OS OK
01-24-2016, 05:06 PM
This following 'interpretation' is from an article published in "SPEER, Manual #7 for Reloading Ammunition", pub. 1966-7. author; DR. Edgar L. Eichhorn
I had to read it several times endeavoring to understand exactly what happens in this 'Internal Ballistics' subject as it was different than I'd imagined. Another problem for me was this event all took place in 1.35 milliseconds, .00135 second, 135/100,000's second. PDQ< 'pretty damn quick'. When I drew a pair of lines horizontally across the paper and imagined those lines representing my rifle barrel and filled in the information presented and realized that those lines also represented a 'time line'…facts started to sort themselves out and these numbers started to make perfect sense.
I have followed the threads regarding 'Powder burn Rates' and found them very informative. The posts make it clear to me that some of us, try as we might, do not have a true or factual understanding of this sequence of events. Our choices in Powders in many instances are unfounded and misunderstood. On the other end…some here have a very in depth understanding and their explanations parallel findings found in 'white papers' published in 'Academias' circles where Physicist and the like baffle each other with the latest minutia in their fields. The 'bottom line' regarding all this is…Us 'Blue Collar' types don't usually have a clue as to what these people are talking about. On the other hand, we do understand clearly presented facts.
Please take the time to round up a pencil/paper and do a quick sketch for yourself as I did…I promise, you won't soon throw it away.
The 'Pyrostatic Epoch' begins with 'primer ignition'
elapsed time (et.) 5/100,000's second
the boolit is just this instant going to 'START' to move, but it has not
6,000 lbs./sq.in. pressure develops, the brass swells in chamber and seals it
4,000* F. temperature/in chamber
3 1/2% of powder charge is consumed
The tip of the boolit has traveled 1 inch, is now fully in lands/grooves and engraved, acceleration has begun
et. 40/100,000's second
70,000 lbs./sq.in. and pressure is now at maximum
3,470* F. temperature is maximum
38% of powder charge is consumed
1,000 FPS Velocity and climbing
681.8 MPH and heading toward the sound barrior [ V x FPS x .6818 = MPH ] {this my extrapolation, hope it is correct.)
The boolit has traveled 9 inches and the 'Propulsive Epoch' has ended
et. 75/100,000's second
24,000 lbs./sq. in. pressure and is in 'decline' as the accelerating boolit is making more volume behind it than the 'hi-pressure gasses' are able to fill.
2,300* F. also in decline
100% of charge is consumed
2,200 FPS Velocity and climbing as it is under 'Hot expanded gas propulsion' only, from here on out
1,499 MPH has broken the sound barrier and continues to climb
The boolit is exiting the 27 in. barrel
et. 135/100,000's second…1.35 millisecond… .00135s
6,000 lbs./sq. in. remaining pressure flashes into atmosphere and is luminous to the eye…this is where some of us remember to put in our 'earplugs'.
1,490* F. gasses and powder and lube smoke fill the air, eyes pop and everyone grins real wide. The virginity of a fresh 'bullseye' is currently at risk!
2,700 FPS Velocity and this now is in decline
1,840 MPH and if it travels downrange aprox. 900 yards it will again cross back through the sound barrier where its RPM will be a critical factor in flight.
162,000 RPM as it emerges from this 1:12 twist barrel [ ((12/T) x V)60)=RPM ]…short version > [ (V x 720)/T = RPM ]…T=twist, V=velocity
The author never stated what this cartridge was nor the powder but probably a proof round at this pressure and a .30/06 or .308, not that it matters really but it just puzzled me as it did some of you. Could be of several different calibers as we don't know the projectile weight or diameter...although…
none of that matters as we can see that these 'facts' do apply to a 'rifle' and it has been the speculation of us all as to whether or not a certain powder will do this or that. Given a more clear picture of 'internal ballistics' in this 'general description' I think we can all take a moment and do some 'Mulling' because more than one of us here are now 're-figuring' our assessments of the things that 'go bang' in the chamber.
The author mentioned that the 9 inch point in the barrel will vary from shot to shot and of course vary with a faster/slower 'rifle' powder but not change 'appreciabily'. The following calibers/powders reach their respective max./pressure at the following times. Only the graphs were published and did not state at what point the projectile was in the barrel. (Varying case volumes/bore dia.'s would account for much of this discrepancy in time.)
.222 Rem. Mag., IMR 4198…max.@ 32/100,000's sec.
.22-250……………..IMR 4320…………….58/100,000's sec.
.243 Win…………...IMR 4350…………...66/100,000's sec.
7mm Rem. Mag...IMR 4831…………...64/100,000's sec.
.300 Win. Mag…...IMR 4350…………...62/100,000's sec.
These all so close together represent to me that 'in general' that the boolit will be aprox. 9 inches down barrel when we speak of 'powder burn rates' and I can't see it varying by wild amounts until we start comparing pistol powders.
I have searched the net and never found any articles that give this same run-down for pistol powder…if any of you here should ever find one…or anything close please post here and advise us all as I find this to be one of the 'most informative' articles I have ever read.
