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....

[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

Attachment 116495
Attachment 116496

[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...