Pressure Trace

Stagpanther,

There is a reflected gas pressure wave phenomenon that can occur and that has been known to damage artillery pieces, but rifles are too short for it to occur in. There is a pressure (longitudinal) wave created in the barrel steel when a bullet hits the throat and the chamber starts to expand a little more, but that travels in the steel at around 17 times the speed of sound, so you see its ripples in the pressure trace. There is probably a much slower transverse surface wave associated with that, but I don't think it has much effect on readings. I'm not sure what Jim was referring to.

Yes, the actual pressure is locally much higher at the point of pressure. As I've mentioned in other threads, Texas gunsmith Charlie Sisk has actually blown muzzles off 338's with them. Took him nine or ten shots of a particularly severe one of these loads to do it, but he could do it on demand; totally repeatable. But the photos I saw showed the breech end remaining intact.


Savvy Jack,

Congratulations on getting the unit to work for you. I'll point out you can improve on the graphics resolution. From the 80K at the top of the left side of the graph, I can see you had it in rifle sensitivity mode. Set it for handgun sensitivity and you will see a shorter scale and see the trace more clearly.

Just to give credit where it's due, I'll point out it is actually the hardware in the yellow box that does the measuring. The companion program just downloads the data from the instrument's memory and puts it into files you can store and review or manipulate. Pretty cool system.
 
I couldn't find rifle/handgun but I did find a high res view, is this it?
598a52f3-bdbf-493b-95be-b26f536510d1-original.jpg
 
I put the scope back on today, maybe now I can actually hit that 25 yard target!!!

I had to send off my chronograph to get repaired so it may be a week or so before I can test 6 or 7 more loads plus those I failed to get velocities.



b4f50748-4c51-457f-af05-2a4329cbbb65-original.jpg
 
That plot is what I expected to see. I think the software has changed a little since my older RS232 port version of the instrument was made.

The scope looks snazzy, but for such a short range, I think I'd probably use a laser bore sighter. Green ones visible in daytime are as low as $20 now on Amazon. That one claims to be adjustable for windage and elevation (centering). You could set it up to be right on, though you'd probably need a "top" registration mark painted onto it.

Nice setup, though. Not too many folks have their own version of a universal receiver.
 
It was fun to play with but the scope is just a novelty and to make folks laugh. With the fireing pin thigamjig doohicky pinball thingy removed I can see right down the bore!

I have the red bore sighter that is inserted into the end of the barrel that works much better than the scope. Would rather have the cartridge type laser bore for my rifles but nobody makes one for the 44-40...can't figure that out since it is such a popular cartridge!!!!

More importantly it was a cheep build specifically for the Pressuretrace II equipment. Figured you guys would get a good laugh out of it!!

I really do like the Railguns but no way I can afford to venture that avenue.

Oh, the black pinball knob handle (thanks Stagpanther) is off of a door from a Maule aircraft :-)
 
unclenick is right--you deserve accolades for going above and beyond in trying to further your (and our) understanding of the complex science of ballistics (if that's what this even could be called).
 
Jack,

If you know anyone with a lathe, they could certainly turn a brass adapter for you to let you use a 9 mm or a 38/357 cartridge-type bore sighter.
 
Powder too slow for the bullet weight. The collisions here can ring barrels and Texas gunsmith Charlie Sisk has been able to repeatedly blow muzzles off 338's with them
Click to expand...
.

What does that mean?

F. Guffey
 
I ask because: Sisk was in Iowa Park, Texas and another smith, master machinist etc. was in Ft. Worth, Texas. The Ft. Worth smith/family decide they would venture off into blowing up guns, about the time they succeeded they drew up a different rational for the failures.

F. Guffey
 
I hope this explains why I am using PressuretraceII

Using PressuretraceII allows me to use powders not listed in handloading manuals. Loads for this caliber [44-40] are few and far between. Only three bullets listed of which one is discontinued. It also allows me to compare all powders, including black powder pressures. Even black powders of today can be "weaker" than the black powders of yesteryear. PT-II allows me to load low pressures for my vintage firearms and allows me to get "the most" for my modern strong weapons.

unclenick

Here is a link to some of John Korts writings about early smokeless powders that added to my interests in me wanting to know modern pressures for the 44-40 in psi rather than in CUP using SAAMI's 11,000psi max.

https://www.44winchestercenterfirecartridges.com/single-post/2010/05/20/Early-Powders

Many think the "weak link" into the 44-40's low pressures are attributed to the Winchester 73's weak toggle link when in reality in may actually be the weak steel used in black powder frame pistols. John hits a little on the early Winchester [1895 era] "RED" label smokeless powder offered for the 44WCF.

Early RED label boxes show only the Winchester 73' on the top label with the Winchester 92' being on the side labels indicating early smokeless powder was indeed safe for the 73' contrary to what many think today. It is noted at least on the 1900-1903 boxes that the ammo is for both the 73' and the 92 but "NOT FOR USE IN PISTOLS".

The nomenclature indicated the early smokeless powders were...again...indeed safe for the 73' BUT NOT FOR PISTOLS!!!

Thus it seams that smokeless powder, even those that produce 11,000psi, should never be used in black powder frame revolvers but are safe for all rifles and later stronger steel frame pistols.

To continue...the 1903-1938 Winchester "High Velocity" loads that produced 22,000cup...those Yellow label boxes...on the side label that has the small print, there should be included; "They should never be used in Winchester 73' Rifles". Early 1909 dated boxes show lavender labels "Winchester 92' Special" on the box top but also show "Low Pressure"...indicating truth in the fact that some early smokeless powder actually produced less pressure than the back powder. This causes many modern day shooter's brains to explode with confusion, myths and misconceptions. Even then the side label says "They should never be used in Winchester 73' Rifles".