Thanks for your patience…hope this clears some misguided reasoning out there…Also…I think this extremely hi-pressure round is a 'Proof Round'.
I had to read it several times endeavoring to understand exactly what happens in this 'Internal Ballistics' subject as it was different than I'd imagined. Another problem for me was this event all took place in 1.35 milliseconds, .00135 second, 135/100,000's second. PDQ< 'pretty damn quick'. When I drew a pair of lines horizontally across the paper and imagined those lines representing my rifle barrel and filled in the information presented and realized that those lines also represented a 'time line'…facts started to sort themselves out and these numbers started to make perfect sense.
I have followed the threads regarding 'Powder burn Rates' and found them very informative. The posts make it clear to me that some of us, try as we might, do not have a true or factual understanding of this sequence of events. Our choices in Powders in many instances are unfounded and misunderstood. On the other end…some here have a very in depth understanding and their explanations parallel findings found in 'white papers' published in 'Academias' circles where Physicist and the like baffle each other with the latest minutia in their fields. The 'bottom line' regarding all this is…Us 'Blue Collar' types don't usually have a clue as to what these people are talking about. On the other hand, we do understand clearly presented facts.
Please take the time to round up a pencil/paper and do a quick sketch for yourself as I did…I promise, you won't soon throw it away.
The 'Pyrostatic Epoch' begins with 'primer ignition'
elapsed time (et.) 5/100,000's second
the boolit is just this instant going to 'START' to move, but it has not
6,000 lbs./sq.in. pressure develops, the brass swells in chamber and seals it
4,000* F. temperature/in chamber
3 1/2% of powder charge is consumed
The tip of the boolit has traveled 1 inch, is now fully in lands/grooves and engraved, acceleration has begun
et. 40/100,000's second
70,000 lbs./sq.in. and pressure is now at maximum
3,470* F. temperature is maximum
38% of powder charge is consumed
1,000 FPS Velocity and climbing
681.8 MPH and heading toward the sound barrior [ V x FPS x .6818 = MPH ] {this my extrapolation, hope it is correct.)
The boolit has traveled 9 inches and the 'Propulsive Epoch' has ended
et. 75/100,000's second
24,000 lbs./sq. in. pressure and is in 'decline' as the accelerating boolit is making more volume behind it than the 'hi-pressure gasses' are able to fill.
2,300* F. also in decline
100% of charge is consumed
2,200 FPS Velocity and climbing as it is under 'Hot expanded gas propulsion' only, from here on out
1,499 MPH has broken the sound barrier and continues to climb
The boolit is exiting the 27 in. barrel
et. 135/100,000's second…1.35 millisecond… .00135s
6,000 lbs./sq. in. remaining pressure flashes into atmosphere and is luminous to the eye…this is where some of us remember to put in our 'earplugs'.
1,490* F. gasses and powder and lube smoke fill the air, eyes pop and everyone grins real wide. The virginity of a fresh 'bullseye' is currently at risk!
2,700 FPS Velocity and this now is in decline
1,840 MPH and if it travels downrange aprox. 900 yards it will again cross back through the sound barrier where its RPM will be a critical factor in flight.
162,000 RPM as it emerges from this 1:12 twist barrel [ ((12/T) x V)60)=RPM ]…short version > [ (V x 720)/T = RPM ]…T=twist, V=velocity
The author never stated what this cartridge was nor the powder but probably a proof round at this pressure and a .30/06 or .308, not that it matters really but it just puzzled me as it did some of you. Could be of several different calibers as we don't know the projectile weight or diameter...although…
none of that matters as we can see that these 'facts' do apply to a 'rifle' and it has been the speculation of us all as to whether or not a certain powder will do this or that. Given a more clear picture of 'internal ballistics' in this 'general description' I think we can all take a moment and do some 'Mulling' because more than one of us here are now 're-figuring' our assessments of the things that 'go bang' in the chamber.
The author mentioned that the 9 inch point in the barrel will vary from shot to shot and of course vary with a faster/slower 'rifle' powder but not change 'appreciabily'. The following calibers/powders reach their respective max./pressure at the following times. Only the graphs were published and did not state at what point the projectile was in the barrel. (Varying case volumes/bore dia.'s would account for much of this discrepancy in time.)
.222 Rem. Mag., IMR 4198…max.@ 32/100,000's sec.
.22-250……………..IMR 4320…………….58/100,000's sec.
.243 Win…………...IMR 4350…………...66/100,000's sec.
7mm Rem. Mag...IMR 4831…………...64/100,000's sec.
.300 Win. Mag…...IMR 4350…………...62/100,000's sec.
These all so close together represent to me that 'in general' that the boolit will be aprox. 9 inches down barrel when we speak of 'powder burn rates' and I can't see it varying by wild amounts until we start comparing pistol powders.
I have searched the net and never found any articles that give this same run-down for pistol powder…if any of you here should ever find one…or anything close please post here and advise us all as I find this to be one of the 'most informative' articles I have ever read.
Thanks for your patience…hope this clears some misguided reasoning out there…Also…I think this extremely hi-pressure round is a 'Proof Round'.