Speed question

[alinwa]

Actually, no, your example does not logically follow. Neither does your primary example, though in a crude form it is basically correct. A consistent load of a consistent powder will give consistent results - even if a component of those results is that some of the powder is still combusting at the time of exit. A given caliber, using molly coated bullets, will require a larger amount of powder to achieve the same muzzle velocity - because the powder reacts more efficiently and/or completely while at the higher pressure. the bore friction keeps that burn efficiency high - the higher the resistance to expansion, the more complete the burn. Which is all well and good if your goal is to burn powder completely. Ours usually isn't - our goal is consistent muzzle velocity (behind an ever increasingly departing bullet - which tends to drop pressure rapidly even before the bullet is gone) - so we throw more of a slower burning powder behind it to keep that pressure high longer. The result is the desired muzzle velocity, at the expense of a complete burn. The side effect is large muzzle flashes from unexpanded gasses and incompletely burned powder being expelled from the muzzle. And so long as our bullets go to where they are pointed, and do it consistently - the unburned, or late burned powder consumed after the bullet is gone is of no real consequence to most shooters.

I don't buy it.

al

BTW, today my loads ranged from 94 grains to 104 grains of powder from a 28" barrel. My ES averaged 11fps over 40rds with some loads at 5fps total spread in group.

On smaller rounds up to 308 case, I CAN SEE THE EFFECT OF INDIVIDUAL KERNELS OF POWDER. Can't convince me that it doesn't follow.

 

[Vibe]

I don't buy it.

al

BTW, today my loads ranged from 94 grains to 104 grains of powder from a 28" barrel. My ES averaged 11fps over 40rds with some loads at 5fps total spread in group.

On smaller rounds up to 308 case, I CAN SEE THE EFFECT OF INDIVIDUAL KERNELS OF POWDER. Can't convince me that it doesn't follow.

There are lots of natural facts of nature that you refuse to be convinced about. I'm not really surprised that this is one of them as well. LOL
Your example follows perfectly, the more individual kernels you have in the process of generating expansion gas, the more gas you have to push the bullet, and the more the bullet will accelerate. But the conclusion that all of these kernels are completely finished producing gas before the bullet exits is a rather large (and erroneous) jump of speculation.

 

[alinwa]

There are lots of natural facts of nature that you refuse to be convinced about. I'm not really surprised that this is one of them as well. LOL
Your example follows perfectly, the more individual kernels you have in the process of generating expansion gas, the more gas you have to push the bullet, and the more the bullet will accelerate. But the conclusion that all of these kernels are completely finished producing gas before the bullet exits is a rather large (and erroneous) jump of speculation.

So what you seem to be saying is...... "as long as you use good ingredients it's not necessary that a reaction complete itself to achieve consistent results?"



al

 

[Roger T]

Some thoughts, As long as the pressure/combustion profile are consistant while the bullet is in the barrel, does it matter what is left unburned (idealy none but does it matter)? Has anyone ever put a white peice of corrogated in front of their Crono to use as a blast shield (check out the unburned powder @ 20' or so.)

 

[alinwa]

In my reality achieving under 10fps ES empirically "proves" a whole bunch of things....

-It proves that leakage around the case is negligible.
-It proves that primers are pretty freakin' consistent.
-It proves that gas blowby is a highly overrated problem
-And it soundly proves that not only is total involvement of the powder charge pretty much a given, that the reaction is completed to within hundredths of a percent.



Extreme Spread of 10 feet per second over 3000 feet per second gives me .33% variation, (I'm severely math challenged BUT) a severiously small deviation from a norm in my (real) world.......This is easily achievable with ZERO attention given to neck tension, unturned factory necks and at any seating depth you care to name.

As little as three yrs ago I'd have scoffed at this number, calling it "impossible." Not even pre-charged air rifles are this consistent and getting this low with a burning powder charge was inconcievable IMO.

Opinions change.

vibe showed me once how turning escaping gas backwards in a muzzle brake is more effective than catching it..... he SHOWED me, convinced me. (the other "natural facts of nature" which I deny don't come to mind, maybe vibe will provide a list?)

Maybe vibe will convince me once again, show me how one can light 50 fires, snuff them all simultaneously and measure equal yields..... I dunno...... but until then





I ain't buying it







al

 

[Vibe]

Not even pre-charged air rifles are this consistent and getting this low with a burning powder charge was inconceivable IMO.

Does one of those air rifles expand ALL of the pressure charge BEFORE the bullet leaves the barrel? Or is there residual pressure behind it even after it leaves (muzzle "blast"). Why would you think your powder has totally quit producing gas by the time it exits? As the burn reaction tapers off (rapidly, but it does) the gas production would become more inconsistent - and you would get larger ES values.

Opinions change.

vibe showed me once how turning escaping gas backwards in a muzzle brake is more effective than catching it..... he SHOWED me, convinced me. (the other "natural facts of nature" which I deny don't come to mind, maybe vibe will provide a list?)

