Velocity. burn rate & muzzle flash

[Dieselhorses]

So, I happen to run across a YT video of a fellow trying to explain the results from faster and slower burning powders. I believe he said slower powders didn't produce the velocities that faster powders produced, but didn't deliver muzzle flash? Or is it the other way around? Just wanted to see what everyone's thoughts were. (I'll try to find the link again.)

[243winxb]

Slow powders produce the higher velocity. The unburnt powder exiting the barrel may produce a muzzle flash. The air/fuel mixture needs to be correct.

Some powders have a flash suppressant, makes a difference.

[Hick]

Slow powders produce the higher velocity. The unburnt powder exiting the barrel may produce a muzzle flash. The air/fuel mixture needs to be correct.

Some powders have a flash suppressant, makes a difference.

Yep.. and faster powders generally hit their peak pressure much quicker, before the bullet can move much, which tends to limit how much you can use, which tends to result in lower velocities compared to what you can accomplish with a slow powder.

[M-Tecs]

I am not aware of any of the commonly available smokeless powders that do not have a flash suppressor in them. In the 90's some of the local HighPower shooters were using a Russian or Chinese powder that did not have any flash suppressors. Even during bright daylight, you got a soccer ball size fireball from the 308 match rifles.

Smokeless ammunition generates its own oxygen so the oxygen/fuel mixture can only be controlled by the powder manufacturer.

As to faster or slower powders producing higher velocities that depends. Faster powders may produce higher velocities in 1 7/8" revolvers. In rifles slower powders hold a longer pressure curve and produce greater velocities.

[243winxb]

Flash suppressants interrupt free-radical chain reaction in muzzle gases and work against secondary flash. They are typically alkali or alkaline earth salts that either are contained in the formulation of the propellant or exist as separate granules.

Spherical Powders & ball powers have some listed, along with many other chemicals.

Potassium carbonate reduced flash as well as potassium nitrate and better than
potassium sulfate. In addition, the anmonium salts do not contribute to the
smoke.

[243winxb]

Flash suppressants interrupt free-radical chain reaction in muzzle gases and work against secondary flash. They are typically alkali or alkaline earth salts that either are contained in the formulation of the propellant or exist as separate granules.

Spherical Powders & ball powers have some listed, along with many other chemicals.

Potassium carbonate reduced flash as well as potassium nitrate and better than
potassium sulfate. In addition, the anmonium salts do not contribute to the
smoke.

https://archives.fbi.gov/archives/about-us/lab/forensic-science-communications/fsc/april2002/mccord.htm#disablemobile

[Dieselhorses]

Flash suppressants interrupt free-radical chain reaction in muzzle gases and work against secondary flash. They are typically alkali or alkaline earth salts that either are contained in the formulation of the propellant or exist as separate granules.

Spherical Powders & ball powers have some listed, along with many other chemicals.

Potassium carbonate reduced flash as well as potassium nitrate and better than
potassium sulfate. In addition, the anmonium salts do not contribute to the
smoke.

https://archives.fbi.gov/archives/about-us/lab/forensic-science-communications/fsc/april2002/mccord.htm#disablemobile

So "slow powders"=higher velocity with a chance of muzzle flash? And "fast powders"=lower velocity with no flash? I somewhat understand the concept of the slower powders as I load for a .500 magnum and "crimp" is very important.

243winxb, you sound like you have a degree in chemistry...?

[243winxb]

No degree, just Google. Hodgdon & other companies have Safety Data Sheets (SDS) that show what is in powders.

In handguns, a chronograph may show what burn rate of powder produces the best velocity? Revolvers vent from the cylinder gap, loosing pressure.

The information on the Hodgdon website only addresses barrel length, not burn rate. They do point out that some newer powders will produce more velocity, with less grains of powder used, then older types of powder.

Using less powder reduces the cost of reloading.

Sold my chronograph back in the late 70s, after checking all my loads. Velocities were close to book data.

[MostlyLeverGuns]

Slower powders produces more velocity UNTIL you run out of room in the cartridge case. Powder burn rate is best based on case capacity - 30-30 is better with 3031 or 4895, can't get enough 4350 or 4831 to reach max velocity and pressure; 308 runs better with Varget , 4064, Reloder 15, runs out of room with 4831 and H1000; 300 Win Mag likes H1000, 4831, Reloder 22 but can't get enough 5010 to reach 'Max' velocity so the answer is 'IT DEPENDS' how you define fast and slow powder and the case capacity. Oh yeah, powder burn rates do vary by case shape, capacity, and pressure to add to the difficulties, muzzle blast and flash depends on barrel length and flash reducing compounds in the powder too.

[1hole]

There is always a desire to have things operate in a fixed pattern but in reloading no such predictions can be made, there are too many things interacting for that to be possible. Muzzle flash/blast mostly depends on the powder quantity AND the type AND the burn rate AND the chamber pressure when the bullets exit.

Gun powder burn rate is not linear, powder burns faster as the pressure goes up. So, given published powder burn rates can and do cross in different cartridges AND with different bullet weights, depending on the actual peak pressure.

A given quantity of a fast powder driving a certain bullet weight can easily reach max safe pressure within 2-3 inches of bullet travel; change any component and no one knows what the new pressure may be nor where it will peak.

"Slow" powders are only slow in comparison, they are still quite fast. The safe pressures for slow powders in common large bore magnum rifle cartridges driving heavy-for-caliber bullets will commonly peak at about 5-7 inches of bullet travel.

There is little chamber pressure lost from the cylinder gap of a revolver. The burning pressure directly increases the density of the gasses. At 30K psi those gases are about 2,000 times more dense than atmospheric and it's all chasing the bullet straight down the bore; that's a lot of high speed and a great density change! Very little of those heavy, hard charging hot gases can immediately turn 90* at a cylinder corner and exit the small gap.

[john.k]

In fact ,faster powders always produce higher muzzle velocity.....provided your gun system can handle the pressure.........the extreme with available powders is thought to be approx 135,000 psi peak pressure.

[M-Tecs]

In fact ,faster powders always produce higher muzzle velocity.....provided your gun system can handle the pressure.........the extreme with available powders is thought to be approx 135,000 psi peak pressure.

I disagree. The longer peak pressure is maintained the higher the velocity will be if the peak pressures are the same. Longer peak pressures favor slower powders unless the barrel is really short.

[243winxb]

In fact ,faster powders always produce higher muzzle velocity.....provided your gun system can handle the pressure.........the extreme with available powders is thought to be approx 135,000 psi peak pressure.

Here is what 135,000 PSI will get you. https://www.thehighroad.org/index.php?media/albums/kaboom.24/

If running proof loads all the time, your sure to find the weak spot. KABOOM

[uscra112]

This subject is far too complex for a forum post. Suffice to say that I'd rate that YT video as "junk'.