Experience with Pressure Trace II?

[rickster]

Anyone have experience with Pressure Trace II? How well does it work? Which of the product options would you recommend?..........

http://www.shootingsoftware.com/pressure.htm

[redneckdan]

I've been looking at them for a while...guess its just the engineer in me. Kind of an expensive toy though....:groner:

[Savvy Jack]

I'd like one myself

[MaryB]

Yikes expensive stuff... would be fun though. Settle the 5.56 vs 223 arguments.

[Doc Highwall]

I have one with the CED M2 chronograph and I really like it.

[Savvy Jack]

I have one with the CED M2 chronograph and I really like it.

Doc, did you get the $500 package or the whole deal? I really only want to test pressures for one cartridge....Do I just need the basics?

[williamwaco]

It appears to me that it doesn't work with handguns or rifles without direct access to the barrel at the case mouth ?

[Savvy Jack]

That what it looks like to me. a 44-40 Thomson Contender would probably be a nice test platform. The Marlin would work fine.

Best on a revolver would be the cylinder used but then rotation would not work. Maybe a Smith & Wesson Model 3, or Schofield with a top break action.

My plan would be the Rifle. Pressures for the same load would be lower in the revolver do to the cylinder gap and space between the cylinder/bullet and forcing cone.

[shooter93]

Savvy Jack....The 454 Casull people, Speer laboratories and Mic McPherson have all found times when the pressure of the exact same load was much higher in a Revolver than in a closed breech gun. Most of the tests were with jacketed bullets but it is an interesting phenomenon for one to remember. Goes against "common knowledge" but it happens.

[Savvy Jack]

lol, I am not surprised. I was just thinking about when the bullet hits the forcing cone wondering if that would spike the pressure to an even greater pressure than a rifle.

[Doc Highwall]

I got the whole package.

[OuchHot!]

I do not have one of these but as a kid in engineering school "built" one. I used a '03 action and barrel. Since I accurately knew (by meticulous measurement) the dimensions at various locations and the modulus, I could pretty accurately predict strain with respect to temperature both at the chamber and down the barrel. College professors, being what the are, I also had to come up with absolute calibration. This I did corking both ends and hydrostatically loading the system to several pressures and getting a calibration curve and verifying that my strain gages were in their linear range. The short story is that somewhere or other all of these systems will require a reference to guesstimate pressure. You want to use the simplest structure possible where the strain gage is located. A TC or reference bolt action with a bull barrel is probably best. The modulus between steels isn't too much of a variable but thickness at the strain gage needs knowing or you must reference to a factory load and assume its peak pressure. Ultimately, there will be a fudge factor, relative measurements can be very good but don't rely on perfect resolution of peak pressures.

[Savvy Jack]

I thought I saw somewhere that octagon barrels are hard to gauge!



I do not have one of these but as a kid in engineering school "built" one. I used a '03 action and barrel. Since I accurately knew (by meticulous measurement) the dimensions at various locations and the modulus, I could pretty accurately predict strain with respect to temperature both at the chamber and down the barrel. College professors, being what the are, I also had to come up with absolute calibration. This I did corking both ends and hydrostatically loading the system to several pressures and getting a calibration curve and verifying that my strain gages were in their linear range. The short story is that somewhere or other all of these systems will require a reference to guesstimate pressure. You want to use the simplest structure possible where the strain gage is located. A TC or reference bolt action with a bull barrel is probably best. The modulus between steels isn't too much of a variable but thickness at the strain gage needs knowing or you must reference to a factory load and assume its peak pressure. Ultimately, there will be a fudge factor, relative measurements can be very good but don't rely on perfect resolution of peak pressures.

[Savvy Jack]

I'd like to test this one

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[OuchHot!]

I would have to think on it some more but I think that the deformation of an octagon barrel would be a reflection of the hoop stress computed on the base circle and the corners would sorta be along for the ride. Obviously the '03 was cylindrical so that complication didn't come in to play. I now have a Siamese mauser in 45-70 and I sure would like to compare the effects of its long gentle throat to my Miroku (no throat to speak of) copy of the 1886. I would like one of these rigs pressure reading rigs. The specification of pressure by factories is a bit of a mystery to me. "Peak" pressure is dependent on how fast you can take data and that is rig/program dependent. Maybe they report and averaged pressure based on area under a curve over so many milliseconds. There are lots of ins and outs to consider.

[Savvy Jack]

I have been reading some articles online and it seems you have to disgrace the barrel bluing in order to get a good reading. Probably just cheaper to find someone to test a few loads for me :-)

[Savvy Jack]

So are revolver pressures greater than rifle pressures?

[OuchHot!]

I do not know any reason why they might be. The early stage of the ignition sequence might show a peak if you meticulously fit your bullet to the cylinder throat Vs. a sloppy rifle chamber. I can feel extraction differences with a well fitted bullet in my .45 Colt as compared to the same bullet sized down a might. The thing that concerns isn't that the revolver might show higher pressure but that it might be less tolerant of higher pressures than the usual rifle chamber. The breaching of the rifle barrel pretty much means extra meat in that area.

[Larry Gibson]

Yikes expensive stuff... would be fun though. Settle the 5.56 vs 223 arguments.

Surprisingly you'd think it would settle the .308W vs 7.62 NATO also.........

