How to measure chamber pressure?

[harry_x1]

Hi All,

I understand there are multiple ways to check for signs of pressure after firing a round, but I was wondering if there is some kind of a tool which can help measure actual pressure inside the chamber when firing?

Any feedback, inputs will be helpful

thanks
harjeet

 

[WSnyder]

No idea if they are still on the market but there were multiple strain gauge setups you could buy. You glued a thin strain gauge over the chamber on the barrel.

Strain, bastid phone auto correct!

 

[thebeav]

'Strain'
Of course, gun and ammo manufacturers have a threaded port into the chamber, fitted with a pressure transducer which feeds an oscilloscope.

 

[243winxb]

industrial systems from Oehler. About $15,000 for 1 gauge.
https://oehler-research.com/system-83-ballistic-instrumentation/

​

 

[std7mag]

RSI Pressure Trace.

Rifle Barrel Chamber Pressure Testing Hardware & Software | Pressure Trace

Measure ACTUAL rifle chamber pressure for each shot, barrel harmonics, rise time, time to muzzle exit and OBT barrel timing.

www.shootingsoftware.com

 

[choprzrul]

RSI Pressure Trace.

Rifle Barrel Chamber Pressure Testing Hardware & Software | Pressure Trace

Measure ACTUAL rifle chamber pressure for each shot, barrel harmonics, rise time, time to muzzle exit and OBT barrel timing.

www.shootingsoftware.com

Does anyone have first hand experience using one of these?

 

[Walt Krafft]

I have one and use it. It works ok to see differences shot to shot. The problem with all pressure systems is calibration. Without a known pressure standard to calibrate your system, all you have is a number. By itself, that number is not much good.

 

[gunsandgunsmithing]

What Walt said. It'll get you in the ballpark if it's a standard chamber that you can calibrate to factory ammo, but it's not intended to give absolute pressure values.

 

[mikecr]

I don't think there is a practical way to measure it, nor a practical reason for the endeavor.
Your system is stronger than brass, so your brass will give out first (provided you work up smartly).
Does it matter what actual pressure is?
Only for the science in it.

 

[Florida Wally]

Does anyone have first hand experience using one of these?

Here is a video.

 

[mikecr]

I agree with Walt #7 post.
The RSI pressure trace/strain gauge measurements are interesting,, but of little actual use.
Given all the time it takes to manage a good load, you won't be fiddling with pressure measurement much.
A RADAR unit is money-time better spent.

 

[ronemus]

General practice seems to be to use commercial ammunition to"calibrate" the Pressure Trace, making the assumption that it is loaded to max pressure; however, pressure strongly depends on the barrel and to some degree on the chambering. It is most useful for reassuring yourself that your loads aren't excessive, but it will not provide absolute pressures. If you use a load with a pressure measurement such as is provided in some reloading manuals, and it produces the same velocity in your barrel, you can use that as a reference when heading into unknown territory.

 

[59FLH]

After watching the video I wonder if his QL data would have been of better value for calibration if he used actual measured velocity vs estimated for his modeling

QL states +/- 10% for powder lot variations

 

[neckturner]

RSI Pressure Trace.

Rifle Barrel Chamber Pressure Testing Hardware & Software | Pressure Trace

Measure ACTUAL rifle chamber pressure for each shot, barrel harmonics, rise time, time to muzzle exit and OBT barrel timing.

www.shootingsoftware.com

Looks like RSI Pressure Trace is out of business.

Anyone know of an alternative?

 

[ronemus]

There is some support here.

There is no obvious support those of us who have Shooting Lab.

 

[Walt Krafft]

I could be talked out of mine. Send me a pm.

 

[243Lapua]

Get in contact with Bill Wiseman for this kind of things.

 

[neckturner]

There is some support here.

There is no obvious support those of us who have Shooting Lab.

Thanks, I had that link earlier and lost it.

 

[XTR]

I have an RSI unit. I like it a lot.
The problem for the interwebz measure everything crowd is you can’t effectively calibrate it; however, if you understand testing methods then it, combined with a good chrono can give you way more useful information than trying to read the tea leaves of primer deformation and sticky bolts or playing with the numbers to make your loading prediction program match your observed data.

if they are really out of business I wish I’d bought another pack or two of strain gages. People I know who have made their own say they are well worth the price compared to making them.

 

[dcali]

I would argue that for 99% of us, there's not much to be gained from measuring pressure other than to satisfy curiosity (which is not nothing). Brass is the failure point, and it's not really that difficult to figure out without measuring pressure.

Properly calibrated pressure measurements would be useful in certain gun design applications, but how many of us are doing that?