Amount of Propellent Burnt

[59FLH]

When selecting a powder from a choice of multiple powders how much of a factor is 100% burnt by the time the bullet exits the barrel?

If it is a factor, at what point along the barrels length is desirable?

I realize there exceptions to every rule and who gives a darn if the load is accurate and it kills, but for those of you who have an understanding of this phenomenon in ballistics is there a rule of thumb, theory, or fact?

 

[FEENIX]

When selecting a powder from a choice of multiple powders how much of a factor is 100% burnt by the time the bullet exits the barrel?

If it is a factor, at what point along the barrels length is desirable?

I realize there exceptions to every rule and who gives a darn if the load is accurate and it kills, but for those of you who have an understanding of this phenomenon in ballistics is there a rule of thumb, theory, or fact?

Excellent post, and I am glad you did. There have been many posts ridiculing short-barreled rifles and supposedly unburnt powder. LOL! Wait for it ...

@Ernie

 

[Seabeeken]

My 20" ruger 338 rcm burn all off it and hits just shy of 3000 fps. Shoots under .5

 

[Dmagna]

I guess it depends on how overbore the cartridge is, people seem to be going shorter these days to accommodate a suppressor. I cannot have one where I live so I stick with 26 inch barrels on my magnums.

 

[59FLH]

My 20" ruger 338 rcm burn all off it and hits just shy of 3000 fps. Shoots under .5

That's great, how does the 100% burn affect velocity and accuracy? Care to share the science?

 

[59FLH]

I guess it depends on how overbore the cartridge is, people seem to be going shorter these days to accommodate a suppressor. I cannot have one where I live so I stick with 26 inch barrels on my magnums.

Interesting, you're saying the politics of the 2A are a driving force in the phenomenon of powder burn? I there a published study to reference?

 

[Mike D Texas]

I have nothing to back it up but I strive for 100% burn within the barrel, especially since I shoot suppressors. I burned powder is abrasive and contributes to additional heat down the barrel
and into the suppressor.

Also I have to believe that there is possibly additional disruption to bullet flight with more heat and flame out the end of the barrel.

 

[59FLH]

I have nothing to back it up but I strive for 100% burn within the barrel, especially since I shoot suppressors. I burned powder is abrasive and contributes to additional heat down the barrel
and into the suppressor.

Also I have to believe that there is possibly additional disruption to bullet flight with more heat and flame out the end of the barrel.

Mike, do you use QL or GRT or the like to determine at what point in the bullets travel down the barrel you hit 100%. Right at muzzle? 1/2 way, 24" in a 26" barrel?

 

[Dmagna]

Interesting, you're saying the politics of the 2A are a driving force in the phenomenon of powder burn? I there a published study to reference?

What?

 

[Petey308]

I've done a lot of load development with QuickLoad now and while I have looked at that, I haven't really found it to be a factor yet that makes a huge difference overall.

Obviously a faster burning powder will end up burning more in a shorter barrel than a slower burning powder with a given bullet and cartridge combo, but I've still seen MV increase even when 100% of the powder is not burned and you increase the charge. I've also seen MV increase when 100% of the powder is burned and you increase barrel length. As in its 100% burned in a 20" barrel, but if you switch to a 26" barrel your MV will still increase with the same powder and charge weight.

So I personally have stopped paying attention to that figure and only focus on MV and barrel time. I just use a good powder that gives me the desired speed I'm after and at the highest OBT node within safe pressures for any given barrel length.

 

[Mikecr]

I run what-ifs with QL for:
Fastest powder that fills the loaded case at SAAMI max pressure with lowest muzzle pressure for barrel length.

My muzzle pressure goal is ~8Kpsi or less, an attribute I noticed of successful underbore cartridges.
I believe this goal provides for efficient powder burn, clean muzzle release of bullets, and eliminates secondary pressure spiking.
I'm not a suppressor shooter, but I can picture this as something to mind there as well (esp. for semi-autos).

Added; no matter the barrel length, if you keep adding powder, pressure and velocity will go up. But, so will muzzle pressure.

 

[59FLH]

What?

People have suppressors, you can't because of ordinance, that seems like politics. You mention the popularly of over bore cartridges and short barrels.

How does that explain 100% powder burn and it's effects?

 

[Mike D Texas]

Mike, do you use QL or GRT or the like to determine at what point in the bullets travel down the barrel you hit 100%. Right at muzzle? 1/2 way, 24" in a 26" barrel?

I use QL. I would say I like to see it burned by 80% of barrel length, but really as long as it calculates full burn within the barrel I'm ok.

 

[59FLH]

Peter308, if necessary let's start another thread, but you may have touched on what I am after in % powder burn effects on barrel time.