I've been posting the pressure of both "controversies" for several years hear and other other forums. Some believe the results and accept it. Others prefer to still believe in old "guestimates", rumors and barrack type BS statements. Many still believe most internet sites" which supposedly "prove" the difference". Most of those are based on a misunderstanding of C.U.P. pressure figures and those taken by modern transducers and strain gauges. The other misunderstanding is the mistaken belief all factory and arsenal loaded cartridges are actually loaded to the specified MAP (Maximum Average Pressure). Most all are not close to the MAP for the cartridge and some are a lot lower. The silliest of all is the "expert" opinions is based on a supposed difference in the cartridges pressure (MAP) because the headspace dimensions are different.

I still plug away correcting the mistaken statements by posting actual pressures measured with my Oehler M43 PBL system. As I said; some believe facts other still believe the myths, the witchcraft and the BS.

Larry Gibson

[mdi]

Yikes expensive stuff... would be fun though. Settle the 5.56 vs 223 arguments.
Now, you know you can't settle arguements/wives tales with facts...:veryconfu

[Larry Gibson]

OuchHot

I don't know about the Pressure Trace system but the Oehler provide for input of the calibration data of the strain gauge Same as the transducers have "calibration data" that is input) and the measurement of the thickness of the barrel at the center of the strain gauge. The strain gauges should ideally be placed of the center of the combustion area of the cartridge. The M43 System also runs a "check" to ensure the gauge is functioning properly prior to every test. The gauge has to function properly or the test is aborted.

I also use a specific lot of ammunition that I've received the tested psi of as "reference ammunition" and then compute the "correction factor" for the psi recorded in that test barrels. The use of "reference ammunition is the industry standard way of doing "calibration". Additionally I have one large lot of ammunition for one rifle that is initially used at the beginning of every set up of my equipment to verify the system is functioning correctly.

Doc Highwall and I are beginning a process of comparison between the data produced by the Pressure Trace System and the Oehler M43 with the same loads.

Larry Gibson

[Savvy Jack]

Larry, thanks for this information. The more I look the more the testing is beyond my finances other than maybe the Pressure Trace system. My problems are two fold. First I need a round barreled chamber. I have all octagon barrels or revolvers. Second problem is getting known pressure ammo for the 44-40....I don't know of any and I am not getting any feedback from manufactures on ANYTHING. A few powder companies basically won't touch it. You can find my topics over on the Marlin "Team 44-40" forum. http://www.marlinowners.com/forum/team-44-40/ . I have some chronograph and clear gel results on High Velocity Hollow points and original High Velocity replications with Winchester bullets.

Does anyone out there still use the Copper Crusher method?

Sorry, I forgot links to some videos too.

https://www.youtube.com/watch?v=SyicsZDSUV0

And a few photos of todays test.

Once again my lack of experience cause mixed results but good news. I loaded up the 6 with rifle in hand and shot at 100 yards. The first two shots hit the very right edge of the gel block just a few inches low right of POA. Then the next two hit the table top 10 inches low right from POA. I did not expect my scope to be zeroed in for this load but wow. One hit the rear post of my chronograph but was bent back out. The next one went into outer space I guess of which all where not recovered!!

1903 - Introduction of the W.H.V. (Winchester High Velocity) cartridge

We first see these new improved performance cartridges in Winchester’s Catalog #70 dated March, 1903. Cartridges were head stamped .44 W.C.F. W.H.V. ’M92. Velocity with a 200 gr. metal patched bullet was catalogued at 1,500 f.p.s. in a 24” barrel. Instructions in Winchester’s catalogue and on the cartridge boxes indicated they were not for use in ’73 Winchesters or handguns. Velocity was increased to 1,570 f.p.s. in 1910.

U.M.C. brought out their .44-40 high velocity cartridge shortly after Winchester did. Cartridges were head stamped U.M.C. .44-40 H.V. to distinguish them from the U.M.C. .44-40 head stamp used on the standard cartridge. Catalogued velocity from the start was 1,570 f.p.s. with a 200 gr. bullet. PETERS used the .44-40 H.P. designation. ~ w40wcf

I think somewhere John said that the original ballistics generated 22,000 CUP and that the Lyman reloading manual #49 shows a 200gr Speer JHP 20.0/2400/1,638/19,000 CUP from a rifle.

Thus my two pressure test loads would be

1. Speer .430 210gr Gold Dot Hollow Point 20.0/2400/est. 1,583/est. 22,000 psi
2. Winchester .426 200gr JSP 20.0/2400/est. 1,600/est.19,000 psi


Here is what I do have,

Rifle - Marlin 1894CB with scope

2 shot avg. 1,386fps @ 100 yards

I loaded up two more but this time used Winchester brass and WLP's

Revolver @ 10 ft.
(44 MAGNUM FRAME)
1,138fps
full penetration
PLUS
1 gal of water
PLUS
1/2" penetration into pine 2x4 plank
THEN
bounced back into the water jug OF WHICH the plug from back of the jug, created by the bullet metplate, stayed in the 2x4

No deformation!!!!!


Center shot is from revolver @ ten feet.
Foreground is one of the 100 yard shots
The second 100 yard shot is below the ruler.

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[OuchHot!]

Larry, your Oehler system is surely light years ahead of the contraption I put together in the 1980. The computer that I used had a hard time archiving 2000 data pts in a second which pretty much tells you that my peak pressures sure weren't! My strain gages were pretty big (recollection is poor but maybe 4mm) and I wound up using two in a 45 degree vee to back calculate hoop stress. The end of the day it was hoop jumping for a student not a real world pressure testing system. The modern era I-phone is likely more powerful than the HP mini-mainframe that I used. I read your post avidly, thanks.

[Michael J. Spangler]

Bringing this one back from the dead.

I’m thinking of making the purchase this week and was hoping there was some more info on this. Thanks!