The High Velocity loads were at some point around 1910 increased in velocity and probably pressures by again changing the label color to Yellow. At some point the Yellow label" High Velocity" loads show for use "Especially for Winchester Rifles 92'" and "NOT FOR USE IN PISTOLS".

It gets really confusing but the Label colors differentiating Smokeless vs Black Powder etc also used later on date codes and file code that explained the date code changes. The date code did not dictate the date the ammo was manufactured but covered the dates to changes made on the labels as well as cartridge component changes such as POWDERS and grains of powder, bullets primers etc used.

If you have not yet checked the link I posted, go do that now for some more explanations. Here is the link again.

https://www.44winchestercenterfirecartridges.com/single-post/2010/05/20/Early-Powders

Also some Colorful cartridge box colors and their meaning.
https://www.44winchestercenterfirecartridges.com/single-post/2018/12/01/Winchesters-Colorful-Cartridge-Boxes


I hope this explains why I am using Pressuretrace II

Thanks to all that helped get me started.
 
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A very interesting thing happened today. I was finishing up my pressure testing today and shot a lot of groups. I decided to shoot some more black powder loads as well. This time, however, I used some original BP brass cases. A variation of Western, REM-UMC and WRA cases. four of the WRA cases used small pistol primers.

First, I shot 15 modern RP cases and 5 Winchester cases. I used 39gr of Swiss FFG in the Winchester cases and 40gr in everything else. 39gr of Swiss FFG gave me an average of 1,221fps from my 20" test barrel producing 8,843 PSI. The 40gr in the RP cases resulted in 1,257fps and 8,648 psi. Here is the kicker.....

I used 40gr of Swiss FFG in 16 original semi-balloon head cases of which four were small pistol primers. Same powder, same bullets, except for the four pistol primer cases...basically the same primers.

1,373fps @ 14,100psi!!!!!! HMMMmmmmmmm!!!!!!


On another note, to include the BP tests, I shot 42 pressure testing groups of at least 10 shots per group over the past few months.
Included are all of Lyman's 49th, page 299 and 300, MAX loads for both Group I and Group II rifles using Unique, IMR4227 and 2400 with the published bullets, primers, case lengths and AOL's.

All of my Group I loads ranged between 6,594psi to 9,389psi
My "Control", Buffalo Bore's 44-40 "Heavy" was set to 11,300psi.
All of my Group II loads came in between 11,363psi to 17,837 psi

What I failed to do was shoot all loads at the same out side air temps. The "Control" was shot in about 55 deg, some loads shot around 35 deg and the rest also around 55deg. This does change things a little but not too awful much. Some could increase as much as 1,500psi and those shot in 55deg could increase in 90deg weather.

However, out of all of the loads I have ever come up with on my own, only TWO were higher than the Lyman's MAX pressure results of 17,830psi. Those two were 19,500psi and 19,628psi.

Only one Reloder 7 load came in over 13,500psi and it was a 240gr LRNFL bullet and it achieved 1,446fps.
Other 240gr LRNFP bullets with a lighter load stayed below 11,000psi

Most case capacity Reloder 7 loads stayed between 10,000psi and 13,000psi. Even a caseload of Trailboss surpassed SAAMI max out to 15,182psi

The Pressuretrace II system was well worth the $$$ for a little piece of mind as well as closing the mouths of a few Mr, been handloading for 55 years, Know-It-Alls.
 
Jack,

Interesting about the cases and BP velocities in particular. Have you measured the actual case volume? How much water weight each case will hold when they are the same length?


I ask because: Sisk was in Iowa Park, Texas and another smith, master machinist etc. was in Ft. Worth, Texas. The Ft. Worth smith/family decide they would venture off into blowing up guns, about the time they succeeded they drew up a different rational for the failures.

F. Guffey
Click to expand...

I thought I had answered this earlier, but I must have started to compose the post and never finished. Charlie Sisk is a member at The 24hr Campfire forum, which is where I saw his photos originally. I'm glad I looked again for this reply, because there is now (as of 2015) some additional data from Denton Bramwell suggesting the size of the pressure jump may be an instrumentation artifact, but doesn't explain why it appears only with the light-bullet, slow-powder combinations and goes away when you either go to faster powder or a heavier bullet. The barrels blew off OK, but Sisk, who mentioned it in a June 2004 Handloader article, says he was never satisfied that they found a clear answer to the problem. Only that using very slow powder in 308 Win, 338 Win Mag, or 374 H&H let him routinely blow the ends of barrels, shortening them to about 21.7" regardless of the barrel contour or its length beyond that 21.7" point.

Denton Bramwell suggests the energy in the powder is inadequate to explain the blow-offs, but I know that's incorrect. Muzzleloaders have experienced barrel bulging by what is called "short seating" for decades, but Bramwell is correct that the damage splits them lengthwise when it happens in the range of three to six inches in front of the normal location of the end of the powder column.

So, the mystery deepens. Here is the 24 Hr. Campfire thread with more recent theories from 2015. Sisk also comments in it.
 
Jack,

Interesting about the cases and BP velocities in particular. Have you measured the actual case volume? How much water weight each case will hold when they are the same length?
Click to expand...

Typically my RP brass yields about 41gr/v H20, Starline 42gr/v H20 and these Semi-Balloon head cases 44gr/v H20
 
Interesting read there Jack and I can certainly understand why you like this gear. There is a gent at the range who shoots the big bores a lot and he pays every bit as much attention to his reloading as the long range guys do. He is always tweaking his loads. Next time I see him I will mention this thread
 
My Pressuretrace stopped working today when I hooked it up. The box light remains on "Data Captured" rather than "Synchronized". The popup window created says it is not properly configured....and to contact the supplier. Sent a message off to Jim but thought I might try here first if it can be a quick fix!
 
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