doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Pressure and Velocity

Drew, That's a great paper on the subject.

et al, note that his charts all include force and time. One without the other is incomplete.

I also think it's a great paper, that I wasn't aware of. The two points in it that I can't help but notice are, the data showing lower peak force over a longer duration was plotted by changing to ammunition that generated intentionally different muzzle energy, the three different Win AA's. The other point is that, in the conclusion, the device is intended to quantify felt differences in the gun, where the ammo is a constant.

My original point was nothing more than it may be atypical to be able to match similar total energy of a 12 ga shell and a magnum rifle cartridge, which I attempted to quantify as muzzle energy.

I'd say our GAF quotients are good all around.

Nice to see that Drew has brought up Mr. Winston, the teller of unfortunate truths. Any and/or all of you are certainly welcome to believe whatever you care to, but Mr. Winston does repeatable, verifiable scientific studies of many of the wonderful Hogwarts Physics contentions that inhabit the shooters' internet.

His so-far unrealized hope is that persons can be self-enlightened if presented with facts. I have wished him the best of luck on several occasions and he has been appreciative of my continuing support. But he hasn't given up even under circumstances that boggle the mind. Even as will certainly occur here. Hopefully he will not subject himself to this place as well.

In many shotshell loads utilizing the "New Fangled" Dense Smokeless Powders the powder charge is no more than 5% of the total weight being launched from the muzzle. With ordinary porting nowhere near all of these powder gases are going to be diverted. As far as recoil reduction in a shotgun goes porting is insignificant & essentially useless. I Ain't a-drilling No Holes in any of my barrels nor letting anyone else do it with my knowledge.

There was a bunch of good stuff, then you kinda lost me at the end. What's the point of luck, when he could have a day.

To the OP's question, there was an article or series of articles published in Handloader Magazine at a much earlier time where the same hulls, 12ga. I believe, were basically loaded until the mouths were shot off or so sorry they would no longer hold shot w/o some added closure devise and both pressure & velocity was measured at each loading. If I recall correctly, there was some degradation of attained velocity, but it wasn't particularly significant even when it was the hulls' last usable loading and pressure was highest on the first reloading as could be reasonably expected.

Pressure & velocity are two dif. animals not related to one another in any mathematical sense as has been noted here and other places multiple times and will only say to not lose sight of that fact.

In my own experience, the yellow 20 ga. hulls get uglier looking [dirty] quicker than the other gauges. Purely a color thing, IMHO, but the hulls are easily enough acquired, so I toss them when they get ugly, tho they would continue to break targets for more reloading's. Mostly the only dif. between once loaded and multiple loadings for skeet ranges is your fingers get dirty along w/the hulls if you don't wear shooting gloves. I don't notice that it affects the numbers of targets broken when the gun is pointed correctly. Dirty hulls breaking as many targets as new ones. Head games are a dif. horse; if you THINK it makes a dif., it probably will and it need not be based on fact.

Phraseology & word choice aside, whot Wonk is saying is the essence of it; don't get too caught up or caught up at all w/meaningless and often wrong minutia as tempting as it may be or as Joe Friday was famous for saying, "Just the facts, Maim."

And please don't read into my remark(s)anything snarky, no intention in that regard exists whatsoever nor trying to refute correct math or that the 96:1 rule is not a fine one for rational limits. It is, but it is also too stout for me were I to shoot many rounds in a day's time. And there is no connection to that and the OP's question either, unless I misread it.

Even though it may be thought of as minutia, I figure truly, what's the big deal. It's only conversation for the fun of it.

If something, referred to as pressure, didn't move a given mass of shot from still and accelerated it to a velocity, what force caused it?

TW,
I'm surprised you drank that water.

Of course pressure and velocity are linked mathematically. Pressure, area which the pressure is applied, and weight are the key physical attributes

Chuck is 100% correct here & both velocity & recoil are dependant on that pressure being applied.
The thing is However neither Velocity nor Recoil can be determined by a comparison of "Peak/Max" chamber pressure.
By using different powders you could load an ounce of shot to 1200 fps @ 10K PSI while you could also load 1� oz to 1300 FPS with only 8K PSI.
Thus there is no direct relation between "Max" pressure & either velocity or recoil, but there definitely is a mathematical relation between pressure & either velocity or recoil.
About all most of us have the means of measuring is the MV. Using that in conjuction with total weight ejected we can then calculate the recoil.

All of the physical components: peak pressure, average pressure, base area (bore) of the ejecta, weight of the ejecta, and time, are all inseparable pieces to the acceleration of the ejecta... and which leads to the opposite reaction, acceleration of the firearm.

At peak pressure, the ejecta will be accelerating at its highest rate (g-force), unless it's constrained from movement. The peak acceleration of the ejecta will coincide with the peak acceleration of the firearm in the opposite direction (not the peak velocity of the firearm). Those recoil charts in Drew's reference tell a lot.