Maybe vibe will convince me once again, show me how one can light 50 fires, snuff them all simultaneously and measure equal yields..... I dunno...... but until then

I ain't buying it


al

I appreciate the complement, and that was a doosie of a thread. As for the other issues....Horsepower comes to mind. LOL.

David

 

[roninflag]

you should try 35.5 of benchmark and a 50 balistic tip in both rifles. i think you will like it.

 

[alinwa]

Does one of those air rifles expand ALL of the pressure charge BEFORE the bullet leaves the barrel? Or is there residual pressure behind it even after it leaves (muzzle "blast"). Why would you think your powder has totally quit producing gas by the time it exits? As the burn reaction tapers off (rapidly, but it does) the gas production would become more inconsistent - and you would get larger ES values.




I appreciate the complement, and that was a doosie of a thread. As for the other issues....Horsepower comes to mind. LOL.

David

I think you mean 'expend???"

But anyways, you've made my point for those who understand this...... the only real difference between the air rifle and the powder rifle is that the pressure for the air rifle, the "reaction," was produced in another room.

You'd lose on the horsepower one....... my answer was the first one in the thread (before it went sideways) and it was quite simply that horsepower is a rate, defined as force over time and the time was so short that very little work is actually being done. Not even "one horsepower" (about 745 watts or 33,000 ftlb/minute.) is actually produced. I was only pointing this out, it's not in disagreement with the fact that the horsepower rating comes out to 45,000hp or whatever it was.....

you could look it up

Or you could rave on A'gain about me being wrong....A'gain mixing ye apples with ye ouranges

Or I could just say "yes, you're right vibe." and "If the action went on a little longer you would actually do enough work to exceed the amount defined as one horsepower."

"We" don't even disagree on this one, only you do

semantics



al

 

[Vibe]

I think you mean 'expend???"

But anyways, you've made my point for those who understand this...... the only real difference between the air rifle and the powder rifle is that the pressure for the air rifle, the "reaction," was produced in another room.

You'd lose on the horsepower one....... my answer was the first one in the thread (before it went sideways) and it was quite simply that horsepower is a rate, defined as force over time and the time was so short that very little work is actually being done. Not even "one horsepower" (about 745 watts or 33,000 ftlb/minute.) is actually produced. I was only pointing this out, it's not in disagreement with the fact that the horsepower rating comes out to 45,000hp or whatever it was.....

you could look it up

Or you could rave on A'gain about me being wrong....A'gain mixing ye apples with ye ouranges

Or I could just say "yes, you're right vibe." and "If the action went on a little longer you would actually do enough work to exceed the amount defined as one horsepower."

"We" don't even disagree on this one, only you do

semantics



al

LOL. In the case of the air rifle, expand more or less equates to expend. But the powder rifle is still producing gas after the bullet leaves - just as that reaction is winding down and is no longer producing it at an acceptable rate, it's not finished, it's just no longer usable.
As for the HP thing...just pulling your chain. LOL. Just as you were mine in response.


But power (and horsepower) is the change in ENERGY with respect to time - not force. Just to be picky.

 

[Rflshootr]

Jaybic,
If you have access to some IMR3031, give it a try. It will probably yeild more velocity then any of the other powders you mentioned using with a 50 grain bullet. I shoot it out of my 700VLS
(26" barrel) with a 55 grain nosler and am right at 3700fps. You shouldn't have a problem getting that with a 50 grainer & a 22".

 

[alinwa]

But power (and horsepower) is the change in ENERGY with respect to time - not force. Just to be picky.

Well, no..... again you're mixing the point.

What you're describing is an acceleration. "Change in energy with respect to time" is an acceleration not a steady state. The average or mean force maintained over time can be expressed as hp. You're probably figuring that because automotive descriptions and other lay terminology use 'force' only in describing torque it's not relevant to hp derivation?

Horsepower was originally arrived at be driving a horse in a circle. It was asserted that the horse could push with 180lb of force. It walked circles for a minute. It didn't "change" nor "have a change in energy" as it walked, it just walked and dude measured.


etc



etc



al

 

[Vibe]

Well, no..... again you're mixing the point.

What you're describing is an acceleration. "Change in energy with respect to time" is an acceleration not a steady state. The average or mean force maintained over time can be expressed as hp. You're probably figuring that because automotive descriptions and other lay terminology use 'force' only in describing torque it's not relevant to hp derivation?

Horsepower was originally arrived at be driving a horse in a circle. It was asserted that the horse could push with 180lb of force. It walked circles for a minute. It didn't "change" nor "have a change in energy" as it walked, it just walked and dude measured.


etc



etc



al

Wrong...on almost every count

http://physics.about.com/od/glossary/g/power.htm
http://en.wikipedia.org/wiki/Power_(physics)