doing in practice. While it is perfectly true a slower powder can match the velocity of a faster one but with lower peak pressure, it is also the case that because the slower powder does not burn as easily as the faster one, it needs higher pressure to burn well and work efficiently. It is quite a waste to run slow powders at lower pressure as the unburned percentage goes up dramatically and the fouling increases and the consistency of muzzle velocity generally goes down.

When someone suggests a powder is too slow for a given chambering and bullet combination, it generally means that even stuffing the case with all the powder you can squeeze in results in both low pressure and inadequate velocity.