Reading Pressure

[MagnumManiac]

Have you, by chance, compared your pressure results against Quick Load? I am just wondering what you see with piezoelectric sensors in comparison to the QL results. Video would have been more meaningful with this type of information.

Initially, I ran QL side by side with the Pressure Trace, with lots and lots of tweaking burn rates and other factors I could get QL sort of close, but never matching actual results. Many results showed max pressure was no where close to QL predictions.
The parameters had to be so manipulated that in the end I gave up on QL and sold it.
I have to add that I do not use my Pressure Trace testing with a fudge factor, nor do I use a factory round as calibration, because factory ammo is rarely running at max pressure.
Mostly, I look for a flattened plateau in pressure, this is where uniform results are found, and primer testing often alters this significantly and can turn a crapshoot into a good thing.

Cheers.

 

[Weaver93]

Initially, I ran QL side by side with the Pressure Trace, with lots and lots of tweaking burn rates and other factors I could get QL sort of close, but never matching actual results. Many results showed max pressure was no where close to QL predictions.
The parameters had to be so manipulated that in the end I gave up on QL and sold it.
I have to add that I do not use my Pressure Trace testing with a fudge factor, nor do I use a factory round as calibration, because factory ammo is rarely running at max pressure.
Mostly, I look for a flattened plateau in pressure, this is where uniform results are found, and primer testing often alters this significantly and can turn a crapshoot into a good thing.

Cheers.

Very interesting and thanks for the reply. If you ever do a video of your process, post it. If you have, point me in the direction. It would be educational to see it done!

Thanks again!

 

[cape cove]

@MagnumManiac
One thing I have always wondered about QL is they state to add 7200 psi to the already 3626 psi start pressure if touching the lands for a total of 10826 psi vs a load that is away from the lands, say .050. What would be your take on this. How much pressure would you add to touch vs away from the lands. TKS.

 

[MagnumManiac]

@MagnumManiac
One thing I have always wondered about QL is they state to add 7200 psi to the already 3626 psi start pressure if touching the lands for a total of 10826 psi vs a load that is away from the lands, say .050. What would be your take on this. How much pressure would you add to touch vs away from the lands. TKS.

Yep, I would agree with this as I found jammed by .010"-.015" to raise start pressure by as much as 10,000psi. Even a heavy crimp would raise pressure by 8,000psi on 65,000psi max loads. Something I always avoided adding without working up again. My 416 Rigby jumped more than 100fps by simply adding a .050" deep roll crimp…

Cheers.

 

[MagnumManiac]

Very interesting and thanks for the reply. If you ever do a video of your process, post it. If you have, point me in the direction. It would be educational to see it done!

Thanks again!

I have tried many times to post video here unsuccessfully, unsure why it fails, but I have also deleted most of my YouTube stuff since selling my business. I am no longer testing anything actually.

Cheers.

 

[FireFlyFishing]

It's published now. lol

Fair enough!

 

[asd9055]

Initially, I ran QL side by side with the Pressure Trace, with lots and lots of tweaking burn rates and other factors I could get QL sort of close, but never matching actual results. Many results showed max pressure was no where close to QL predictions.
The parameters had to be so manipulated that in the end I gave up on QL and sold it.
I have to add that I do not use my Pressure Trace testing with a fudge factor, nor do I use a factory round as calibration, because factory ammo is rarely running at max pressure.
Mostly, I look for a flattened plateau in pressure, this is where uniform results are found, and primer testing often alters this significantly and can turn a crapshoot into a good thing.

Cheers.

Tony, was QL over predicting or under predicting the pressure vs the pressure trace?

 

[MagnumManiac]

What QL predicted was way under max in MY rifles. One caveat that has to be addressed is that only a few of my rifles could actually be tested at 1/3 the length of the chamber. This is determined by where the optimum width of the Knox form is and not on a tapered section. Many put them there on the taper, but this is not ideal. The length of the front action ring also makes it difficult.

Cheers.

 

[asd9055]

What QL predicted was way under max in MY rifles. One caveat that has to be addressed is that only a few of my rifles could actually be tested at 1/3 the length of the chamber. This is determined by where the optimum width of the Knox form is and not on a tapered section. Many put them there on the taper, but this not ideal. The length of the front action ring also makes it difficult.

Cheers.

Thank you.

 

[4th_point]

Have you, by chance, compared your pressure results against Quick Load? I am just wondering what you see with piezoelectric sensors in comparison to the QL results. Video would have been more meaningful with this type of information.

FYI - Pressure Trace uses strain gauges, which are not piezoelectric sensors. Strain gauges are glued to the exterior of the barrel and measure strain (tension, compression, or no change) in that specific location. A strain gauge does not directly measure chamber pressure, but can be used to estimate it. To directly measure pressure, you need a chamber pressure transducer/sensor.

 

[cape cove]

What QL predicted was way under max in MY rifles.

That seems to be what QL is doing concerning my 6mm ppc usa Sako. Giving lower pressure readings than what I believe they actually are. although the load does seem rather light.

 

[Weaver93]

FYI - Pressure Trace uses strain gauges, which are not piezoelectric sensors. Strain gauges are glued to the exterior of the barrel and measure strain (tension, compression, or no change) in that specific location. A strain gauge does not directly measure chamber pressure, but can be used to estimate it. To directly measure pressure, you need a chamber pressure transducer/sensor.

Yeah, I used the terminology (piezoelectric sensors) that @MagnumManiac used in his reply for the sake of clarity. I have no knowledge of pressure trace. Used plenty strain gauges on crane booms though.

Most people don't want to drill holes in their chambers for a transducer. Kinda detrimental to future use.

 

[4th_point]

Yeah, I used the terminology (piezoelectric sensors) that @MagnumManiac used in his reply for the sake of clarity. I have no knowledge of pressure trace. Used plenty strain gauges on crane booms though.

Most people don't want to drill holes in their chambers for a transducer. Kinda detrimental to future use.

I get what you are saying.

So you understand that using strain gauges has limitations for this application, and that's why labs use chamber transducers. But some people don't.

 

[Weaver93]

I get what you are saying.

So you understand that using strain gauges has limitations for this application, and that's why labs use chamber transducers. But some people don't.

Yep, chamber transducers are necessary to measure exact pressures of loads. Not very practical outside the manufacturing application though. If I'm not mistaken they use an elastic material as well as an electrical component that converts the deformation of the elastic material into an electrical signal.